42–01 Air Dryer Inspecting,
Bendix AD–9
1. Check the reservoirs for moisture. A small
amount (teaspoon or less) is normal. Larger
amounts may mean that the desiccant needs to
be replaced. Check the mounting and connecting
lines.
2. Tighten the fasteners attaching the air dryer to
the vehicle. Use the following torque values.
28 lbf·ft (38 N·m) for SAE grade 5, 3/8–16 fas-
teners.
135 lbf·ft (183 N·m) for SAE grade 5, 5/8–11 fas-
teners.
Check all air lines, fittings, and electrical connec-
tions for damage, leakage, or looseness.
3. Replace damaged or leaking parts, and tighten
loose fittings or electrical connections.
42–02 Air Brake Valve
Inspecting and Leak
Checking, Bendix BP–R1
1. Clean the valve exterior and inspect it for corro-
sion and damage.
2. Inspect the air lines connected to the valve for
signs of wear or damage. Replace the lines as
needed.
3. Check the valve for leakage.
3.1 Apply the service brakes and hold them
on full line pressure of at least 80 psi
(550 kPa).
3.2 Check the air line fittings for leaks; tighten
or replace the fittings as needed.
3.3 Coat the exhaust port and body of the
valve with soapy water, and check for
leakage. Leakage is excessive if it pro-
duces a 1-inch (25-mm) bubble within 5
seconds.
If the brake valve does not function as
described above, or if leakage is exces-
sive, replace it with a new or remanufac-
tured unit. Repeat the leakage checks
before placing the brake valve in service.
42–03 Foot Brake Valve
Actuator Lubricating,
Bendix E–12
1. Clean any dirt, gravel, and other foreign debris
from the plunger boot and brake base bracket.
2. Check the brake plunger boot for cracks, holes,
or deterioration. Replace if necessary.
3. Lift up the edge of the brake plunger boot and
check the plunger for existing lubrication. If the
plunger is dry, remove it by removing the cotter
pin from the clevis pin and pulling the clevis pin
out. Remove the piston rod and boot. Lift out the
plunger. Lubricate the plunger and the tip of the
piston rod with barium grease part number BW
246671, or Penzoil Adhezoplex EP 2. Install the
piston rod, boot, clevis pin, and cotter pin.
If the plunger has grease on it, lift the edge of
the brake plunger boot enough to apply 2 to 4
drops of light oil around the brake plunger. Do
not over-oil. Install the plunger boot.
4. Lubricate the clevis pin with light oil.
5. Check for leakage; see Group 42 of the
Busi-
ness Class
®
Trucks Service Manual
for instruc-
tions.
42–04 Air Brake Valve
Operation Checking,
Bendix BP–R1 and E–12
Check for proper operation; see Group 42 of the
Business Class
®
Trucks Service Manual
.
42–05 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 turn off the engine.
Repeat as necessary, to maintain 80 psi (550 kPa)
pressure during this check.
Brakes 42
Business Class Trucks Maintenance Manual, October 1998 42/1
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