Chapter 7. REPAIR OF TRANSMISSION

CHAPTER 7

REPAIR OF TRANSMISSION

7-3.Operation

7-1. General

a. Oil is directed from the oil pump to the regulating

The transmission is a constant mesh countershaft

transmission, coupled to the engine crankshaft by a

valve (fig. 7-1) which regulates main pressure and

torque converter, and driving the power axle by a pinion

bypasses excess oil to the lube circuit. Oil under main

gear on its output shaft. Details of design and operation

pressure then flows to the inching valve, which is

are described in the following paragraphs.

controlled through linkage from the brake pedal.

Depressing the brake pedal allows the inching control

valve to move outward, gradually blocking main

7-2.Description

pressure feed to a dump valve located in the main valve

a. The transmission uses self-adjusting, corkfaced

body next to the inching valve. The end of the dump

clutch disks for forward-reverse shifting. Ball and roller

valve is also fed from an orifice directly by main

bearings are used throughout. All gearing is precision

pressure which positions the dump valve so that oil from

straight spur design. The control valve is integral in this

the inching valve can flow through it to the selector

compact, self-contained unit, as is the input pump.

valve.

b. The hydraulic clutches are contained in one

b. Converter oil flow comes directly from the oil pump

balanced assembly. The plates drive concentric shafts.

outlet but is reduced in pressure by a restriction through

The outer shaft drives a gear which is in direct mesh

which oil must pass to get into the converter. Exit oil

with the output gear on the output shaft. This transmits

from the converter goes to a bypass valve located in the

forward rotation to the output shaft. The inner shaft

converter oil out line. This bypass valve directs oil to

drives a gear which is in mesh with the output gear

the sump in case of a clogged oil cooler or clogged

through an idler gear. This transmits reverse rotation to

cooler lines and provides a safety feature against

the output shaft.

extreme internal converter pressure caused by

c. The main case is of three piece cast construction.

accidental restrictions. Oil from the cooler is directed to

The rear half contains a heavy diaphragm midwall which

the lube circuit which delivers cooled oil under pressure

forms one side of a rigid straddle mounted support for

to the clutch plates and bearings.

the output gear and shaft. Oil passages run within the

c. Suction oil flows through the filter screen before

walls of the case. There are no external lines except

entering the oil pump.

those to the cooler.

d. Power flow through the transmission is illustrated in

figure 7-2.

7-1