GU-S87 Helical-Worm Gear Unit

The large helical-worm frame, in cast iron with finned flanks. Thermal limit rather than tooth strength usually sets the rating here, so check the duty cycle before selecting on torque alone.

How this frame is rated

The GU-S87 carries 820 Nm of rated output torque, calculated on tooth flank and root capacity to international gear rating standards at a service factor of 1.0. Ratios run from i 14.2 to i 301.5, which at 1450 rpm input puts the output shaft between 4.8 and 102.1 rpm. Motors from 0.55 to 7.5 kW bolt to the input.

With the largest listed motor the frame reaches its mechanical torque limit at about i 20.2. Below that ratio the motor governs and output torque still climbs with the reduction; above it the frame governs, and extra ratio buys you speed reduction only. That is the knee you can see on the characteristic chart further down this page.

What usually decides the selection

Thermal capacity is 8.9 kW of continuous throughput without auxiliary cooling at 20 °C ambient. Permissible radial force at the shaft mid-point is 10,800 N; move the load towards the shaft end and that figure falls quickly, so tell us where the pulley actually sits. Housing is Grey cast iron, protection IP65, and the unit weighs 78 kg dry.