TM 5-3805-298-23-1
0004
IMPLEMENT HYDRAULIC SYSTEM CONTINUED
A ball valve for lowering the loader arms is located inside the front frame. Use the ball valve when the engine will
not start and the lift arms are raised. Oil from the head end of the lift cylinders will flow through the ball valve to the
tank.
Quick Coupler System
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The quick coupler system provides a means to quickly connect and disconnect work tools from the machine. Using
the quick coupler switch on the right hand console in the cab. The quick coupler switch activates the quick coupler
solenoid to extend or retract the quick coupler pins. When the quick coupler switch is moved to the engaged posi-
tion, the quick coupler cylinder extends pushing the coupler pins outward. When the quick coupler switch is moved
to the disengaged position, the quick coupler cylinder retracts pulling the coupler pins inward.
The quick coupler system is equipped with a manual release valve located on the quick coupler check valve. Turn
the knob on the manual release valve counterclockwise to open the valve and relieve pressure. Manually push the
quick coupler pins in to disengage the work tool from the machine.
Ride Control System
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The ride control system acts as a shock absorber for the bucket. It reduces the pitching motion of the bucket, while
driving over rough terrain. The system uses four nitrogen charged accumulators, two with a higher precharge and
two with a lower precharge. The accumulators have an internal cylinder that is charged with nitrogen. The nitrogen
charged piston acts as a shock absorber resisting or dampening the hydraulic flow. When the ride control switch is
turned ON, the load acts against the head end of the lift cylinders. Hydraulic oil from the head end of the lift cylin-
ders will try to flow into the accumulators. When the bucket is empty, the system will direct hydraulic oil into the
lower precharge accumulators. When the bucket is loaded, the system will also direct hydraulic oil into the higher
precharge accumulators. All four accumulators are used with a loaded bucket due to the higher pitching motion
working against the head end of the lift cylinders.
BRAKING AND HYDRAULIC FAN SYSTEM
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Braking System
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The braking and hydraulic fan system utilizes a fixed displacement hydraulic pump. The braking system has priority
over the hydraulic fan system. When the engine is started, hydraulic oil is drawn from the hydraulic tank by the
brake and fan drive pump. Hydraulic oil flows from the brake and fan drive pump to the priority valve.
Hydraulic oil flows through the priority valve to the brake accumulator charging valve. When the two brake
accumulators are charged, the priority valve directs most hydraulic flow to the hydraulic fan. If brake pressure
drops, the system will redirect hydraulic oil back to the two brake accumulators in order to maintain pressure.
The flow of hydraulic oil from the brake accumulators is blocked by the brake control valve. When the brake pedal
is pressed, the brake control valve routes hydraulic oil to the service brakes engaging the service brakes. Pressure
feedback is sensed by the brake control valve allowing the operator to feel the application of the service brakes.
Hydraulic Fan System
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The speed of the hydraulic fan is limited by a flow control valve. The flow control valve is controlled by the demand
fan solenoid valve which is controlled by the transmission ECM. The transmission ECM varies flow through the
flow control valve to raise or lower the hydraulic fan speed. The transmission ECM sets fan speed based on the fol-
lowing inputs:
Inlet manifold temperature
Transmission oil temperature
Hydraulic oil temperature
Engine coolant temperature
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