POWER TRANSMISSION REFERENCE
GUIDE
Using synchronous belt drives
for positioning NEOPRENE
or polyester urethane or
synchronous belts (also called timing belts) with reinforcing tensile cords are widely used on rotary motion axes and other power transmission applications. Recall that timing belts are constructed much like flat and V belts plus have arrays of evenly spaced teeth on their inner surface to work via positive engagement. This kind of operation (core to chain and gear drives as well) is defined by almost zero relative differential of motion between the pulley or sprocket driving the belt and the belt itself. But besides their use for simple PT and rotary motion, the belts are also indispensable in two precision-motion application types: • Linear motion axes inside machinery necessitating servo-level motion control • Conveyors that need to position workpieces and other discrete items. The reinforcing tensile cords embedded in these belts are usually made of steel or Kevlar to prevent stretch, even when transmitting large torques and propelling loads with high acceleration; that complements the way in which the belt teeth prevent creeping because of their positive-drive nature. That’s especially true for urethane belts, which exhibit minimal tooth deflection.
Left: The synchronous belt here is a Poly Chain GT Carbon belt from Gates Corp. These excel on axes on low-speed high-torque machine in industrial applications. RIght: Shown is a small sampling of how the geometries of various synchronous belts differ. Some elements are tailored to English and metric designs; other features are industry-specific or even patented for improved power transmission and reliability on positioning axes.
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DESIGN WORLD — MOTION
5 • 2020
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