MAST HYDRAULIC SYSTEM
(Sheet 2 of 2)
LIFT CYLINDER. A ram type which moves up by hydraulic oil
High pressure mast hydraulic system consists of:
pressure and moves down by gravity. The extended part of the cylinder is
completely filled with oil. As the lift cylinder is ex- tended it pushes up on a
crosshead. This crosshead is connected to the mast with a set of wheels and
chains. The chains lift the mast at twice the lift cylinder rate.
TILT CYLINDERS (2). Double acting cylinders which extend by
hydraulic pressure and retract by hydraulic pressure. Control the forward-
Side shift cylinder
backward tilt angle of the mast. Total movement is 17 degrees;
Side tilt cylinders
Container lock cylinder(s)
SIDE SHIFT CYLINDER. A double acting cylinder which controls the
side shift of the forks and tophandler with respect to the center line of the
Oil flows from hydraulic tank (1) to hydraulic pump (2) then to control valve
vehicle. Total movement from left to right is 24 inches.
(4). The control levers are moved to let oil go through the control valve to lift
cylinder (5), tilt cylinders (6), side shift cylinder (7), side tilt cylinder (8) or
SIDE TILT CYLINDER. A double acting cylinder which rotates the
container lock cylinders (9). Oil returns from the cylinders through the control
forks and tophandler. Total movement is 10 degrees.
valve and back to the tank.
CONTAINER LOCK CYLINDERS. Double acting cylinders which lock
HYDRAULIC TANK. The storage reservoir for all of the hydraulic oil
or unlock the container. On the 20 ft tophandler there is one cylinder; on the
used in the machine except for the transmission and torque converter.
35 ft and 40 ft there are two.
Equipped with an inlet strainer for filtering oil when added. A filter is built into
the tank for filtering oil returning from the hydraulic system. A sensor is also
in the tank to monitor the oil temperature.
HYDRAULIC PUMP. A gear type, driven by the engine. Supplies oil to
the control valve for distribution to the hydraulic system.
FILTER. Protects the system in the event of a pump failure. It is a
replaceable screen type.
CONTROL VALVE. Directs high pressure oil to hydraulic
cylinders, depending on the position of one of the five control
handles. The five control valves activate the mast up and down,
tilt forward and back, slide shift left and right, slide tilt, and the
container locks. All valves contain an oil pressure relief valve to
return extra oil pressure back to the hydraulic tank when the
mast is fully tilted, fully raised, fully shifted or fully rotated.