Description
4000 SRM 135
Figure 10. Displacement Cylinders
Legend for Figure 10
NOTE: OIL LEAKAGE IS NOT CONTROLLED BY
THE TORQUE ON THE PACKING GLAND. TIGHTEN
THE PACKING RETAINER TO STOP OIL LEAKS.
REPLACE
CHEVRON-STYLE
PACKING
WHEN
PACKING RETAINER CANNOT COMPRESS PACK-
ING FURTHER TO CONTROL OIL LEAKS. DO NOT
TIGHTEN MORE THAN NECESSARY TO STOP OIL
LEAKS.
1.
WIPER
2.
NYLON RING
3.
CHEVRON-STYLE
PACKING
4.
BACKUP RING
5.
O-RING
6.
ROD HEAD
7.
PACKING
RETAINER
8.
PACKING GLAND
9.
CYLINDER SHELL
10. INLET AND
OUTLET PORT
11. WEAR RING
CYLINDERS (TWO-SPEED)
Two-speed lift cylinders are single-stage lift cylinders
with a special valve and path for the hydraulic oil.
The lift cylinder is filled with oil on both sides of the
piston. For loads less than 45% of the rated capacity,
the cylinder rod can be extended at high speed. When
the cylinder rod extends, the oil on the rod side of the
piston transfers to the bottom of the piston. When
the oil transfers, the increase almost doubles the flow
of oil to the base of the cylinder. The pump pressure
is applied to both sides of the piston. The area on the
bottom of the piston is greater than the rod side of
the piston. The difference in force pushes the piston
up the cylinder. See Figure 11.
For loads greater than 45% of capacity, the cylinder
rod extends at normal speed. A special valve senses
the increased oil pressure caused by the load. The
oil is returned from the rod side of the lift cylinder
to the hydraulic tank. All of the pump pressure is
applied to the bottom side of the piston. The cylinder
rod extends at a slower speed, but can lift a greater
load. The two-speed lifting system is used only with
standard masts. A two-speed lift system is used on
the following lift trucks:
S60-80B
H150-250E
S125-150A
H150-275H
H60-80C
H250-300A
H300-350B
P125-180A
H110-150F
P150-200B
12
