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From flat pulleys to toothed pulleys


In machines where a positive drive is essential and no slip between belt and pulleys can be accepted, a toothed belt and pulley is used. Toothed belts are mainly used for timing mechanisms, where quiet, positive (no slip) drive is required. The figure below shows a toothed belt and toothed pulleys used to drive a camshaft in a motor car engine.




Toothed belt and toothed pulleys
















The gear wheel


The gear wheel is a basic mechanism. Its purpose is to transmit rotary motion and force. A gear is a wheel with accurately machined teeth round its edge. A shaft passes through its center and the gear may be geared to the shaft. Gears are used in groups of two or more. A group of gears is called a gear train. The gears in a train are arranged so that their teeth closely interlock or mesh. The teeth on meshing gears are the same size so that they are of equal strength. Also, the spacing of the teeth is the same on each gear. An example of a gear train is shown below.



Single geargear train











Rotation direction

When two spur gears of different sizes mesh together, the larger gear is called a wheel, and the smaller gear is called a pinion. In a simple gear train of two spur gears, the input motion and force are applied to the driver gear. The output motion and force are transmitted by the driven gear. The driver gear rotates the driven gear without slipping.
The wheel or the pinion can be the driver gear. It depends on the exact function the designer wishes the mechanism to fulfill. When two spur gears are meshed the gears rotate in opposite directions, as shown in the figure below.




Wheel and pinion

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Introduction to rotary motion


Introduction to flat pulleys:

Rotary motion is the most common type of motion for a shaft or an axle. One way in which an engineer uses rotary motion is by transmitting it from one shaft to another when the shafts are parallel. This can be done by using pulleys and belts. A pulley is a wheel which may or may not have a grooved rim.
The figure below shows a stacked vee pulleys and vee belts often used in car engines.






The main function of pulleys and belt systems are to transmit motion and torque from an engine to a machine. Various types of pulleys and belts are used on different machines. Machines used in the home, such as sewing machines, washing machines, spin dryers and vacuum cleaners. The picture below shows a flat belt and flat pulley used to transmit motion from an old heat engine.

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The Gearbox (Transmission)

Types of gearing:

Various types of gearing are used on a motor vehicle. The gearboxes employ one or more of the following:

1- Spur, teeth parallel to axis, used on sliding mesh.

2- Helical, teeth inclined to axis to form helix.

3- Double helical, two sets of opposing helical teeth.

4- Epicyclic or planetary, spur or helical gears rotating about centers which are not stationary.

Gear ratio (single gear train):

The gear ratio, or velocity ratio, between a pair of gear wheels is in inverse ratio to the number of teeth on each. Thus:

N_B/N_A = D_A/D_B= n_A/n_B

N_B = N_A (n_A/n_B)

Where:

N_A= rev per min of gear A, n_A = number of teeth on A

N_B = rev per min of gear B, n_B = number of teeth on B

D_A = Diameter of gear A
D_B = Diameter of gear B

Power, Speed and Torque:

The power transmitted by a shaft is directly proportional to the speed of revolution and the torque acting on it

Power [kW] = 2 p N T / (60 x 1000) [N.m/s]

Then

T_A N_A = T_B N_B

For a given power, therefore, the torque is inversely proportional to the speed of revolution and if the re min is reduced the torque will be increased in the same ratio (assuming 100% gear efficiency).

T_B/T_A = n_B/n_A

Where:

T_A = torque transmitted by A

T_B = torque transmitted by B

Velocity or gear ratio (i_g) = number of teeth on driven gear/number of teeth on driver gear.

T_B = T_A (n_B/n_A) = T_A/ i_g

Compound gear train:

If the number of teeth on each wheel is known, the relationship between the speed of wheels A and D can be determined as follows

For wheels A and B: N_B/N_A = n_A/n_B, i.e. N_B= N_A (n_A/n_B)

Wheel B and C are fixed on the same shaft, so N_C=N_B

For wheels C and D: N_D/N_C = n_C/n_D, i.e. N_D = N_C (n_C/n_D)

Substituting N_C = N_B = N_A (n_A/n_B) from above, we get

N_D = N_A (n_A/n_B) (n_C/n_D)

Or N_D/N_A =

By inspection of the layout of the figure, it will be observed that wheels A and C are driver gears while B and D are driven gears. Hence, from the above equation

Velocity or gear ratio (i_g) = product of teeth on driven gears/ product of teeth on driver gears

N_D = N_A (n_A/n_B) (n_C/n_D) = N_A (n_A n_C / n_B n_D) = N_A/i_g

Example:

A double reduction set of gearing is as shown in the above figure. Wheel A is the driver gear, wheels B and C fixed to the same shaft and wheel D is the final gear in the train. The number of teeth on each wheel is A=20, B=50, C=40, D=30 teeth.

a- Determine the velocity ratio of the gearing system.

b- Calculate the speed of rotation of wheel D when wheel A rotates at 1800 rev/min.

c- Calculate the torque of wheel D when the torque of A is 100 N.m and the efficiency of the gear train is 90%.

a- Velocity ratio = product of teeth of driven gears/ product of teeth on driver gears

i.e. velocity ratio (i_g) = (n_D n_B / n_C n_A) = (30 x 50) / (20 x 40) = 1.875

b- N_D = N_A / i_g = 1800 / 1.875 = 960 rev/min

c- T_D = T_A i_g h_g = 100 x 1.875 x 0.9 = 168.75 N.m

Types of Drives and gearboxes

There are many types of the car drives, usually classified accordance with number of driving axles (4x2, 4x4, 4WD, AWD) and each type has a different gearing arrangement. Also, gearbox (transmission) has different types (sliding-mesh, constant-mesh, synchro-mesh) some of them are old-fashion and had been replaced, and some are in use in modern cars.

SLIDING-MESH GEARBOX:

The sliding gearbox was popular on cars up to about 1930, but it is rarely used. The basic layout of a 4-speed and reverse gearbox is shown in the figure. The various spur-type gears are mounted on three shafts.

o Primary shaft (alternative names – clutch or first motion shaft)

o Layshaft (countershaft)

o Mainshaft (third motion shaft).

Primary shaft

This shaft transmits the drive from the clutch to the gearbox. At the end, the shaft is supported by a spigot bearing positioned close to the splines on to which the clutch driven plate is connected. The main load on this shaft is taken by a bearing; normally a sealed radial ball type, positioned close to an input gear called a constant mesh pinion. The gear is so named because it is always in mesh with a larger gear, a c constant mesh wheel, that I part of the layshaft gear cluster. Note that a small driving gear is called a pinion and a large gear a wheel.

Lay shaft
This shaft, which is normally fixed to the gearbox casing, supports the various-sized driving pinions of the layshaft gear cluster.

Main shaft
This splined output shaft carries spur gearwheels that slide along the shaft to engage with the appropriate lay shaft gears. At the ‘front’ end, the main shaft is supported by a spigot bearing situated in the centre of the constant mesh pinion. A heavy duty radial ball bearing is fitted at the other end to take the force of the gears as the attempt to move apart.

Gear positions

Neutral

All main shaft gearwheels are positioned so that they do not touch the layshaft gears. A drive is taken to the layshaft, but the mainshaft will not be turned in neutral position.

First gear

The firs-speed gearwheel A on the mainshaft is lid backwards to engage with pinion B on the layshaft; all other gears are positioned in neutral. In this gear, the reduction in speed that occurs as the drive passes through the constant-mesh gears, E and F, is reduced further by the firs-speed gears, A and B.

The gear ratio (also called the movement ratio or velocity ratio) is given by

Ratio = (Driven/driver) x (driven/driver)

I_g1 = (F/E) x (A/B)

N_{output 1} = N_input / i_g1

T_{output 1} = T_input x i_g1 x h_g1

Second gear

The second-speed gearwheel C is slid forward to engage with the layshaft gear D; all the other gear are set in the non-driving position.

I_g2 = (F/E) x (C/D)

Third gear

In this gear position, gearwheel G is slid in to mesh with gear H.

I_g3 = (F/E) x (H/G)

Top gear

In this layout, fourth gear is a direct drive; namely a gear that gives a ratio 1:1. It is obtained by sliding gear G to engage its dog teeth with the corresponding teeth formed on the end of the constant mesh pinion E. Engagement of the dog clutch locks the primary to the main shaft and this gives a ‘straight-through’ drive.

Reverse gear

Sliding a reverse gear between any two gears on the layshaft and main shaft is the method used to change the direction of rotation of the output shaft.

The simplest arrangement uses a single reverse gear, which is mounted on a short shaft. This shaft is positioned so that the reverse can slide and mesh with the two first-speed gears as shown in the figure. The gear ratio is

i_gr = (Driven/Driver) x (Driven/Driver) x (Driven/Driver)

= (F/E) x (J/B) x (A/J)

= (F/E) x (A/B)

This is the same ratio as for first gear, and irrespectively of the size of gear J, it will be seen that the ratio always remains the same. For this reason it is called an idler – it changes the direction, but does not alter the ratio.

With the idler arrangement, some drivers persistently slip the clutch to maintain a low reversing speed. Excessive clutch wear resulting from this practice is minimized when the reverse ratio is set lower than first gear. This achieved by using a reverse gear arrangement as shown in the figure. Instead of single idler, the compound reverse gear has two gear pinions joined together. The reverse shaft is positioned so that the reverse pinions are able to mesh simultaneously with the appropriate layshaft and mainshaft gears.

Gear Changing

When one gear is moved to engage with another gear noise will result if the peripheral (outside) speeds are not the same to avoid this, the driver of the vehicle having a sliding-mesh gearbox performs an operation called double declutching.

Select mechanism

A fork of the type shown in figure is used to slide a gearwheel along the main shaft in order to select the appropriate gear. It is mounted on its own rod and links the driver’s gear stick to the sliding gearbox. Every gearbox must be fitted with the following:

1- Selector detent-

Holds the gears and selectors in position and so prevent gear engagement or disengagement due to vibration. The figure shows a typical arrangement suitable for a layout having the selector fork locked to the rod.

2-Interlock mechanism-

Prevents two gears engaging simultaneously; if this occurs the gearbox will lock up and shaft rotation will be impossible. Although the interlock device takes a number of different forms, the arrangement shown in the figure is one of the most common.

Power take-off arrangement

In addition to the mechanism use for driving a vehicle along a road, a power supply is often required for operating external items of auxiliary equipment.

A light truck having a tipping mechanism is one example, but the most varied application of power take-off units is associated with specialized off-road vehicles.
The figure shows a typical power take-off arrangement that is driven from the gearbox layshaft.

Disadvantages of the sliding mesh

Although the mechanical efficiency of the sliding mesh gearbox was high, it suffered from two great disadvantages:

1- Gear noise due to the type of gear.

2- The difficulty of obtaining a smooth, quit and quick change of gear without the great skill and judgment.

CONSTANT-MESH GEARBOX

The main feature is the use of the stronger helical of double helical gears which lead to quieter operation. In this design, the mainshaft pinions revolves freely on bushes or needle-roller bearings and are all in constant engagement with the corresponding layshaft wheels. The gear operation is obtained by locking the respective gear to the main shaft by means of a dog clutch. The layout of the box is shown in the figure.

With this arrangement the quieter-running helical gears can be employed, and during gear changing the noise and wear are reduced by the simultaneous engagement of all the dogs instead of only a pair of gear teeth as on the sliding-mesh gearbox.

With single helical pinions (double helical is economically impractical), the driving loads on the teeth cause an axial thrust which must be resisted by thrust washers, or shoulders, on the mainshaft.

CONSTANT-LOAD SYNCHRO-MESH

The figure shows unite main details of. Fundamentally the box is laid out in same manner as a constant-mesh, with the exception that a cone clutch is fitted between the dog and gear members. The initial movement of the selector a sleeve carries the hub towards the gear and allows the cones adjusts the speed of the gearwheel to suit the hub and mainshaft. Extra pressure on the lever will allow the sleeve to override the spring-loaded balls, and positively engage with the dogs on the gear.

BAULK RING SYNCHRO-MESH

This system is designed to overcome the main disadvantage of the earlier design- noise or crashing of the gears due to a quick change, by adding baulking ring to do the job as shown in the figure.

ADDISIONAL GEAR RATIOS

Commercial vehicles having a relatively low power/weight ratio, and operating under unladen to fully loaded conditions, require additional gears for efficient operation.

ALTERNATIVE RATIO GEARBOX:

A- One arrangement is to provide two pairs of alternative-ratio constant mesh gears between the clutch shaft and layshaft. This doubles the number of indirect gear ratios available.
B- Another system is to use an auxiliary gearbox behind the main gearbox with a choice of direct drive or a reduction to split the ratios in the main gearbox. This enables all the available gears to be used in sequence. The auxiliary gearbox may be a layshaft type with constant-mesh gears, or epicyclic, and the gear change may be power-operated electrically or by compressed air.

OVERDRIVE GEAR:

Sometimes, and particularly, for cars where economy with a lowered cursing engine speed is desired, the epicyclic unit may provide an overdrive of approximately 0.75:1. More recent practice is to incorporate fifth speed an indirect ratio of some 0.75:1 to 0.85:1. A typical arrangement is an extra pinion on the layshaft in constant mesh with a mineshaft pinion turning on needle-roller bearings. This is engaged by a synchromesh unit splined to the mainshaft and operated from the reverse selector.

THE ALL-INDERCT GEARBOX (TRANSAXLE):

The layshaft two-stage gearbox is used in both longitudinal- and transverse-engined front-wheel-drive case. However, many of the former employ a single-stage, all-indirect gearbox. There is no direct drive and consequently no particular advantage in 1:1 gearbox ratio.

TWO-SPEED TRNASFER GEARBOX:

A range of vehicles uses optional four-wheel drive- with additional ‘emergency’ low ratios- to provide a cross-country facility. This is usually accomplished by a two-speed transfer gearbox. With layshaft and two pairs of constant-mesh helical gears, attached to the end of the main gearbox are driven via short coupling shaft from the gearbox mainshaft.

Four- and All-Wheel Drive:

Four-wheel-drive (4WD) and all-wheel-drive (AWD) systems can dramatically increase vehicle’s traction and handling ability in rain, snow, and off-road driving. The improved traction of 4WD and AWD systems allows the use of tires narrower than those used on similar 2WD vehicles. These narrow tires are less expensive. They also tend to cut through snow and water rather than hydroplane over it. Both 4WD and AWD systems add initial cost and weight.

4WD versus AWD:

4WD systems are those having a separate transfer case. They also give the driver the choice of operating in either 2WD or 4WD through the use of a shift lever or shift button.

AWD systems do not have a separate transfer case. They use a front-wheel-drive transaxle equipped with a viscous clutch, center differential, or transfer clutch. All-Wheel-drive system does not give the driver the option of selecting 2WD or 4WD modes. The system operates in continuous 4WD. All-wheel-drive vehicle are usually passenger cars that are not designed for off-road operation. They are designed to increase vehicle performance in poor traction situations, such as icy snowy roads, and in emergencies.

Gear Geometry and Applied Theory

This revised, expanded edition covers the theory, design, geometry, and manufacture of all types of gears and gear drives. An invaluable reference for designers, theoreticians, students, and manufacturers, the second edition includes advances in gear theory, gear manufacturing, and computer simulation. Among the new topics are: new geometry for gears and pumps; new design approaches for planetary gear trains and bevel gear drives; an enhanced approach for stress analysis; new methods of grinding and gear shaving; and new theory on the simulation and its application.

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التلامس بين التروس gearing contact

IDEAL CONTACT
Pattern is spread evenly over tooth's profile with concentration nearer toe than heel.

COMPETITION CONTACT
Pattern concentrated just up from the toe covering 1/3 to 1/2 of the tooth.

HIGH CONTACT

Pattern is concentrated at the crown of the drive gear tooth.

Move the pinion deeper in towards the differential carrier (add pinion shim

LOW CONTACT

Pattern is concentrated in the root of the drive gear tooth.

Move the pinion out away from the differential carrier (subtract pinion shim

HEEL CONTACT
Pattern is concentrated off the heel end of the drive gear tooth.

Move the ring gear closer to the pinion (decrease backlash) while maintaining minimum backlash.

TOE CONTACT
Pattern is concentrated off the toe end of the drive gear tooth.

Move the ring gear away from the pinion (increase backlash) while maintaining minimum backlash

هااااااااام Gear Geometry

Gears: An Introduction
Gears are a means of changing the rate of rotation of a machinery shaft. They can also change the direction of the axis of rotation and can change rotary motion to linear motion.
Unfortunately, mechanical engineers sometimes shy away from the use of gears and rely on the advent of electronic controls and the availability of toothed belts, since robust gears for high-speed and/or high-power machinery are often very complex to design. However, for dedicated, high-speed machinery such as an automobile transmission, gears are the optimal medium for low energy loss, high accuracy and low play.
Gears are of several categories, and can be combined in a multitude of ways, some of which are illustrated in the following figures.

Meshing Circular Spur Gears

Rack and Pinion Spur Gears

Circular Worm Gear and Mating Cylindrical Worm

Inside Spur Gear withMating Pinion Spur Gear

Gears have existed since the invention of rotating machinery. Because of their force-multiplying properties, early engineers used them for hoisting heavy loads such as building materials. The mechanical advantage of gears was also used for ship anchor hoists and catapult pre-tensioning.
Early gears were made from wood with cylindrical pegs for cogs and were often lubricated with animal fat grease. Gears were also used in wind and water wheel machinery for decreasing or increasing the provided rotational speed for application to pumps and other powered machines. An early gear arrangement used to power textile machinery is illustrated in the following figure. The rotational speed of a water or horse drawn wheel was typically too slow to use, so a set of wooden gears needed to be used to increase the speed to a usable level.

An 18th Century Application of Gears for Powering Textile Machinery

The industrial revolution in Britain in the eighteenth century saw an explosion in the use of metal gearing. A science of gear design and manufacture rapidly developed through the nineteenth century. Today, the most significant new gear developments are in the area of materials. Modern metallurgy has greatly increased the useful life of industrial and automotive gears, and consumer electronics has driven plastic gearing to new levels of lubricant-free reliability and quiet operation.

Nomenclature of Common GearsSome intermesh terms of common gears are illustrated in the following two figures.

Nomenclature of Bevel Gears
Some terms commonly used for bevel gears are annotated in the following figure.

To obtain the gear ratio, TV = (output rate)/(input rate), of a compound gear train, an illustrated example is presented in this section.
The procedure is to start with the input, and to calculate how the angular velocity propagates through each successive intermeshing pair of gears based upon the number of teeth.
Consider a compound gear train below.

Suppose that the input gear speed (rotation rate) is 1600 rpm clockwise, i.e.,

The gear ratio between w1 and W2 is inversely proportional to the teeth numbers, n, i.e.,

Hence,

where the negative sign represents for counter-clockwise direction.
Similarly,

and

The final gear ratio TV can thus be obtained,

Epicyclic gear trains are powerful when used correctly, but are often misunderstood. Illustrated below is a typical epicyclic gear train. Notice how the planet gears roll on and revolve about the sun gear. The ring gear rolls on the planet gears. Such a gear configuration has useful applications, but the overall gear ratio is quite difficult to intuitively calculate. Please select "Epicyclic Ratio Calc'n" to learn about an effective yet simple method for calculating the overall gear ratio.

نظرية ماكينات

Gears Types



Gears are categorized into several types. They are used in a wide era of industries including automotive, milling, paper industry etc. According to different applications in industries and different materials used they are categorized separately. Different types of gears are also custom design and are fabricated by gear manufacturing services as par the specifications









1- Angular Bevel Gears









These are bevel gears whose shafts are set at an angle other than 90 degrees. They are useful when the direction of a shaft's rotation needs to be changed. Using gears of differing numbers of teeth can change the speed of rotation.

These gears permit minor adjustment of gears during assembly and allow for some displacement due to deflection under operating loads without concentrating the load on the end of the tooth. For reliable performance, Gears must be pinned to shaft with a dowel or taper pin.



The bevel gears find its application in locomotives, marine applications, automobiles, printing presses, cooling towers, power plants, steel plants, defence and also in railway track inspection machine. They are important components on all current rotorcraft drive system.









2- Bevel Gears









They connect intersecting axes and come in several types. The pitch surface of bevel gears is a cone. They are useful when the direction of a shaft's rotation needs to be changed. Using gears of differing numbers of teeth can change the speed of rotation. They are usually mounted on shafts that are 90 degrees apart, but can be designed to work at other angles as well.



These gears permit minor adjustment during assembly and allow for some displacement due to deflection under operating loads without concentrating the load on the end of the tooth. For reliable performance, Gears must be pinned to shaft with a dowel or taper pin. Bevel gear sets consist of two gears of different pitch diameter that yield ratios greater than 1:1.





Types



The teeth on bevel gears can be straight, spiral or bevel. In straight bevel gears teeth have no helix angles. They either have equal size gears with 90 degrees shaft angle or a shaft angle other than 90 degrees. Straight bevel angle can also be with one gear flat with a pitch angle of 90 degrees. In straight when each tooth engages it impacts the corresponding tooth and simply curving the gear teeth can solve the problem. Spiral bevel gears have spiral angles, which gives performance improvements. The contact between the teeth starts at one end of the gear and then spreads across the whole tooth. In both the bevel types of gears the shaft must be perpendicular to each other and must be in the same plane. The hypoid bevel gears can engage with the axes in different planes. This is used in many car differentials. The ring gear of the differential and the input pinion gear are both hypoid. This allows input pinion to be mounted lower than the axis of the ring gear. Hypoid gears are stronger, operate more quietly and can be used for higher reduction ratios. They also have sliding action along the teeth, potentially reducing efficiency.





Applications



A good example of bevel gears is seen as the main mechanism for a hand drill. As the handle of the drill is turned in a vertical direction, the bevel gears change the rotation of the chuck to a horizontal rotation. The bevel gears in a hand drill have the added advantage of increasing the speed of rotation of the chuck and this makes it possible to drill a range of materials.



The bevel gears find its application in locomotives, marine applications, automobiles, printing presses, cooling towers, power plants, steel plants, defence and also in railway track inspection machine. They are important components on all current rotorcraft drive system.



Spiral bevel gears are important components on all current rotorcraft drive systems. These components are required to operate at high speeds, high loads, and for an extremely large number of load cycles. In this application, spiral bevel gears are used to redirect the shaft from the horizontal gas turbine engine to the vertical rotor.









3- Crown Wheel









A crown wheel is a wheel with cogs or teeth set at right angles to its plane. The internal diameter of a crown wheel is ground by holding the component in pitch like chucks to ensure accuracy of the finished gear



As a result of the development of "flat" crown wheels it has become possible to construct a special gearbox. IHC has used these new gearwheels to produce a prototype of a continuously variable speed gearbox.





Applications



Crown wheels are used in motorcycle automotive gearboxes. It is also used in mechanical clocks. The clock consists of a crown wheel, rotated by a falling weight, whose teeth drive the pallets of a verge backward and forward. This verge is connected to an arm with a hammer on the end that struck the bell.









4- Crown Wheel and Pinion









A crown wheel is a wheel with cogs or teeth set at right angles to its plane and the pinion is a small cogwheel that meshes with the crown wheel. Crown wheel and pinion have excellent heat distortion control, high strength, wear resistance property and noiseless and vibration free operation. They are made of fine-grained steel billet.



The pinion thread is specially made on the thread grinder to ensure proper fitting. Tooth contact of a crown pinion is inspected on a Gleason machine at regular intervals of time for uniform hardness and adequate case depth. They are checked thoroughly for high spots because this ensures premature failure and noise-free operation. The crown wheel & pinion are paired and checked for centralized tooth bearing and desired proximity. An elliptoid contact pattern is ensured between the crown wheel and pinion.



In a machine, when any torque is applied to the drive unit, the tendency is for the crown wheel and pinion to be forced into or out of mesh by the sliding contact. The amount of pre-load on the bearings determines how much torque can be transmitted without allowing end float, which cause the meshing of the gears to become incorrect.





Application



Crown wheel & pinion are used widely in automotive industries. They are one of the most stress prone parts of a vehicle. They are used in automobiles to maintain forward motion. To maintain forward motion both output drive shaft sides covers are removed and the pinion and crown wheel are swapped completely with differential.









5- Differential Gears









Differential gears link two shafts with a covering, forcing the total of the rotational angles of the shafts to be the same as the rotational angles of the covering. Arrangement of the system is done in such a way that one axle turns faster than the other.



When a differential gear is meshed with the other gear then the highly efficient torque is applied from the differential side gears to the axle shaft. When torque level decreases then the gear separating forces also decreases allowing the axle shaft to rotate independently. Differential gears can add or subtract the movement of two inputs. In practical terms, they will turn the number of revolutions proportional to the movements of both inputs. They are used to convert the lengthwise flow of power from the engine through the clutches, transmissions, and propeller shafts into a right-angle direction. This change allows the engine power to turn the wheels.



In the differential gears there are two coaxial gears, the pinions and the turntable. Pinions are mounted on intermediate shafts and these shafts are connected to a fixed carrier called the turntable. The differential gears are lubricated with a fluid that absorbs heat and increases the life and performance of the gears as well as the wheel. Regular driving subjects the fluid to high heat that breaks the fluid at a later stage. This results in the contact of two metals, which eventually increases the heat and prevents the gear from turning the car's wheel. So, the fluid should be properly checked in regular intervals.





Types of Differential Gears

There are two designs of differential gears, hypoid and spiral.

Spiral Differential - In spiral differential the pinion gears contacts the ring gears at its centerline .

Hypoid Gear - In the hypoid the pinion gear contacts the ring gear below the centerline. The size of pinion gear in hypoid differential is much smaller and the contact ratio is high, comparatively hypoid differential is much stronger than the spiral differential.





Applications



Differential gears in automobiles are the most common application of these gears. When the car is moving in a straight line, there is no movement of the differential gear with respect to its axis but when the car takes a turn then these gears help two wheels of the car to rotate differentially with respect to each other. When one wheel is stationary then the counterpart wheel rotates at twice of its expected speed.









6- Fine Pitch Gears









They are widely used in aerospace, nuclear and medical industries. They are available in plastic, steel, stainless steel and brass. They are used largely to transmit motion rather than power. They have high tooth strength.



Fine pitch gears are inspected by functional testing on a variable-center-distance fixture. They do not lend themselves to the kind of detailed tooth measurements because of their small dimensions.



Fine pitch gear is used widely in oil industry and for automotive transmission.









7- Girth Gears









The girth gear has been preferred over the gearless drives due to their lower initial cost, simplicity to install, operate and maintain. In the past many years girth gears have gone through enormous improvements.



They have high efficiency and the overall life of these gears depends upon proper lubrication and alignment. They are high quality, high precision component. The capital cost of girth gears is lower than others and they take less time to install. They are physically big and due to this they are unable to store for longer periods of time.



Girth gear materials have made several changes on their own. Casting is enhanced using full ring risering techniques. Simulation programs are installed for verification of proper solidification. New materials are used with an added advantage of increase in hardness and therefore increased ratings.



The girth gear is the heart of most mills and kiln drive system. They can't be used in spare parts inventory. They are also used in steel industry, sugar industry, paper and pulp industry.

Hardened and Ground Gears









Hardened and ground gear has two types of shaft arrangements. They can be parallel shaft type or hollow shaft type. Hardened and ground gear delivers a maximum hob rotation and table rotation with excellent machining accuracy. Hardened ground gear provide a noise free and long term operation. They are characterized by high output, easy operation and precise machining. They offer rigidity, strength and high resistance to shock load. They are available in a wide range of sizes and gear ratios.



Hardened gears are used in several essential machine tools like wheels, bedways, etc. and are widely used in the aerospace industry.









9- Helical Bevel Gears









Helical bevel gear is a toothed gear in angular design. The input side is provided with a motor flange or a free input shaft and the output side are provided with a free shaft end or a hollow shaft. Helical bevel gears are fitted with flanges of various sizes. Reciprocating tools cuts them.



The advantages of helical bevel gears are high efficiency and low reduction rate. The use of helical bevel gear saves energy and cost. Helical bevel gears are manufactured by an alloyed case hardening steel. The gear material is given an extremely strong, homogeneous structure.



They can replace worm gears in a variety of applications, particularly in modular machinery. They are also used as storage and retrieval unit. They are commonly used in modern differentials.







10- Helical Gears









Helical gears connect parallel shifts but the involute teeth are cut at an angle to the axis of rotation. Two mating helical gears must have equal helix angle but opposite hand. They run smoother and more quietly. They have higher load capacity, are more expensive to manufacture and create axial thrust.



Helical gears can be used to mesh two shafts that are not parallel and can also be used in a crossed gear mesh connecting two perpendicular shafts. They have longer and strong teeth. They can carry heavy load because of the greater surface contact with the teeth. The efficiency is also reduced because of longer surface contact. The gearing is quieter with less vibration.





Gear Configuration



They can be manufactured in both right-handed and left-handed configurations with a helix angle to transmit motion and power between non-intersecting shafts that are parallel or at 90 degrees to each other. For shaft at 90 degrees, the same helix angles are used and the tooth contact area of the gear is very small. If the angle of gear teeth is correct, they can be mounted on perpendicular shaft by adjusting the rotating angle by 90 degrees. The inclination of the teeth generates an axial force. As the angle of inclination increases the axial force also increases. Thrust bearings can counter these forces.





Applications



These are highly used in transmission because they are quieter even at higher speed and are durable. The other possible applications of helical gears are in textile industry, blowers, feeders, rubber and plastic industry, sand mullers, screen, sugar industry, rolling mills, food industry, elevators, conveyors, cutters, clay working machinery, compressors, cane knives and in oil industry.





Disadvantage



A disadvantage of helical gear is the resultant thrust along the axis of the gear, which needs to be accomodated by appropriate thrust bearings. This can be overcome by the use of double helical gears by having teeth with a 'v' shape.









11- Herringbone Gears









They conduct power and motion between non-intersecting, parallel axis that may or may not have center groove with each group making two opposite helices. The two helix angle come together in the center of the gear face to form a 'V'. in these gears the end thrust forces cancel themselves out. Its difficult to cut this type of gear but its made easier by machining a groove in the face at the point of the apex of the 'V' creating a break in the middle of the herringbone gear teeth. They do not have any separating groove between the mirrored halves.





Action is equal in force and friction on both gears and all bearings. Herringbone gear also allow for the use of larger diameter shaft for the same volumetric displacement and higher differential pressure capability.



The most common application is in power transmission. They utilize curved teeth for efficient, high capacity power transmission. This offers reduced pulsation due to which they are highly used for extrusion and polymerization. Herringbone gears are mostly used on heavy machinery.









12- Master Gear









They offer high precision, low volume productions. They are used for composite testing of production components. They have high speed, quiet operation, longer life and greater efficiency.



The most common applications are as setting masters and rolling masters for inspection and production applications. They are used to determine the accuracy of work gears. When master gears and work gears are rolled together on rolling fixtures dimensional variations are determined by various indicators, charts or other indicating devices. Master Gears are also used in aerospace and automotive industry.









13- Mill Headers









Mill headers find heavy usage in industrial sectors as an essential part of various vehicles and machines. They are used in various industrial sectors including coal and mining, oil exploration, paper mining, chemical industries, cement plant industry, sugar mill and many more. In industrial sectors these gears are used as an important part of conveyors, cranes, elevators, separators and kilns because they offer high power-density and modularity.






14- Miter Gears









Miter gears are bevel gears put together with equal numbers of teeth and axes that are usually at right angles. Miter is the surface forming the beveled end or edge of a piece where a miter joint is made.



Miter gears are cut with a generated tooth form that has a localized lengthwise tooth bearing. They are offered in various modules, number of teeth, speed ratio, materials and designs. Miter gears are made of steel, brass, bronze, aluminum, nylon and duracon.





Features



They are known for efficient power transfer and durability. They can carry heavy loads and can eliminate secondary operations that are useless during the process. They are used in drilling air holes in vacuum molds, drilling radial ports in door closers, milling oil grooves and act as a low cost spindle for dedicated machines.



They are designed for the efficient transmission of power and motion between intersecting shafts at right angles. They can be of two types, ground spiral miter gear and spiral miter gear. They give smoother, quieter operation. They handle higher speeds and greater torque loads. They provide a steady ratio.





Applications



Miter gears are also used in printing, agriculture, bottling, and material handling and steering. They are used in various industrial sectors including-coal and mining, oil exploration, paper mining, chemical industry. They are used as important parts of conveyors, elevators and kilns.









15- Non-Involute Gears









Non-involute gears have reduced specific sliding. Reduced gear sliding has an affect on low speed meshes, where sliding losses predominate. The efficiency of these gears is also increased by the use of less viscous oil.



The tooth profile geometry is uniquely defined by the arc shaped path of contact. The gears manufactured by the same rack cutter have the concave convex mesh. The result of enlarged reduced radius of curvature has as a consequence reduced pressure and better lubrication conditions. The geometry of non-involute gear tooth provides substantially higher capacity than any other gearing.



The disadvantages of the non-involute gearing are lower transverse contact ratio and great sensitivity to the center distance accuracy.









16- Pinion Gears









It is a small cogwheel. The teeth fit into a larger gear wheel. Rotational motion is converted into linear motion when the pinion turns and moves the rack. Pinion gears are engineered to be the best gears.



Pinion gear system involves the use of a small round gear called pinion and a large flat gear called rack, more the number of teeth in the pinion gear, more is the speed of rotation. Pinion with smaller number of teeth produces more torque. Pinion is attached to the motor shaft with glue. Rotation of pinion is done by rotation of pinion about a fixed center that helps the rack to move in the straight line. If the rack is moved and the pinion rotates then the center of the pinion moves taking along the pinion with it.









17- Rack Gears









Rack gear is a toothed bar into which a pinion meshes. Racks are gears of infinite pitch radius. They are used to translate rotary motion to linear motion or vice versa. They will mesh with pinions of the same pitch.



Racks are made of various materials. The commonly used materials for racks are stainless steel, brass, and plastic.



They are widely used in automobiles. The steering wheel of a car rotates the gear that engages the rack. The rack slides right or left, when the gear turns, depending on the way we turn the wheel. Windshield wipers in cars are powered by a rack and pinion mechanism. They are also used in some scales to turn the dial that displays weight.







18- Ring Gear and Pinion









It is one of the most commonly used spiral bevel gears, used largely in automotive industry. In order to enable the axle ratio setting a vehicle must be must be equipped with a racing gearbox, also known as ring and pinion gears.



A ring and pinion gear set is expensive to buy and install, requiring highly skilled technicians. This gear is hypoid, it not only rotates against each other but also wipe across the drive surfaces, creating the shearing force that cuts the lubricants changing its viscosity. Gear oil used here is heavy and the thickness of the oil changes with the temperature. There are bearings in the final drive, among which two support the drive pinion and two support the case that holds the ring gear and one on each axle nearest the wheel.



To compute a new gear ratio, one needs to enter the stock ring pinion gears ratio along with the old and new tier size. It is also used in calculating the tier width and the speed of wheels.





Applications



It is used in heavy truck differentials. It is also used in tire rotation, wheel alignment and tire balance. It is one of the greatest masterpieces in automotive mechanism. It works for higher driving and loading capacity in the drive line from transmission to wheels. It is also used to compensate for discrepancies in the respective rotation rate of the drive wheels between inside and outside wheels during cornering for limited effective torque to the wheels with lower coefficient of friction.









19- Spiral Bevel Gears









Spiral bevel gears have spiral angles, which gives performance improvements. They are designed for an angle change of 90 degrees, where the two axes are concurrent and in the same plane. These gears have a double function of being helical and beveled at the same time. The contact between the teeth starts at one end of the gear and then spreads across the whole tooth. In this type of gears the shaft must be perpendicular to each other and must be in the same plane.



They are the most complex forms of bevel gears. The teeth are curved by cutting them obliquely, resulting in higher overall contact ratios. Because of higher contact ratio, these have better load carrying capacity an this allows them to be smaller in size for a given load capacity than an equivalent gear. Thus they can transmit more power with smaller gears.





Methods of Manufacturing



Face milled and face hobbed are two methods of manufacturing for spiral bevel gears. In the method of face milled, the grinding of the contacting surface is the last step. Whereas, in the face hobbed method, hard cutting is the final step. The same machine is used to rough cut and finish cut the gears. The desirable design of the gear is to minimize the weight of the gear and it is done by reducing the material in the gear's rim.





Applications



Spiral bevel gears are important components on all current rotorcraft drive systems. These components are required to operate at high speeds, high loads, and for an extremely large number of load cycles. In this application, spiral bevel gears are used to redirect the shaft from the horizontal gas turbine engine to the vertical rotor. They are also used in power windows and power seats. They are used where speed and strength are desirable along with the change in angle of power flow.









20- Spur Gears









They connect parallel shafts, have involute teeth that are parallel to the shaft and can have internal or external teeth. They cause no external thrust between gears. They are inexpensive to manufacture. They give lower but satisfactory performance. They are used when shaft rotates in the same plane.



The main features of spur gears are dedendum, addendum, flank, and fillet. Dedendum cylinder is a root from where teeth extend, it extends to the tip called the addendum circle. Flank or the face contacts the meshing gear, the most useful feature if the spur gears. The fillet in the root region is kinetically irrelevant.





Characteristics



The speed and change of the force depends on the gear ratio, the ratio of number of teeth on the gears that are to be meshed. One gear among the two is on the input axle, the axle of the motor and the other gear of the pair is on the output axle, the axle of the wheel.



They have higher contact ratio that makes them smooth and quiet in operation. They are available for corrosion resistant operation. They are among the most cost-effective type of gearing. They are also used to create large gear reductions.





Materials



They are available in plastic, non-metallic, brass, steel and cast iron and are manufactured in a variety of styles. They are made with many different properties. Factors like design life, power transmission requirements, noise and heat generation, and presence of corrosive elements contribute to the optimization of the gear material.





Applications



Generally used in simple machines like washing machines, clothes dryer or power winches. They are not used in automobiles because they produce sound when the teeth of both the gears collide with each other. It also increases stress on the gear teeth. They are also used in construction equipment, machine tools, indexing equipment, multi spindle drives, roller feeds, and conveyors.









21- Straight Bevel Gears









Straight bevel gears are the simplest of the bevel gears. They are manufactured on precision generating machines by indexing method ensuring that the teeth should be of tapered depth and thickness. Teeth are cut on the outside of the cone. They have a straight tooth geometry, which if extends, passes through the intersection of their axes.



Straight bevel angle can also be with one gear flat with a pitch angle of 90 degrees. These have conical pith surfaces that operate on intersecting axes. They can be designed and cut to operate on any shaft angle. In straight bevel gears when each tooth engages it impacts the corresponding tooth and simply curving the gear teeth can solve the problem.



Straight bevel gears come in two variations depending on the fabrication equipment. They are grouped into Gleason type and the standard type. Major percentage of them is of Gleason type with a coniflex form that gives almost an imperceptible convex appearance to the tooth surface. In the standard form, the gear has no profile shifted tooth.



These gears are recommended at less speed and when loads are light. At higher speed they make noise. The most preeminent function of these gears is in a bevel gear differential. Straight tooth gears are also used in chemical industries, steel plant, machine tools, cement plant, textile processing, material handling system, sugar mills and cooling towers etc.








22- Support Rollers









Support rollers are the kind of gears that provide support to cable and other related products. They are used to muffle vibration noise. Many support rollers in web manufacturing plants are driven to rotate by the friction between the roller surface and the web. At higher speed operation, air film between the roller surface and the web can be large enough to cause slippage. Therefore, it is important to keep the friction torque of the roller bearings very small. Putting rollers close together can decrease pulling tension.



Over time wear conditions develop on the surfaces of the support rollers making it difficult to control the axial thrust of the kiln with moderate support roller adjustments. The wear can also cause high surface stress conditions and higher hertz pressures as the wear progresses. The extent of wear is directly proportional to the amount of support roller adjustment needed to control the axial thrust of the kiln. Resurfacing enables proper adjustment of the conveyor rollers, decreased power consumption and therefore lower operating cost.



Support rollers are used in industries as an important component in conveyors, elevators, rollers etc.









23- Tacho Drives









Tacho drive is the black sheaved cable that goes over the starter at 90° and is held to the engine by a large nut. There is a small oil seal in the tach drive on the engine clock. Tacho cable are used in orbital motors.









24- Thrust Rollers









Thrust rollers are hydraulic 3dimension movable rolls. Thrust rollers limit the lateral movement of the rotating debarking drum and help maintain equipment balance. They provide load compensation and are used to accommodate uneven loads.



There are several types of thrust rollers. They can be single and double acting, combination roller and cross rollers.



Inspection of the load bearing surface or the thrust rollers should be done at regular intervals to avoid slow and faulty operations. Thrust rollers can be refurbished and problems like timing marks taper wear and irregular face profiles can be eliminated.









25- Idler Gear









A gear wheel placed between two other gears to transmit motion from one to the other. It does not alter the speed of the output, but it does alter the direction it turns. It is used to ensure that the rotation of two gears is the same. An idler gear is placed between two gears. The idler gear rotates in the opposite direction as the driver gear, and the follower gear rotates in the opposite direction of the idler, the same direction of the driver. It is also used to change the spacing between the input and output axles. It does not change the gear ratio between the input and output gears.



All the gears and wheels that turn inside the treads of a battle tank are all idler gears that transfer power from the input gear to the output gear to move the tread and move the tank forward.



The power take off mechanism includes a gear train with an input idler gear, a first intermediate idler gear, a second intermediate idler gear and an output gear. The input idler gear receives a rotary input and the first intermediate idler gear meshes with the input gear and the second intermediate idler gear. The output gears transmit rotary power to one of the first and second axles.









26- Gear Trains









A gear train is two or more gear working together by meshing their teeth and turning each other in a system to generate power and speed. It reduces speed and increases torque. To create large gear ratio, gears are connected together to form gear trains. They often consist of multiple gears in the train. The smaller gears are one-fifth of the size of the larger gear. Electric motors are used with the gear systems to reduce the speed and increase the torque. Electric motor is connected to the driving end of each train and is mounted on the test platform. The output end output end of the gear train is connected to a large magnetic particle brake that is used to measure the output torque.



Simple Gear Train - The most common of the gear train is the gear pair connecting parallel shafts. The teeth of this type can be spur, helical or herringbone. The angular velocity is simply the reverse of the tooth ratio. The main limitation of a simple gear train is that the maximum speed change ratio is 10:1. For larger ratio, large size of gear trains are required; this may result in an imbalance of strength and wear capacities of the end gears.



The sprockets and chain in the bicycle is an example of simple gear train. When the paddle is pushed, the front gear is turned and that meshes with the links in the chain. The chain moves and meshes with the links in the rear gear that is attached to the rear wheel. This enables the bicycle to move.



Compound Gear Train - For large velocities, compound arrangement is preferred. Two keys are keyed to a single shaft. A double reduction train can be arranged to have its input and output shafts in a line, by choosing equal center distance for gears and pinions.



Epicyclic Gear Train - It is the system of epicyclic gears in which at least one wheel axis itself revolves around another fixed axis.



Planetary Gear Train - It is made of few components, a small gear at the center called the sun, several medium sized gears called the planets and a large external gear called the ring gear. The planet gears rolls and revolves about the sun gear and the ring gear rolls on the planet gear. Planetary gear trains have several advantages. They have higher gear ratios. They are popular for automatic transmissions in automobiles. They are also used in bicycles for controlling power of pedaling automatically or manually. They are also used for power train between internal combustion engine and an electric motor.





Applications



Gear trains are used in representing the phases of moon on a watch or clock dial. It is also used for driving a conventional two-disk lunar phase display off the day-of-the-week shaft of the calendar.









27- Planetary Gear









These are a set of gears usually two or more on or inside a larger gear. They make drastic gear ratio possible. They are used when one wishes to turn the input in the same direction as the output. The gear in the center of the larger gear, called the sun engages two or three smaller gears placed in the same large gear. These small gears are called planet and they are engaged to the inside of the large gear called the ring. Planet gears turn on movable center and the sun gears turn on a fixed center.





Gearing Mechanism



In a planetary gearing, the member which receives motion from outside the mechanism is called the driver; the member from which motion is taken outside the mechanism is called the follower; the member which carries one or more bearing pins about which the planet gears rotate is called the train arm. There is only one member that is maintained in a fixed position. Planetary gears are also used to produce different gear ratios depending on the which gear is used as input, which one as output and which one is held stationary.





Applications



An automatic transmission uses planetary gearsets to create different gear ratios using clutches and brake band to hold different parts of the gearset stationary and change the input and the output.



Planetary gears are most commonly used gear train. Planetary gear trains have several advantages. They have higher gear ratios. They are popular for automatic transmissions in automobiles. They are also used in bicycles for controlling power of pedaling automatically or manually. They are also used for power train between internal combustion engine and an electric motor.









28- Ground Gear









Ground gear was first made with the advent of trawling. Throughout the history of trawling, various types of ground gears have been developed, gradually extending the range of trawlable bottoms. Until 1985, the predominant type of ground gear mounted on bottom trawls consisted of rolling bobbins, threaded on a chain that ran through holes in their centers. In the mid 80s, Rockhopper ground gear was developed and adopted by a number of major trawl fisheries, and nowadays this type of gear is virtually exclusively used by fisheries all over the world.



Ground gear teeth are crowned with the ideal amount of tip and root relief to ensure quiet operation. They assure high transmission accuracy and comply with grade one quality to take up peripheral velocity of 1.5 meters per second. They offer maximized efficiency, higher load capacity, correction of profile, and longer life.



Ground gears are widely used in fishing industry.

- Face Gear









Face gears are the gear wheel with cogs mortised into its face, usually in conjugation with a lantern pinion. Face gear enables the transmission of drive through an angle. Their use in high power, high precision applications have become popular. Face gears have high strength teeth and good contact geometry, which give high torque capability.



Face gears help to ensure accuracy and rigidity. It is generated by a shaper cutter with the same diametrical pitch and pressure angle as the pinion. Pressure angle of a face gear is calculated by calculating the shape of the tooth, the frontal pressure angle.





Features



Face gears are of three types; standard face gear, helical face gear, and offset face gear. Face gears have many advantages. The pinion is a normal spur gear and assembly time is reduced because only the axial position of the face gears needs to be set. In this there is no axial load on a pinion with straight spur teeth and the meshing is smoother due to oblique contact lines and high contact ratio. It can easily obtain zero backlash transmission.





Applications



They are used in aerospace drive system. They are used to transfer power between intersecting shafts as found in helicopter rotor transmission. They are also effective with insufficient lubrication, thus increasing the reliability of the aircraft. They also work with bad alignment between pinion and the rotor gear. Helicopters using transmission systems based on face gear have a higher safety and survivability. Face gears are supplied in wholesale to the aerospace industries.









30- Internal Gears









Internal gears have cylindrical pith surface with teeth parallel to the axis. Gears make an internal contact with these gears. They have the teeth cut on the inside of the rim rather than the outside. When they are used with the pinion more teeth carry the load and are evenly distributed. This even distribution decreases the pressure intensity and increases the life of the gear. The center distance of a given velocity is shorter.



Internal gears are hollow. The properties and teeth shape is similar as of external gears except that the internal gear had different addendum and dedendum values modified to prevent interference in internal meshes. They are designed to accommodate a wide range of equipment. These are ideal and cost effective. The teeth are cut into the inside diameter while the outside diameter is smooth. These gears are available only in brass. Internal gear offers low sliding and high stress loading. They are used in planetary gears to produce large reduction ratios.



When choosing a mating gear the difference between the number of teeth of girth gear and the pinion should not be less than 15. Their non-binding tooth design ensures smooth, quiet operation. They are used to transmit rotary motion between parallel shafts, the shaft rotating in the same direction as the arrangement.



The main applications of internal gears are in rollers, indexing, timing and other light duty applications. They are used as tools for creating solid models of drive components.









31- Cycloidal Gears









Cycloidal gears are used in pairs and are set at an angle of 180 degrees used to balance the load and are driven by multiple crank shafts to share the load and increase torsion rigidity. The cycloidal gear mesh with a large quantity of precisely ground steel pins. The combined tooth contact area of the two cycloidal gears and pins ensures that the load is distributed almost entirely around the pitch circle.



With cycloidal gearing the input and output remains in constant mesh. Cycloidal gearing provides considerable latitude in selection of operating characteristics-deceleration, dwell periods, ratio of input to output motions etc. In cycloidal gear if the output crank is to stop then the drive pin must be on the pitch circle of the planet gear to avoid reversing of the motion.





Gearing Mechanism



Cycloidal gearing requires two different curves to obtain conjugate action. Two gears are placed on either side of a roller. The roller is rolled along the outer edge of one of the gear wheels. The curve traced out from this initial point of contact is called epicycloid. The same roller is then rolled on the inside edge of the other gear wheel generating another curve called hypocycloid. These two curves will be conjugate to each other. The smaller roller disk is called the generating circle for the gear set.



For cycloidal gear to be interchangeable, circles of the same size must generate them. The teeth of a cycloidal rack are cycloid generated by the rolling generating circle. They are not straight and their shape depends on the radius of the generating circle.









32- External Gear











These are the most often used and the simplest gear system with cylindrical gears with straight teeth parallel to the axis. They are used for transmitting rotary motion between parallel shafts. When a smaller gear called the pinion, drives the larger gear called the wheel, also having external teeth, the corresponding driving and driven shafts rotate in opposite direction. The two gear surfaces come into contact once and so they are noisy at high speed.



External gears are generated with a tool moving forward towards the component axis. Internal gear cutter with very small diameter and few teeth is used for the production of external gear. External gears are widely used in various industrial sectors like coal industry, mining, steel plant, paper industry, and many more.









33- Winch Gears









Winch gears are used to convert the high speed, low force input of the handle into low speed, high torque output at the drum. These are quite highly developed and use tooth forms that are significantly different from those found in other gear applications such as car gearboxes and power transmission.



The loads on winch gears are actually high while the speeds they turn at are relatively very low. This results in thick strong teeth that resist high loads as well. The winch gears are not long lasting and have low efficiency. The winches turn few thousand times in their entire lives and they never go fast enough to get hot.





Applications



Winch gear is commonly used in boats and fleets. Before every operation winch gear should be lubricated. The ratchet should not be engaged when the winch gear is turning. They get worn out easily; overloading them and deforming the teeth causes majority of damage to the gears. For long term safety and security the damaged part should be replaced and full analysis of the cause of damage should be done.