PAES 301: Engineering Materials - V-Belts and Pulleys

Study Notes

V-belts transmit motion and power between shafts, featuring a trapezoidal cross-section.
V-pulleys consist of grooved rims designed for movement and power transfer via V-belts; their rims have an open-channel cross-section.
A V-belt drive includes multiple V-belts mounted on two or more V-pulleys for efficient power transmission.
Pulley diameter refers to the external diameter of the pulley, while pulley pitch diameter coincides with the belt pitch.
Belt pitch maintains consistent length when bent perpendicular to the base of the belt.
Belt length is measured where the belt's pitch is located.
Speed ratio refers to the angular velocity ratio of the pulleys, excluding slip and creep factors.
Belt speed indicates the linear speed of the belt at the pulley pitch diameter.

Flat belts are flat-surfaced power transmission devices that operate between pulleys.
Pulleys guide the flat belt in power transmission from one shaft to another.
Solid pulleys are constructed from a single piece, while split pulleys consist of two parts, allowing for easy installation and removal.
Crown pulleys feature a convex peripheral face, assisting in belt centration; level pulleys have a flat peripheral face.
Rubber belting, made from fabric or cord and vulcanized rubber, is known for moisture resistance and high tensile strength.
Power rating quantifies the power transmission capability of a belt per millimeter of its width, expressed in watts.
Ply indicates the number of layers in a belt, enhancing strength and durability.
Belt speed measures how fast the belt travels around pulleys, typically in meters per second.
Arc of contact specifies the degree portion of the belt making contact with the pulley.
Belt length includes the total length, considering tangents and arcs around pulleys.
Effective diameter is crucial for calculating drive parameters and represents the diameter in effective contact with the belt.

Crossed belt drives feature belts running in a crisscross pattern across pulleys.
Nylon cord belts combine strength and flexibility due to their construction.
Keyways are essential grooves in shafts or hubs that secure keys for torque transmission.
Bearing loads define the forces exerted on bearings due to pulleys and belt tensions.
Belt cross-sections vary in thickness and width, catering to diverse power transmission needs.
Enclosing the drive helps prevent accidental contact and keeps debris away from moving parts.
Drive inspection involves checking belt tension, the status of keys and setscrews, and the belt's overall condition.
Proper markings on belts and pulleys ensure identification and facilitate maintenance through size and manufacturer information.