262
229042ABA SJ46 AJ+, SJ46 AJ, SJ51 AJ
Section 5 – Procedures Manifold and Hydraulic Pumps
5.9 Manifold and Hydraulic
Pumps
5.9-1 Hydraulic Brake Pressure
Adjustment
Maintaining accurate hydraulic brake pressure is
important when it comes to safe MEWP operation.
1. Ensure the MEWP is on a firm level surface and
is in the stowed position.
2. Locate the pressure gauge on the brake valve
assembly.
2
3
1
3. Connect a pressure gauge (69 bar / 1000 psi) to
port BR
1
.
4. Remove the wiring from three valves: differential
lock valve wire numbers 165 and 02, axle
lockout valve wires 65 and 02, as well as two
speed valve wires 45A and 02. Mark the valves
to ensure you put the wiring back in the correct
positions later.
CAUTION
Failure to remove the wiring may cause damage to
components downstream.
5. Locate brake system pressure reducing valve
PR1
2
. Loosen the lock nut and turn the
adjustment stem gently clockwise 2 full turns.
WARNING
Valve damage will occur if tightened too much.
WARNING
Ensure there are no personnel or obstructions in
test area and there is sufficient room for forward or
reverse travel.
6. Start the engine from the platform control
console and extend the boom slightly to achieve
low speed drive.
7. Drive the MEWP forward or reverse. The
pressure gauge reading should be 38 bar (550
psi). Stop the MEWP. Follow the next steps for
adjusting the relief valve pressure, if needed. If
no adjustment is required continue to step 10.
8. Locate brake pressure relief valve RV4
3
and
loosen the lock nut.
9. Turn the adjusting stem on the pressure
relief valve RV4 one-quarter of a revolution
at a time clockwise to increase pressure, or
counterclockwise to decrease pressure. Drive
the MEWP forward or reverse, note the pressure,
and stop the MEWP.
10. Repeat step 9 until brake pressure is achieved
(38 bar / 550 psi) then tighten the lock nut on
brake system pressure relief valve RV4
3
.
11. Locate brake system pressure reducing
valve PR1
2
and turn the valve gently
counterclockwise to the initial position.
12. Drive the MEWP forward or reverse. The
pressure gauge reading should be 34.5 bar (500
psi).
13. Stop the MEWP and adjust pressure reducing
valve PR1
2
one-quarter of a turn at a time
by turning either clockwise to increase the
pressure, or counterclockwise to decrease the
pressure.
14. Repeat step 11 and 12 until the brake pressure
is achieved 34.5 bar (500 psi), then tighten the
lock nut on brake system pressure reducing
valve PR1
2
.
15. Reinstall the wiring in the same position it was
removed from in step 4.
16. Test the brake and two-speed functions.
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