Manitowoc Grove RT770E, Service Maintenance Manual

Page: 65 / 357

2-25
GROVE
RT770E HYDRAULIC SYSTEM
2
Published 11/26/2014, Control # 447-05
5. Disconnect and cap the hose running from the main
directional control valve to the hoist(s) port “A” on the
hoist motor control valve. Disconnect the hoist brake
release line at the hoist Figure 2-6. Cap fitting and plug
hose.
6. With the boost switch on, attempt to hoist up with the
engine running at full RPM. Adjust the main directional
control valve hoist “B” port relief to 241 bar ±4 (3500 psi
±50).
7. With the boost switch on, attempt to hoist down with the
engine running at full RPM. Adjust the main directional
control valve hoist “A” port relief to 241 bar ±4 (3500 psi
±50).
8. If auxiliary hoist is installed, repeat 5, 6 and 7 for the
auxiliary hoist.
9. Reconnect hose to port “A” of the hoist motor control
valve and reconnect hoist brake release line on the
hoist.
10. Completely retract lift cylinder. Attempt to lift down with
the engine running at full RPM. Gauge should read
2000 psi +700/-0 (138 bar +48/-0). This relief valve is
non-adjustable.
11. Completely retract the boom; attempt to telescope in
with engine running at full RPM. Adjust the main
directional control valve to telescope “B” port relief to
241 bar ±4 (3500 psi ±50).
12. Completely extend boom; attempt to telescope out with
engine running at full RPM. Adjust the main directional
control valve telescope “A” port relief to 186 bar ±4
(2700 psi ±50).
13. Remove pressure gauge from the load sense test port.
Procedure B - Main Directional Control Valve
Pilot Supply Pressure
1. Install pressure check diagnostic quick disconnect with
gauge onto test nipple at pilot supply test port
Figure 2-7.
2. Disconnect the hoist brake release line at the main hoist
Figure 2-6. Cap fitting and plug hose.
3. While attempting to hoist down with the engine running
at full RPM, check the pilot supply pressure.
4. Adjust the pressure reducing cartridge located in the
inlet of the hoist/lift/telescope directional control valve to
22 to 31 bar (325 to 450 psi). Turn adjustment clockwise
to increase or counterclockwise to decrease the
pressure setting.
5. Remove pressure gauge from the pilot supply test port.
6. Reconnect the hoist brake release line on the hoist.
Procedure C - Swing Brake Pilot Supply
Pressure
1. Install pressure check diagnostic quick disconnect with
gauge onto test nipple at swing brake pilot supply valve
test port Figure 2-8.
2. Adjust pressure reducing valve cartridge to 17 bar +4/-0
(250 psi +50/-0 psi).
3. Remove pressure gauge from the test port.
Procedure D - Brake Charge Supply Valve
Relief Pressure
1. With engine off, disconnect hose at port “CF1” at the
brake charge/CAC fan motor supply valve Figure 2-9;
cap and plug all openings.
2. Install pressure check diagnostic quick disconnect with
gauge onto test nipple at brake charge/CAC fan motor
supply valve test port.
3. Start engine and operate at full RPM. Adjust “Inlet Relief
Valve” to 204 bar +4/-0 (3000 psi +50/-0).
4. Remove pressure gauge from test port, and reconnect
hose to port “CF1”.
FIGURE 2-8
Gauge
Port
Pressure Reducing Valve
7540-2