The velocity ratio of an epicyclic gear train is determined by the following methods: (a) Tabulation method; (b) Formula method; and (c) Instant centre method or. Q. For a simple gear train, velocity ratio is the ratio of - Published on 06 Aug a. Speed of driving shaft and speed of driven shaft. b. Speed of driven shaft and. The velocity ratio of an epicyclic gear train is determined by the following methods: (a) Tabulation method; (b) Formula method; and (c) Instant centre method or.

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The third gear in the picture has 42 teeth.

### Types of Gear Train and Velocity ratio calculation

The idler gear serves to make both the drive gear and the driven gear rotate in the same direction, but confers no mechanical advantage. Belt drives[ edit ] Belts can have teeth in them also and be coupled to gear-like pulleys.

Special gears called sprockets can be coupled together with chains, as on bicycles and some motorcycles. Again, exact accounting of teeth and revolutions can be applied with these machines.

The output, eg the wheel of a buggy is connected to the driven gear.

## Types of Gear Train and Velocity ratio calculation | TechMiny

Spur gears The photograph below shows a simple gear train made up of a couple of spur gears. These are the common gears or cogs that look like wheels with teeth around the rim.

This involute curve is the path traced by a point on a line as the line rolls without slipping on the circumference of a circle. It may also be defined as a path traced by the velocity ratio of gear train of a string which is originally wrapped on a circle when the string is unwrapped from the circle.

## BBC - GCSE Bitesize: Gears: 1

The circle from which the involute is derived is called the base circle. In Figurelet line MN roll in the counterclockwise direction on the circumference of a circle without slipping. When the line has reached the position M'N', its original point of tangent A has reached the position K, having traced the involute curve AK during the motion.

As the velocity ratio of gear train continues, the point A will trace the involute curve AKC.

- The velocity ratio and train value of gear train:

For any instant, the instantaneous center of the motion of the line is its point of tangent with the circle. We have not defined the term instantaneous center previously.

### Gear train

When two bodies have planar relative motion, the velocity ratio of gear train center is a point on one body about which the other rotates at the instant considered.

When two bodies have planar relative motion, the instant center is the point at which the bodies are relatively at rest at the instant considered. The normal at any point of an involute is tangent to the base circle.

Because of the property 2 of the involute curve, the motion of the point that is tracing the involute is perpendicular to the line at any instant, and hence the curve traced will also be perpendicular to the line at any instant.

For chain drives, one can either use the number of teeth on the sprocket or the sprocket diameter. Assuming that there is no slippage, for the friction drives we can write: In this case, k will refer to the number of externally meshed rollers or in case of chain and pulley drives, it will refer to the number of crossed chains or belts.

An example is given below. Crossed belt Another type of simple gear train is the gear train that is used to change the output speed for a constant input velocity ratio of gear train.

## Gear train - Wikipedia

Most velocity ratio of gear train examples are the transmission boxes in cars or in machine tools. In general, they are called speed-change gear trains and they are made up of compound gear trains in which the output speed can be changed by meshing different gears in the train.

For each speed ratio one can treat the gear train as a different compound gear train and thus obtain the gear ratio for that particular arrangement. The compound gear train is defined as one or more gear mounted in same shaft.