About our Precision Variable Speed Pulleys

Speed range is variable within standard ratio limits.  Standard ratio is 2.8:1.  All of our variable speed pulleys are spring-loaded and color-coded to indicate spring pressure - easy to identify and use.

Standard bore sizes are 5/8 to 3/4 and 14mm to 19mm for the VPSR pulleys. These pulleys combine strength and cost savings of a steel hub and mounting shaft; the pulley flanges are a combination of glass-reinforced nylon and steel pulley face.

Designed for belt sizes 1/2" V and horsepower ratings up to 3/4 HP.  They are engineered to offer an economical alternative for many applications that may not require the expense of AC/DC variable speed motors.

Torque Transmission Precision Variable Speed Pulleys

  • Economical
  • Lightweight
  • Strong
  • Quiet
  • Infinite speed range - within pulley ratio limits
  • Close tolerance on round shaft

Contact us with your specific Variable Speed Pulley requirements >>

Standard size, detailed dimensions and spring pressures are listed below.

Precision Variable Speed Pulley (VPSR) Engineering Specifications

Model Belt Speed
HP Rating
@ 1800 RPM
Pitch Dia.
VPSR-43 1/2" V Up to 2.8:1 3/4 1-21/32" Min
4.0" Max
1 lb. 11 oz.


Precision Variable Speed Pulley dimensions

Precision Variable Speed (VPSR) Pulleys Pulley Dimensions

Model A B C1
Standard Bores
5/8 3/4 14mm 19mm
VPSR-43 4-1/4 25/32 1 1/2 4-1/4
Non-Standard Bore sizes, both Inch and Metric are available upon request at no extra charge.  Please contact us

Precision Variable Speed Pulleys (VPSR) Spring Pressures

Model Spring Strength Color Code LBS. COMPRESSION IN SPRING
As Pulley Starts
to Open
Fully Open


Medium White 33 40

Download the Pulley Purchasing Checklist 

Precision Variable Speed Pulleys

Standard Tolerances for Bore Sizes, Keyways and Setscrews

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