Manifold And Hydraulic Pumps; Hydraulic Brake Pressure Adjustment - Skyjack SJ61T Service Manual

Service and Maintenance

Manifold and Hydraulic Pumps

5.8-1 Hydraulic Brake Pressure
Adjustment
Maintaining accurate hydraulic brake pressure is im-
portant when it comes to safe aerial platform operation.
1. Ensure the aerial platform is on a firm level
surface and is in stowed position.
2. Locate the pressure gauge on the brake
valve assembly.
RV5
Pressure Relief Valve
V3
Brake Hand Pump
PR1
Pressure Reducing Valve
Brake Manifold
3. Remove the wiring from two valvesaxle
lockout valve wires 65 and 02, and two
speed valve wires 45A and 02. Mark the
valves to ensure you put the wiring back in
the correct positions later.
Failure to remove the wiring may cause
damage to components downstream.
4. Locate brake system pressure reducing
valve PR1. Loosen the lock nut and turn
the adjustment stem gently clockwise 2 full
turns.
Page 212
Pressure Gauge
V1
Release Override
CAUTION
December 2007
Section 5 - Procedures
CAUTION
Valve damage will occur if tightened
too much.
WARNING
Ensure that there are no personnel or
obstructions in test area and there is
sufficient room for forward or reverse
travel.
5. Start the engine from the platform control
console and extend the boom slightly to
achieve low speed drive.
6. Drive aerial platform forward or reverse. The
pressure gauge reading should be 550 psi.
Stop the aerial platform. Follow the next
steps for adjusting relief valve pressure
if needed. If no adjustment is required
continue to step 10.
7. Locate brake pressure relief valve RV5 and
loosen the lock nut.
8. Turn the adjusting stem on the pressure
relief valve RV5 ¼ of a revolution at a
time clockwise to increase pressure or
counterclockwise to decrease pressure.
Drive aerial platform forward or reverse, note
pressure and stop the aerial platform.
9. Repeat step 8 until brake pressure is
achieved (550 psi) then tighten lock nut on
brake system pressure relief valve RV5.
10. Locate brake system pressure reducing
valve PR1 and turn the valve gently
counterclockwise to the initial position.
11. Drive aerial platform forward or reverse.
Pressure gauge reading should be 500 psi.
12. Stop aerial platform and adjust pressure
reducing valve PR1 1/4 turn at a time by
turning either clockwise to increase pressure
or counterclockwise to decrease pressure.
13. Repeat step 11 and 12 until brake pressure
is achieved (500 psi) then tighten lock nut on
brake system pressure reducing valve PR1.
14. Reinstall the wiring in the same positions it
was removed from in step 4.
15. Test the brake and two speed functions.
Telescopic Boom Series
Models SJ61T & SJ66T
194312