BELT AND CHAIN DRIVE 

TOPIC: BELT AND CHAIN DRIVES

CONTENT

•       Definition

•       Types

•        Uses

 BELT DRIVES

A belt is a looped strip of flexible material used to mechanically link two or more rotating shafts. A belt drive offers smooth transmission of power between shafts at a considerable distance. Belt drives are used as the source of motion to efficiently transmit power or to track relative movement. When the belt is used for speed reduction, the smaller sheave is mounted on the high-speed shaft, like the shaft of an electric motor. The larger sheave is then put on the driven machine.

TYPES OF BELT DRIVES

The types of belt drives are diverse. The list of its kinds includes flat belts, synchronous timing belts, cog belts, vee-belts, round belts, multi-groove belts, ribbed belts, film belts, metal belts, endless round belts, and specialty belts. Some of them are explained below:

 1.     The Flat belt: The simplest type is often made from leather or rubber-coated fabric. The sheave surface is also flat and smooth, limiting the driving force by the pure friction between the belt and the sheave.

2.     Synchronous Belts, or Timing belts: These ride pockets that have mating grooves that the teeth on the belt seat. It is a positive drive, limited only by the tensile strength of the belt and the shear strength of the teeth.

3.    Cog Belts: These are applied to standard V-grooved sheaves. The cogs give the belt greater flexibility and higher efficiency compared with standard belts.

4.     Vee-Belts: The V-shape causes the belt to wedge tightly into the groove, increasing friction and allowing high torques to be transmitted before slipping occurs.

BELT AND PULLEY ARRANGEMENT

There are various types of belt and pulley arrangements. These include:

1.   Open belt: An open belt connecting two pulleys makes them run in the same direction

2.    Crossed belt; this changes the direction of pulleys.

3.     V-belt: V-belts run on V-pulleys. A common use of the V-belt and V-pulley is the fan belt of an automobile.

EVALUATION

1.      What is a belt drive?

2.    State the types of belt drive

3.     Explain each type of belt drive

CHAIN DRIVES

A chain is a power transmission element made as a series of pin-connected links. The design provides for flexibility while enabling the chain to transmit large tensile forces. A chain drive is a way of transmitting mechanical power from one place to another. When transmitting power between rotating shafts, the chain engages mating-toothed wheels, called sprockets.

TYPES OF CHAIN DRIVES

1.          Roller Chain Drives: The most common type of chain is the roller chain, in which the roller on each pin provides exceptionally low friction between the chain and the sprockets. A roller chain is classified by its pitch, the distance between corresponding parts of adjacent links. The pitch is usually illustrated as the distance between the centers of adjacent pins. Standard roller chain carries a size designation from 40 to 240.

2.          Conveyor Chain: Rollers sit proud of links and can roll along supporting surfaces It can be used for transporting materials, as rollers can support weight. Can also be used just to support the weight of the chain if transmitting power over long distances

3.          Inverted Tooth (or silent) Chain: Sprocket teeth mesh with shaped links instead of rollers on the chain. Joints between links use rolling rather than sliding contact. Profiles of links are more like involute gear teeth. The overall effect is to reduce noise.

4.          Leaf (or lifting) Chain: It is designed for lifting rather (than power transmission). Do not have to mesh with sprockets, hence no rollers. Therefore can be narrower than a roller chain with equivalent strength. Example: forklift truck.

EVALUATION

1.          What is a chain drive?

2.          State the types of chain drive

3.          Explain each type of chain