Brake Coolant Pump Assembly

TM 9-2520-249-34&P

(2) Should the filter element become

pressure to the hydraulic system only when the vehicle

clogged, or if inlet oil pressure exceeds outlet oil

is moving forward. In neutral, or during any reversing of

pressure by 50 to 62 psi, the bypass valve will open.

the right track, no oil pressure is supplied.

This will permit the oil to bypass the filter element and

(2) This pump is the sole source of

flow directly through a passage in the cover housing to

hydraulic pressure at the beginning of tow- or push-

the outlet port.

starts. When the vehicle is moving forward, the pump

assists the input driven pump in supplying oil to the

hydraulic system.

2-21.

Main-Pressure and Lockup Regulator Valve

Body Assemblies

2-19.

Brake Coolant Pump Assembly

a. Description (FO-10).

a. Description.

(1) The main-pressure regulator valve

(1) A dual-section brake coolant pump

body assembly (34) includes three valve groups. These

assembly (40, FO-11) is located directly below the drive

are as follows-(2), (3) and (4) below.

bevel gears and inside of sump cover (76). Two pairs of

(2) The main-pressure regulator group

gears (48 and 51) are installed in body assembly (44).

consists of items (35) through (40).

Cover assembly (55) has two intake ports each of which

(3) Flow valve (46) is alone in its bore.

contains a check valve arrangement and a screen

(4) The lockup shift valve group consists

assembly (65). Cover assembly (55) is bolted to the

of items (43) through (48).

open end of body assembly (44).

(5) These three valve groups move

(2) Gears (42) are splined to the shaft

lengthwise in bores of valve body (41).

ends of gears (48) and retained by nuts (41). Gears (42)

(6) Lockup regulator valve body assembly

engage the straight-cut teeth of pump drive gear (42,

(20) includes items (21) through (29).

FO-5). The bevel teeth of pump drive gear (42) are

b. Main-Pressure Regulator Valve Operation

engaged with bevel driven gear and shaft (43). The

(FO-10). Main pressure is exerted against the right end

pump drive gear and shaft is supported by a needle

of valve (40), pushing it against springs (38) and (39).

bearing (47, FO-11) pressed in the center of pump body

When spring force balances hydraulic pressure, main

assembly (44). Two outlet ports in the body -assembly

pressure is regulated.

index with passages in the bevel gear housing.

c. Lockup Shift Valve Operation(FO-10).

b. Operation. The pump operates when the

Lockup shift valve (43) located in the right bore, is

vehicle is moving. When the brakes are applied, the

actuated by pitot pressure working against forces of

pump draws oil from the sump and directs it to the brake

spring (45) and throttle pressure. The lockup clutch

disks for coolant. When the brakes are released the

circuit and the converter-in circuit are controlled by the

pump draws air. During steer, the pump supplies

lockup shift valve. When the spring is depressed, the

coolant to the reverse or steer clutches. Refer to

lockup clutch is applied, and when the valve is seated,

paragraph 2-13b(4), for air valve operation.

the lockup clutch is exhausted. The valve permits a

greater flow of oil to the converter while the lockup

clutch is released.

2-20.

Oil Filter Assembly

d. Flow Value Operation (FO-10). Flow valve

a. Description (FO-10). Oil filter assembly (4)

(46) is located in the left bore and is actuated entirely by

is located in oil filter housing assembly (6) which is

oil pressures. The flow valve is interconnected with the

mounted with four bolts (13) on the right side of the

lockup shift valve and the manual-operated control

converter housing. Oil filter assembly (4) includes a

valve body. When any manual shift is made (except to

replaceable, cleanable filter elements (5.1) having

neutral), a pressure differential causes the flow valve to

outside-in flow characteristics. The element is screen

move rearward. This interrupts the lockup clutch circuit

type, 80x80 mesh. A bypass valve is located within the

and causes it to exhaust. When the shift is completed,

cover housing above the filter element.

equalizing pressure (through the lockup regulator valve

b. Function (FO-10).

in later models) returns the valve to its forward position

(1) Oil pumped by the input pressure

and the lockup circuit is restored. Thus, the flow valve

pump (and output driven pump when the vehicle is

causes release of the lockup clutch while shifts are

moving forward) enters through a passage in the bottom

being made.

of filter housing (8) and surrounds filter element (5.1).

e. Lockup Regulator Valve Operation (FO-10).

Pressure differential causes the oil to flow through the

(1) The lockup regulator valve is

screen to a passage in the cover housing. This passage

connected between the lockup shift valve and the flow

indexes with the outlet port at the top of filter housing (8)

valve.

where it enters the hydraulic system.

2-8