Lull 1044C-54 Series II Service Manual - Manual (Page 84)

Supply, Pressure, and Return Hydraulics
5-2 31200079
These circuits are supplied by a two-section, gear-type hydraulic pump,
driven directly from the transmission power takeoff. The closest to the
shaft pump supplies flow to all circuits except steering and the steer
selector valve. The second pump supplies flow to all circuits via the
steering priority valve.
The boom extension and hoist circuits are controlled by a two-spool valve
with pressure relief. The frame tilt, carriage tilt, transfer carriage, and
auxiliary circuits are controlled by a four-spool valve (five-spool optional)
with pressure relief. The carriage tilt circuits are also equipped with two
work port relief valves. The outrigger circuits are controlled by two
additional valve sections with no-relief plugs. The steering circuit is
controlled by a steering control unit and steering mode selector valve. The
service brake circuit is controlled by a hydraulic power brake valve and
includes an accumulator.
The boom extension, boom hoist, carriage tilt, outrigger, and frame tilt
cylinders are equipped with externally mounted counterbalance valves.
The counterbalance valves prevent movement of the cylinders in event of
downstream hydraulic line failure, leakage through the main control valve
or fittings. The counterbalance valves prevent movement of the cylinders
when the engine is off, even if the control valve levers are operated. The
counterbalance valves also provide over-load relief protection.
The hydraulic reservoir is mounted on the right-hand side of the machine.
The hydraulic system return filter/magnetic separator is located at the top
of the reservoir. The strainer and suction line is located at the bottom of the
back side of the reservoir.