Manitowoc National Crane NBT40 Series, Service Manual

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2
NBT40 SERVICE MANUAL HYDRAULIC SYSTEM
National Crane
Published 8-01-2017 Control # 287-11
2-13
System Pressure Check
Insert a T-connector with a pressure gauge in the hydraulic
line at swivel port #3. This can be used to adjust the crane
system hydraulic pressure.
Hoist
NOTE: The hoist hydraulic circuit relief is set by two relief
valves on the main control valve.
1. Disconnect the two work port hoses (1, Figure 2-5) at
the hoist motor and cap the hoist motor ports.
2. Plug the hoses.
3. Start the engine and set the throttle to governed rpm.
4. Try to hoist up or down. Adjust relief valves on the main
control valve (Figure 2-2 &
Figure 2-3) to 26200
±689 kPa (4300 ±100 psi).
5. Shut down the engine.
6. Reconnect the hoses to the hoist.
Boom Lift
1. Start the engine and set the throttle to governed rpm.
2. Boom down until the boom bottoms out.
3. Set the boom down relief valve on the main control valve
(Figure 2-2 &
Figure 2-3) to 6894 ±689 kPa (1000 ±100
psi).
4. Boom up until the boom stops or stop the engine,
disconnect and cap the boom up hydraulic line.
5. Set the boom up relief valve on the main control valve
(Figure 2-2 &
Figure 2-3) to 24821 ±689 kPa (3600 ±100
psi)
6. Shutdown the engine.
7. Reconnect the boom up hydraulic line to the lift cylinder.
Telescope In and Telescope Out Reliefs
1. Remove the extend and retract (work port) hoses (1,
Figure 2-6) from the telescope cylinder. Cap the
telescope ports on the cylinder and plug the hoses.
2. Start the engine and set the throttle to governed rpm.
3. Push the telescope control lever to extend.
4. Adjust the telescope extend relief valve on the main
control valve (Figure 2-2 &
Figure 2-3) to 19994.8
±689 kPa (2900 ±100 psi).
5. Pull the telescope control lever to retract.
6. Adjust the telescope retract relief valve on the main
control valve (Figure 2-2 &
Figure 2-3) to 15513
±689 kPa (2250 ±100 psi).
7. Shut down the engine.
8. Reconnect the telescope cylinder hoses.
Outriggers
1. Select an outrigger (1, Figure 2-7) and remove one the
hydraulic lines shown in Figure 2-7.
2. Install a tee connector with a pressure gauge in the
disconnected line.
FIGURE 2-5
1
7580-2
FIGURE 2-6
7587-5
1
1
Reference Only