Land vehicles – Body elevation or tilt – Terrain slope compensation
Reexamination Certificate
1998-09-28
2001-03-20
Dickson, Paul N. (Department: 3618)
Land vehicles
Body elevation or tilt
Terrain slope compensation
C280S788000, C280S755000
Reexamination Certificate
active
06203027
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a structure for supporting fluid pressure cylinders that are used to control pivoting of axles with respect to vehicle bodies.
A forklift includes a body, a rear axle supported by the body, and rear wheels mounted on the rear axle. Typically, the rear axle is pivotally supported with respect to the body. Thus, the axle pivots with respect to the body to constantly maintain traction between each wheel and the ground surface even when the forklift travels along bumpy surfaces. However, the pivotal structure of the axle may reduce the driving stability of the forklift. For example, the forklift's center of gravity may be raised due to the load being carried. In such state, if the forklift is steered in a sudden manner when changing direction, centrifugal force acting laterally on the forklift (lateral acceleration) may tilt the forklift body. Accordingly, an axle locking apparatus has been proposed to stabilize the forklift under such circumstances. The apparatus restricts the pivoting of the axle with respect to the body when a detected yaw acceleration or lateral acceleration exceeds a predetermined value.
As shown in
FIG. 4
, the apparatus includes a hydraulic cylinder
22
, which is located between a body
20
and a rear axle
21
. The cylinder has two hydraulic oil chambers that are connected to each other by a passage. An electromagnetic valve
23
is arranged in the passage. The electromagnetic valve
23
closes the passage to stop the movement of hydraulic oil between the two oil chambers. This locks the hydraulic cylinder
22
and prohibits pivoting of the rear axle
21
with respect to the body
20
. To permit pivoting of the rear axle
21
relative to the body
20
, the electromagnetic valve
23
opens the passage. This allows movement of hydraulic oil between the two oil chambers and thus unlocks the hydraulic cylinder
22
.
An upper bracket
24
is welded to the body
20
to support the hydraulic cylinder
22
. As shown in
FIGS. 4 and 5
, the upper bracket
24
has a base plate
27
and a pair of parallel support plates
28
fixed to the base plate
27
. An upper pin
25
is supported by the support plates
28
and is parallel to the pivoting axis of the rear axle
21
. The hydraulic cylinder
22
has a cylinder tube. An upper anchor
26
having a bore is defined at the top portion of the cylinder tube. The upper anchor
26
is held between the support plates
28
with the upper pin
25
extending through the anchor bore. Accordingly, the hydraulic cylinder
22
is pivotally connected to the body
20
.
As shown in
FIG. 4
, a lower bracket
30
is fixed to the rear axle
21
. A lower pin
29
is supported by the bracket
30
and is parallel to the pivoting axis of the rear axle
21
. A lower anchor
26
having a bore is defined at the bottom portion of the cylinder tube. The lower pin
29
extends through the bore of the lower anchor
26
. This pivotally connects the hydraulic cylinder
22
to the rear axle
21
.
The upper bracket
24
is produced exclusively to connect the hydraulic cylinder
22
to the body
20
. However, the employment of the single-purpose bracket
24
not only increases the number of components required to support the hydraulic cylinder
22
but also complicates the structure for coupling the hydraulic cylinder
22
to the body
20
. Thus, the employment of the bracket
24
results in additional tasks during production of the forklift and thus lowers efficiency.
SUMMARY OF THE INVENTION
Accordingly, it is an objective of the present invention to provide a simplified structure for coupling fluid pressure cylinders, which control pivoting of axles, to vehicle bodies.
To achieve the above objective, the present invention provides a structure for supporting a fluid pressure cylinder that is used to control pivoting of a vehicle axle. The axle is supported pivotally with respect to a vehicle body. The fluid pressure cylinder includes an upper end pivotally connected to the body by an upper joint, a lower end pivotally connected to the axle by a lower joint, and a movable piston rod. Pivoting of the axle is permitted when movement of the piston rod is permitted and restricted when movement of the piston rod is restricted. The support structure includes a framework constituting part of the body. The framework directly supports the upper joint.
Other aspects and advantages of the present invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.
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Ishikawa Kazuo
Niwa Yasuhiro
Dickson Paul N.
Kabushiki Kaisha Toyoda Jidoshokki Seisakusho
Morgan & Finnegan L.L.P.
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