BELTS & PULLEYS
Belts and pulleys
for top efficiency
I
ndustrial belt drives consist of rubber belts that wrap around drive pulleys, in turn driven by electric motors. In a typical setup, the belt also wraps around one or more idler pulleys that keep the belt taut and on track. The main reasons that engineers pick belt drives over other options is that modern varieties require little if no maintenance; they’re less expensive than chain drives; and they’re quiet and efficient, even up to 95% or more. In addition, the tensile members of today’s belts — cords embedded into the belt rubber that carry most the belt load — are stronger than ever. Made of polyester, aramid, fiberglass or carbon fiber, these tensile cords make today’s belt drives thoroughly modern power-transmission devices.
motioncontroltips.com | designworldonline.com
Belts & Pulleys — Power Transmission HB 05.19 V3.indd 15
Manufacturers generally describe belts and pulleys with five main geometries. Pitch diameter is the drive-pulley diameter. Center distance is the distance between the two pulleys’ centers. Minimum wrap angle is a measure of how much the belt wraps around the smallest pulley. Belt length is how long the belt would be if cut and laid flat. Finally, in the case of toothed belts (also called synchronous belts) the pitch is the number of teeth per some length — so a 3-mm pitch means that the belt has one tooth every 3 mm.
5 • 2019
Pulleys and sprockets need tight tolerances to deliver top performance. SDP/SI Shaftloc shaft locks work on narrow pulleys for tight enclosures, as the former has engineered dimensions to transmit more torque than clamp or setscrew connections. It’s a mechanical component that fixes pulleys without marring the shaft— for easy repositioning and synchronizing rotating components.
DESIGN WORLD — MOTION
15
5/14/19 8:42 AM
