Understanding Belt and Chain Drives

Belt Drives

Belt Drive Basics

A belt drive transmits rotational motion between two shafts using a flexible belt. The belt engages with pulleys on each shaft, allowing for power transmission. Belts must be flexible to handle initial tension and generate sufficient friction to prevent slippage.

Toothed Belt Drives

Toothed belt drives are efficient and used in various machines. They combine the advantages of flat belts, V-belts, chains, and gears while minimizing their drawbacks. These drives require no lubrication or maintenance. Toothed belts typically consist of fiberglass, neoprene, and a nylon coating.

Cable Drives

Steel Wire Rope (SWR) Drives

SWR drives use an endless steel cable wound between two pulleys, sometimes with intermediate supports. Kinematically similar to belt drives, SWR drives are suitable for high power transmission over longer distances and at higher speeds (up to 25 m/sec). Steel cables offer high tensile strength and negligible elongation. They are constructed by grouping individual wires (e.g., 7, 19, or 37 wires) to form strands, which are then combined (usually 6 strands) to create the cable.

Textile Cable Drives

Textile cables, often made of cotton fibers, provide resilience but are prone to fraying.

Common String Drives

Common strings are primarily used for lifting and traction, not high-speed power transmission. Their main function is load-bearing, not movement.

Chain Drives

Articulated Chain Drives

Articulated chains are commonly used for transmitting motion. Their construction ensures smooth and quiet operation. These chains engage with the teeth of sprockets mounted on the driving and driven shafts.

Articulated Chain Block Drives

Block or link chains are used in heavy-duty machines and conveyor lifts.

Modules and Pitch

Module

Used in the metric system, the module (m) is a value used to calculate sprocket dimensions. Units include meters (m), centimeters (cm), and millimeters (mm).

Pitch

Used in the English system, the pitch is the inverse of the module (M). The unit is typically inches per tooth (in/tooth) or simply inches.