The purpose of this manual is to provide Information necessary for the normal servicing of the Sundstrand Heavy Duty
(20-27 Series) family of hydrostatic transmissions. This Includes unit and component description, as well as function,
troubleshooting, control adjustments, and minor repair procedures. This servicing may be performed, following the
procedures in this manual without affecting the unit warranty.
A Sundstrand transmission does occasionally require servicing and your transmission has been designed with this in
mind. Many of the parts on the heavy duty transmissions are Interchangeable throughout the entire 20 Series family.
This includes such items as the controls, charge system and manifold components. In addition, many repairs or
adjustments can be accomplished without the necessity of removing the unit from the vehicle provided the unit is
accessible and can be thoroughly cleaned before beginning any procedures. Since dirt or contamination is the greatest
enemy of any type of hydraulics, the greatest possible cleanliness is desirable.
Sundstrand Hydro-Transmission provides a complete repair service for its products. The specifics of this service are
included in Sundstrand Bulletin 9614.
The torque values, pressure settings and dimensions used throughout this manual are given in English measurements. A
metric conversion chart for all pressures and torque values is provided at the back of the manual.
© Copyright 1980, SUNDSTRAND CORPORATION.
All rights reserved. Contents subject to change. Information contained herein should be confirmed before placing order.