HYDRAULIC AND AIR SYSTEMS 2250 SERVICE/MAINTENANCE MANUAL
2-20
Published 07-19-16, Control # 249-01
9. Stop the engine.
10. Remove the gauges and install protective caps over the
adjusting screws and gauge couplers.
11. If the crane has the cold weather option, connect the
electric plug to the fan bypass valve.
Checking the Charge Pressure
Check the charge pressure for the load drums, boom hoist,
luffing hoist, swing, and both travel pumps, one at a time, as
follows.
1. Stop the engine.
2. Connect an accurate 0 to 69 bar (0 to 1,000 psi)
hydraulic pressure gauge to the gauge coupler for the
desired pump (Figure 2-16
).
3. Start and run the engine at low idle.
4. Note and record the gauge reading. The gauge should
read 22,4 to 25,8 bar (325 to 375 psi).
NOTE: Charge pressure can be monitored on the
diagnostic screen for each function. The charge
pressure shown on the diagnostic screens can vary
±6,9 bar (100 psi) from that shown on the pressure
gauges.
5. If the proper pressure is not obtained, adjust the charge
pressure relief valve for the corresponding pump. See
the instructions in the pump manufacturer’s manual.
6. Stop the engine and remove the gauge from the coupler
(Figure 2-16
). Install a protective cap over the coupler.
Checking the Operating Pressure
It will be necessary to monitor the pressure and pump
command on the diagnostic screens of the digital display
during the following procedures. Do not confuse PUMP
COMMAND with HANDLE COMMAND on the display.
Boom Hoist Down
1. Stop the engine.
2. Loosen the lock nut on the adjusting screw at the down
multifunction valve in the boom hoist pump.
3. Turn the adjusting screw out until it stops. Then turn the
adjusting screw in 1-3/4 turns.
4. Start and run the engine at 1,500 rpm and operate the
boom hoist in the down direction (no wire rope or load on
the drums). The drum should turn freely. If not, proceed
as follows.
a. Stop the boom hoist drum.
b. Turn the down adjusting screw in 1/4 turn.
c. Repeat step 4
through step 4b until the drum turns
freely.
5. Hold the adjusting screw and securely tighten the lock
nut.
Boom Hoist Up
1. Stop the engine.
2. Disconnect the electric plug from the boom hoist brake
solenoid valve (Figure 2-24
). This will stall the boom
hoist pump.
NOTE: If equipped with a luffing hoist, disconnect the
electric plug from the luffing hoist brake solenoid
valve (Figure 2-25
).
3. Start and run the engine at 1,500 rpm.
CAUTION
Overheating Damage!
Avoid equipment damage due to overheating system
components.
Do not hold any function on stall for more than 10
seconds.
FIGURE 2-24
Electric
Plug
P924
Boom Hoist Brake Solenoid Valve
Access at Left Rear Inboard Side of Rotating Bed
FIGURE 2-25
Access Through Center Hole in Rotating Bed
P973
Electric
Plug
(typical)
Swing Brake
Solenoid Valve
Travel Brake
Solenoid Valve
Luffing Hoist Brake
Solenoid Valve
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