BRAKE SYSTEM CD3340B/YB4411
9-12
Published 04/07/2015 Control # 569-00
BRAKE MODULATING VALVE REPAIR
Removal
1. Raise the crane by lowering the outriggers.
2. Shut off the engine and set the parking brake.
3. Shut off the accumulator needle valve. See Figure 9-7.
4. Press the foot brake pedal (brake modulating valve) as
many times as it takes to release any pressure
remaining in the brake system.
5. From underneath the operator’s cab, disconnect the
hydraulic hoses from the fittings. Plug the hoses to
inhibit contaminating the hydraulic system.
6. Remove the three capscrews and self-locking nuts
securing pedal mounting plate to the cab floor. Remove
the brake modulating valve and pedal assembly.
Disassembly
1. Remove the brake modulating valve from the pedal
assembly, by removing two capscrews (13, Figure 9-13).
2. Remove boot (1) from piston (2) and housing (12).
3. Remove piston (2), springs (3, 4 and 5), shims (6) and
retainer assembly (7) from housing (12).
NOTE: Observe and take note of the number of shims (6)
being removed from the housing.
4. Carefully remove cup (14) and seal (15) from housing
(12) bore. Be careful not to scratch or mar the bore.
5. Remove end plug (8) and spring (10) from housing (12).
Remove O-ring (9) from plug (8).
6. Carefully remove spool (11) from end plug (8) end of
housing (12).
NOTE: Be careful not to damage the spool or housing bore
as they are a matched set and not sold separately.
Assembly
A seal kit is available for repair of the valve. It consists of the
items indicated with a black dot in Figure 9-13.
NOTE: Lubricate all rubber components in repair kit with
clean hydraulic oil of the same type used in the
hydraulic system.
1. Clean all parts before assembling. Use a suitable
solvent.
2. Lubricate spool (11, Figure 9-13) with clean hydraulic oil
and carefully slide into plug end of housing (12).
NOTE: The spool must slide freely into the bore. If either
part is damaged, a new valve assembly may be
required.
3. Install new O-ring (9) on end plug (8).
4. Install spring (10) and end plug (8) into housing (12).
Tighten to a torque of 54.2-67.8 Nm (40-50 lb-ft).
5. Carefully install new cup (14) and new seal (15) into
bore of housing (12). Make sure they are installed in the
proper order and direction. Take care when installing not
to scratch or mar the housing bore.
6. Assemble springs (3, 4 and 5), shims (6) and retainer
assembly (7) into piston (2).
7. Carefully install piston (2) assembly into bore of housing
(12).
8. Install new boot (1) on housing (12) and piston (2).
9. Install the valve assembly onto the pedal assembly with
new capscrews (13). Tighten to a torque of 24.4-29.8
Nm (18-22 lb-ft).
10. After final assembly, the valve must develop a pressure
of 3792 ±345 kPa (550 ± 50 psi).
Installation
1. Place the brake modulating valve and pedal assembly in
location in the operator’s cab. Secure to the cab floor
with three capscrews and self-locking nuts.
2. Connect the three hydraulic hoses to the valve.
3. Open the accumulator needle valve and then start the
engine. Allow pressure to build in the brake system.
4. Bleed air from the brake system. See Figure 9-5.
WARNING
A raised and badly supported machine can fall on you
causing severe injury or death. Position the machine on a
firm, level surface before raising one end. Ensure that the
other end is securely chocked. Do not rely solely on the
machine’s hydraulics or jacks to support the machine
when working under it.
Disconnect the battery cables while you’re under the
machine to prevent the engine from being started.
Reference Only
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