The transmission and hydraulic torque portion of the power train enacts an important role in transmitting engine power to
the driving wheels. In order to properly maintain and service these units it is important to first understand their function
and how they operate.
The transmission and torque converter function together and operate through a common hydraulic system.
necessary to consider both units in the study of their function and operation.
To supplement the text below, and for reference use therewith, the following illustrations are provided:
Basic Design Silhouette
Converter and Transmission Case Group
Three Speed Case and Clutch Group
Regulating Valve, Charging Pump and Filter Group
Axle Disconnect and Mechanical Parking Brake
Typical 28000 Cross Section
External Plumbing Diagram
Typical Three-Speed Power Flow
Clutch and Gear Arrangement
Ring Gear Installation
Shielded Bearing Installation
The R, HR, and MHR Model Transmissions are of three basic designs.
The R Model consists of a separate torque converter, mounted to the engine with the powershift transmission remotely
mounted and connected to the torque converter with a drive shaft.
The HR Model consists of a torque converter and powershifted transmission in one package mounted directly to the
The MHR version Is a mid-mount torque converter and transmission assembly connected to the engine by means of a
drive shaft. (See Fig. A for basic design silhouette.)
The shift control valve assembly may be mounted directly on the side of the converter housing or front transmission
cover, or remote mounted and connected to the transmission by means of flexible hoses. The function of the control
valve assembly is to direct oil under pressure to the desired directional and speed clutch. A provision is made on certain
models to neutralize the transmission when the brakes are applied. This is accomplished through use of a brake
actuated shutoff valve. The speed and direction clutch assemblies are mounted inside the transmission case and are
connected to the output shaft of the converter either by direct gearing or drive shaft. The purpose of the speed or
directional clutches is to direct the power flow through the gear train to provide the desired speed range and direction.
An axle disconnect is optional and is located on the output shaft. The drive to the front or rear axle can be disconnected
or connected by manual shifting.