Manitowoc Grove RT770E, Service Maintenance Manual

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HYDRAULIC SYSTEM RT770E
2-10 Published 11/26/2014, Control # 447-05
Pump Distribution
No. 1 Pump
The torque converter drives the No. 1 pump.
Section one of the No. 1 hydraulic pump supplies the hoist,
lift, and telescope directional control valve. The valve
sections control the following functions: main hoist, boom lift,
boom telescope, and, when equipped, auxiliary hoist.
Hydraulic oil flowing from this valve bank returns to the
reservoir filter.
Section one also supplies the swing brake and armrest
lockout manifold. The manifold contains the swing brake
release valve and the controller armrest lockout valve.
Hydraulic oil flowing through the manifold supplies the swing
power brake valve, and the hoist, swing, telescope, and lift
hydraulic remote control valves.
Section two of the No. 1 hydraulic pump supplies the rear
axle oscillation lockout valve and the integrated outrigger/
rear steer valve.
Output from pump number 1, section 2 passes through a
priority flow control valve for the hydraulic oil cooler motor
and the high speed boost selector valve. When the boost
valve is de-energized, the oil flows to the normal delivery.
When the valve is energized, the oil is combined with the
output of pump number 1, section 1 to provide additional oil
capacity to the section 1 functions.
No. 2 Pump
The engine drives the No. 2 pump.
The No. 2 hydraulic pump supplies the front steer/swing
directional control valve. A load sense flow divider located in
the swing directional control valve ensures the front steer
valve gets priority flow upon demand and the swing
directional control valve gets any excess flow.
No. 3 Pump
The torque converter drives the No. 3 pump.
The No. 3 hydraulic pump supplies the service brake dual
accumulator charge valve and the charge air cooler fan
motor. The pump delivers its flow via a 15.1 L/min (4.0 gpm)
priority flow divider to the dual accumulator charge valve;
excess flow passes through a 17.0 L/min (4.5 gpm) priority
flow divider and on to the charge air cooler fan motor.
Troubleshooting
Symptoms and Solutions
6 Temperature Switch- Low Fan Speed
7 Temperature Switch-High Fan Speed
8 Hydraulic Tank
9 Oil Level Gauge
10 Step
Item Description
Symptom Probable Cause Solution
1. No hydraulic oil
flows in systems. a. Low hydraulic oil level. a. Check system for leaks. Make repairs
as needed. Fill reservoir.
b. Reservoir-to-pump suction lines
broken or restricted. Air entering at
suction lines. Pump not priming. b. Clean, repair, or replace lines as
necessary. Check lines for security,
absence of cracks, and proper
attachment. Tighten, repair, or
replace parts as necessary.
c. Pump shaft sheared or disengaged. c. If drive shaft is damaged or sheared,
remove and repair or replace as
necessary
d. Internal contamination. d. Drain, flush with recommended oil
mixture, then drain and refill system
with recommended hydraulic oil.