Operation and maintenance manual

Section 250-0000
SM 2155 Rev 1 10-03
3
braking system for proper operation.
Pressure Test Points
Two diagnostic pressure test points, located in the
manifold at the rear left hand side of the tractor frame,
provide a quick and easy method of checking front and
rear brake system pressure. The pressure is taken
from the 'B1' (front) and 'B2' (rear) brake circuits.
CHECKING SYSTEM PRESSURE
WARNINGS
To prevent personal injury and property
damage, be sure wheel blocks and blocking
materials are properly secured and of adequate
capacity to do the job safely.
Hydraulic fluid pressure will remain
within the system after engine shut down.
Operate the treadle pedal continuously until the
pressure has dissipated before carrying out any
work on the braking system or serious injury
could result.
1. Position the vehicle in a level work area, apply the
parking brake, switch off the engine and turn steering
wheel in both directions several times to relieve any
pressure in the steering circuit.
2. Operate the treadle valve continuously to relieve
pressure in the braking system. Block all road wheels,
place the steering lock bar in the 'Locked' position and the
battery master switch in the 'Off' position.
3. Remove mounting hardware securing cover plate to
cradle assembly at the rear of the cab. Remove cover
plate to gain access to brake manifold valve.
4. Connect a hydraulic gauge, capable of recording a
pressure of 0 - 345 bar (0 - 5 000 lbf/in²), to remote
diagnostic pressure point on brake manifold valve.
5. Place the battery master switch in the 'On' position,
start the engine and monitor system pressure gauge.
Priority unloader valve pressure setting should be 170
bar (2 465 lbf/in²).
6. Pressure setting can be adjusted as described by
Section 250-0075, PRIORITY UNLOADER VALVE.
Note: Actuating pressure for the front and rear brake
circuits is 138 ± 6.9 bar (2 000 ± 100 lbf/in²) and can
be checked at remote diagnostic test points. Refer to
'Pressure Test Points'.
7. Shut off the engine and remove the pressure gauge
from brake manifold valve.
8. Secure cover plate to the cab wall with mounting
hardware.
9. Remove wheel blocks, place the steering lock bar in
the 'Stowed' position, start the engine and check the
'O' RING FACE SEALS (ORFS)
Where hydraulic lines are fitted with ORFS
connections, the following procedure should be
carried out during installation. Refer to Fig. 1.
a. Ensure 'O' ring/seal is in place and that joining
surfaces are clean. If necessary, retain 'O' ring/seal in
place with a light coating of grease or vaseline.
b. Initially, the nuts should be tightened by hand.
c. Where a hose is fitted, ensure that it is not twisted
or kinked when the nuts are tightened so that it is
allowed to adopt a natural position.
d. Where a tube is fitted, ensure that the connection is
aligned correctly.
e. Tighten the nut a further 1/4 to 1/2 a turn using the
correct size of spanner (wrench).
f. Check that a satisfactory hose or tube routing has
been achieved.
BLEEDING THE BRAKING SYSTEM
1. Fill hydraulic tank with oil specified in Section
300-0020, LUBRICATION SYSTEM. Fill brake coolant
tank with oil specified in Section 300-0020,
LUBRICATION SYSTEM. Switch on engine and
operate systems until correct operating pressures are
recorded.
Braking System - Braking System Schematic
SM - 1335
Fig. 1 - Assembly of Typical ORFS Connector
'O' RING
'O' RING
SLEEVE
TUBE
FITTING
NUT