Manitowoc Published 07-19-16, Control # 249-01 2-19
2250 SERVICE/MAINTENANCE MANUAL HYDRAULIC AND AIR SYSTEMS
9. On the diagnostic screens, check pump pressures for
the load drums, boom hoist, swing, and travel pumps.
a. Make sure the pressure reading for each pump is
13,8 to 34,5 bar (200 to 500 psi). Pump pressures
will be adjusted to their final settings later in this
procedure.
b. If pump pressures are not within the specified
range, stop the engine immediately. Determine the
cause of the faulty pressure and correct it.
10. Stop the engine.
11. Remove the bleed lines from the gauge couplers at each
pressure sender.
12. Perform the following procedures.
a. Engine throttle adjustment (MCC Electrician)—Do
not perform the remaining procedures until the
engine throttle is adjusted to the following proper
speeds:
- 950 to 1,000 rpm low idle
- 2,100 to 2,125 rpm high idle
b. Fan and pilot pressure adjustment
c. Charge pressure checks
13. With the engine at low idle, extend and retract all
cylinders (jacking, boom butt handling, gantry) three
times.
14. With the engine running at low idle, slowly cycle each
crane function in both directions for at least five minutes
to vent any remaining air from the hydraulic system.
15. Be sure all crane functions operate in the proper
direction in relation to control handle movement.
16. Check for hydraulic leaks, and correct the cause if
found.
17. Stop the engine and fill the hydraulic tank to the proper
level.
NOTE: MCC Assembly Personnel—Pressures and
speeds noted in the remaining procedures and any
adjustments you make to correct them must be
recorded in the appropriate Quality Verification
Form for the crane you are working on.
Calibrating the Controls
1. Calibrate the pressure transducers, if not already done.
2. Start and run the engine at high idle.
3. Depress and hold the swing holding brake switch (on the
swing handle) for one minute.
4. Repeat step 2
and step 3.
Adjusting the Fan and Pilot Pressure
See Figure 2-21 for the fan relief valve and components. See
Figure 2-23
for the pilot pressure relief valve and
components.
1. Stop the engine.
2. If the crane has the cold weather option, disconnect the
electric plug from the fan bypass valve before starting.
3. Connect accurate hydraulic pressure gauges to the
gauge couplers, as follows.
a. 0 to 345 bar (0 to 5,000 psi) at the fan relief valve
b. 0 to 69 bar (0 to 1,000 psi) at the pilot pressure relief
valve
4. Remove the adjusting screws from both valves. Then
reinstall them approximately 6 mm (1/4 in).
5. Start the engine.
6. With the engine running at low idle, turn the fan relief
valve adjusting screw in until the gauge reads
approximately 69 bar (1,000 psi).
7. With the engine running at high idle, turn the pilot
pressure relief valve adjusting screw in until the gauge
reads 22,4 to 25,8 bar (325 to 375 psi). Hold the
adjusting screw in position and securely tighten the lock
nut.
8. With the engine running at high idle, adjust the fan relief
valve, as follows.
a. Slowly turn the adjusting screw out to decrease the
pressure until the fans start to slow down and the
pressure starts to drop on the gauge.
b. Slowly turn the adjusting screw in. The fan speed
and pressure will increase.
c. Continue to slowly turn the adjusting screw in until
the pressure stops increasing. Then turn the
adjusting screw in an additional 1/2 turn.
The fan pressure should be 62 to 117 bar (900 to
1,700 psi).
If the pressure is okay, hold the adjusting screw in
position and securely tighten the lock nut.
If the pressure is not okay, determine the cause and
correct it.
CAUTION
Equipment Damage!
Inadequate oil pressure can damage hydraulic pumps.
Check the pump pressure during the first two minutes of
operation. If the pressure for any pump is not within the
specified range, shut down the engine immediately.
Troubleshoot to determine the cause of the problem.
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