GMC 4000 Series Service Manual page 460

idler lever and shaft assembly.
1. Install felt seal (5, fig. 5) and ball stud
(4) on the engine (1) or engine bracket (2).
2. Push the lever and shaft assembly onto
the engine mounted ball stud. Position nylon seat
(8), lock spring (9) and felt seal (5) on this outer
ball stud.
3. Guide the outer ball stud into the slot in
the frame bracket.
4. Install lock strap (10) and lock washer and
nut (11) on outer ball stud.
5. Connect relay rod and push rod to lever
and shaft assembly.
6. Adjust mechanical clutch linkage as de­
scribed previously in this section.
DESCRIPTION A N D OPERATION
The clutch hydraulic control system is typi­
cally and schematically illustrated in figure 6.
This system utilizes hydraulic pressure as a
means of transmitting clutch pedal movement
to the clutch release mechanism. The system
consists of a pedal-operated master cylinder and
a slave cylinder, interconnected with hydraulic
lines. Clutch pedal is connected to the master
cylinder push rod, and the slave cylinder push
rod is connected to the clutch release fork.
When clutch pedal is depressed, hydraulic
fluid is displaced from the master cylinder into
the slave cylinder, forcing the slave cylinder
piston outward. Movement of piston is trans­
mitted through slave cylinder push rod, and clutch
release fork to disengage the clutch.
G M C S E R V I C E M A N U A L
1 Engine
2 Engine Bracket
4 Ball Stud
5 Felt Seal
6 Nylon Ring
7 Lever & Shaft Assy.
shaft on models equipped with a mechanical clutch
linkage are given in " HYDRAULIC BRAKES"
(SEC. 5A).
HYDRAULIC TYPE CONTROLS
returns pedal to released (clutch engaged) posi­
tion. With pressure removed from hydraulic fluid,
clutch engages. Slave cylinder push rod return
spring forces push rod and piston rearward in
slave cylinder, displacing hydraulic fluid back
into the master cylinder. The above events occur
with each clutch disengagement.
periodically as stated below:
in master cylinder. Refer to LUBRICATION (SEC.
0) for recommended fluid and checking intervals.
At least once a year, drain and flush entire clutch
system and refill with new fluid.
for fluid leakage.
immediately.
_______________________ Page449
CLUTCH CONTROLS
ALL C O N V . M O D E L S EXCEPT " ES" M O D E L S
3 Lube Fitting
Figure 5 — Idler Lever and Shaft Assem bly
CLUTCH PEDAL A N D SHAFT
REPLACEMENT
Procedures for replacing clutch pedal and
When pedal is released, pedal return spring
The system should be checked and serviced
1. Maintain proper level of hydraulic fluid
2. Inspect entire clutch system
Leakage must be corrected
8 Nylon Seat
9 Lock Spring
10 Lock Strap
11 Lock Washer and
Nut
12 Frame Rail
T-3082-2
regularly