Table 4-1. Hydraulic Pressures.

pressure indicated on the gage. Place the selector

lever in the reverse position and repeat the

procedure. Note the pressure indicated on the gage.

(c) If the pressures indicated are above 65

psi, and do not exceed normal pump pressure noted

in (1) above, the pressure in the clutch circuit is

normal.

(d) If the pressure is below 65 psi, check for

low oil level. restricted lines or passages, damaged

seal rings, defective or incorrectly adjusted selector

valve, defective pump. or excessive leaks in the disc

and drum assembly.

(e) When the engine is idling. and either

clutch is engaged. the clutch circuit pressure should

be 15 to 25 psi.

(4) Check the forward and reverse clutch

pressures with the wheels free running.

(a) Install pressure gages, calibrated to 300

psi, in the pump pressure port and the converter

pressure port (fig. 4-9) and clutch pressure port

(fig. 4-10).

(b) Raise the truck so that both drive

ME 3930-624-34/4-10

wheels are off the floor. Block the truck securely

Figure 4-10. Checking clutch pressure.

with both wheels free to rotate. Secure the inching

pedal up so the inching valve plunger cannot move.

(b) Start the engine and position the truck

Bring oil temperature to 200F.

against the wall. Apply both the parking brake and

(c) Run the engine at full governed speed

the foot brake-the drive wheels must be locked.

and check the pressures with the selector lever in

With the truck in this stalled condition, place the

both forward and reverse positions. The following

selector lever in the forward position and accelerate

cable indicates the normal pressures (in psi) at the

the engine momentarily to wide open throttle. DO

specified engine speeds:

not allow engine rpm to exceed 1500 rpm. Note the

Table 4-1. Hydraulic Pressures.

Forward

Reverse

Main line

Engine

clutch

Converter

(pump press)

rpm

Minimum Maximum Minimum Maximum

Minimum Maximum

500

100

2000

125

105

Increase the pressure, if necessary. by adding a

(d) At a speed of 2000 rpm, release the

spacer between the spring and the hex head plug on

inching pedal. Clutch pressure should drop to zero

the lower right of the adapter. Cut off a small

in both forward and reverse positions.

portion of the spring (or remove washers. if any) to

(e) Disconnect the cooler return hose at the

return port on the left side of the adapter. Plug the

reduce pressure.

f. Regulating Valve Adjustment.

port. Install a 200 psi pressure gage in the hose.

With the clutch engaged and the oil sump tem-

(1) Remove the floor plate.

(2) Install a 0 to 160 psi pressure gage at the

perature at 120 to 170F, run the engine at

governed speed. The relief valve which protects the

pressure part on the top right of the control cover.

Refer to figure 4-11.

cooling oiI circuit must open at 65 psi to 100 psi. It

should open near 100 psi, and never under 6.5 psi,

4-8