cylinder raises the carriage to the top of the inner
rail. After the center cylinder reaches the end of
its stroke, the outer lift cylinders begin to extend.
As the outer cylinders extend, the middle rail is
raised. The inner rail is raised by the lift chains.
During lowering, the outer lift cylinders retract first
because they have the greater load and the
smaller area. After the outer cylinders have
retracted, the center cylinder lowers. All oil from
the lift cylinders flows through the lowering control
valve which limits the lowering speed. Flow fuses
at each cylinder port close to prevent the mast
from dropping in the event of a sudden outrush of
oil from a broken hose or tube. Once the problem
has been repaired, raise the mast to reset the flow
fuses.
Safety Procedures When Working on
the Mast
The following procedures must be used when
inspecting or working on the mast. Additional
precautions and procedures can be required
when repairing or removing the mast.
WARNING
Mast parts are heavy and can move.
Distances between parts are small. Serious
injury or death can result if part of the body is
hit by parts of the mast or carriage.
Ÿ
Never put any part of the body into or
under the mast or carriage unless all parts
are completely lowered or safety chains
are installed. Also make sure the power is
off and the key is removed. Put a “DO
NOT OPERATE” tag in the operator
compartment.
Ÿ
Be careful of the forks. When the mast is
raised, the forks can be at a height to
cause injury.
Ÿ
DO NOT climb the mast or lift truck at any
time. Use a ladder or personnel lift to
work on the mast.
Ÿ
DO NOT use blocks to support the mast
rails or to restrain their movement.
Ÿ
Mast repairs require disassembly and
removal of parts and can require removal
of the mast or carriage. Follow the repair
procedures in this manual.
E
lectric
C
ounterbalance
H
igh
O
utput
Elevating
3/10/00
7.3
FIGURE 7.4 - HYDRAULIC SCHEMATIC
