42–10 Foot Brake Valve
Actuator Lubricating,
Bendix E–6
1.
Remove the brake valve. For instructions, see
Group 42 of the
School Bus Chassis Workshop
Manual
.
2.
From the outside of the cab, pull the valve away
from the frontwall and remove the brake plunger.
3.
Wipe off the old grease from the plunger and the
adaptor.
4.
Inspect the bore of the adaptor and the sliding
surface of the plunger. While some discoloration
is permissible, there should be no pitting or
roughness to the adaptor bore or the sliding sur-
face of the plunger. If pitting or roughness exists,
replace damaged parts with new ones.
5.
Lubricate the adaptor bore and the sliding sur-
face of the plunger with an approved silicone-
based grease, Dow Corning 55 O-Ring Lubricant
(formerly Molykote DC–55M), or Loctite
®
V–755
O-Ring Lubricant.
6.
Using a new gasket, install the plunger and
brake valve following the instructions in Group
42 of the
School Bus Chassis Workshop Manual
.
42–11 Relay Valve Checking,
Midland
Chock the tires. Start the engine and run it long
enough to pressurize the air system to at least 80 psi
(550 kPa), then shut down the engine.
Repeat as necessary to maintain 80 psi (550 kPa)
pressure during this check.
Clean off road grime from the relay valve, and any
debris from the valve exhaust port. Listen for air
leakage around the fittings or exhaust port. Tighten
the fittings as necessary. Use two wrenches to avoid
twisting the tubing.
If the valve fails this check, or is damaged, repair or
replace it; see the
Midland Service Manual
for in-
structions. Remove the chocks from the tires.
42–12 Front Air Brake Hose
Inspecting
1.
Park the vehicle on a level surface. Shut down
the engine, set the parking brake, and chock the
rear tires. Open the hood.
2.
Start the engine. Run it at idle until the air pres-
sure gauges read at least 90 psi (620 kPa).
3.
Shut down the engine.
4.
Fully depress the brake pedal. Hold it down.
5.
Without releasing the brake pedal, listen for a
steady hissing from the front brake hoses.
6.
If no hissing is heard, the hoses do not leak.
7.
Start the engine.
WARNING
The next step requires an assistant. Use caution
when working near the front wheels as they are
turned from side to side. Failure to use caution
could result in injury to the assistant.
8.
While the assistant observes the hoses, turn the
wheels to full-lock, to one side and then the
other.
f420011a
05/28/93
1
2
3
A
A. Grease exit.
1.
Brake Chamber
2.
Slack Adjuster
3.
Grease Fitting
Fig. 5, Camshaft Bracket Bushing Lubrication
Brakes
42
School Bus Chassis Maintenance Manual, March 2003
42/5
