Roller chain
Leaf Chain
Block forged chain
Conveyor chain

PIV Gear Units



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For reliable and accurate variable  speed control in a wide field of applications the Stone-Platt range of fully metricated Positive Infinitely Variable (PIV) gear units is second to none. The basic PIV units offer variable speed ratios up to 6:1, output speeds up to 3550 r.p.m. and an intput power range from 0.75kW to 7.5kW (1 to 10hp).

Additional input and output gear modules give extremely low output speeds,with accuracy of speed holding within 0.01%, a wide speed range and high powers. With such a comprehensive range of PIV units and modules Stone-Platt Transmissions can solve most mechanical speed control problems.

This outlines the general capability of Stone-Platt Transmissions PIV Gear Units. More detailed technical information giving specific data (reduction ratios, output speed, dimensions, etc.) covering the range of units is contained in a series of Application Data Sheets, available on request.


The heart of the PIV unit is the all metal slatted chain and the grooved wheelfaces. The slats in the chain move laterally to engage the grooves in the wheelfaces. Therefore the chain cannot slip. The pitch diameter of both pairs of wheelfaces is controlled to an infinite number of positions by the pivoting control levers and the control screw.

Positive transmission of power
Outstanding stability of speed

Simplicity of design

Reliability of operation

High efficiency
Exceptional torque characteristics
Operationally reversible
All metal construction
Suitable for horizontal or vertical mounting
Dual drive shafts provide flexibility of coupling
Totally enclosed construction enables use in hostile environments

Maximum speed setting

The input shaft wheelfaces are close together, forming a large driving diameter. The output shaft wheelfaces are automatically separated to form a small driven diameter.

Continuous oil lubrication

Range of auxiliary gear modules extends field of application

The following range of accessories is available for use with all units:
Electronic remote control, remote hand control, fine adjustment control, lever control, bevel control, electrical speed indication.      

Minimum speed setting

The input shaft wheelfaces are far apart, forming a small driving diameter. The output shaft wheelfaces are automatically closed to form a large driven diameter.

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