Motor vehicles – Steering gear – Each wheel steerable
Reexamination Certificate
2002-07-24
2004-09-21
Hurley, Kevin (Department: 3611)
Motor vehicles
Steering gear
Each wheel steerable
C280S103000
Reexamination Certificate
active
06793036
ABSTRACT:
TECHNICAL FIELD
This invention relates to a working vehicle with transverse system, which can be switched to a transverse travel mode.
BACKGROUND ART
Conventionally, working vehicles having a transverse system have primarily been found among large size conveyance vehicles and some loaders, and reach style electric vehicles as forklifts. In addition, there exists a side forklift with a mast and forks installed sideways in relation to the movement direction of the vehicle to allow the vehicle to handle elongated objects. However, there are no counter balance type forklifts that can move sideways and function like a side forklift in addition to such tasks as generally required. To realize this type of forklift, the front wheels or driving wheels are required to be steerable sideways.
Therefore, a conventional forklift
1
, shown in
FIG. 14
, has a pair of right and left front wheels
3
(driving wheels) in a front part of a vehicle body
2
, a pair of right and left rear wheels
4
in a rear part of the vehicle body
2
, and a driver's seat
5
on an upper front part of the vehicle body
2
. A mast
6
capable of vertically extending and retracting is located at a front end of the vehicle body
2
to be able to tilt in a front-and-rear direction through a linking axle
7
extending in the direction of the vehicles' width. Additionally, tilt cylinders
8
enabling the mast
6
to tilt forward and backward are placed between the vehicle body
2
and the mast
6
.
The mast
6
comprises a pair of right and left outer frames
9
and a pair of right and left inner frames
10
capable of vertical movement by being guided by the outer frames
9
. Disposed between the outer frames
9
and the inner frames
10
is a lift cylinder
11
. Additionally, lift brackets
12
capable of vertical movement by being guided on the inner frames
10
are provided, and a pair of right and left forks
13
are secured to the lift brackets
12
through a pair of upper and lower finger bars.
The above mentioned driver's seat
5
includes a seat
15
, a steering wheel
16
located in front of the seat
15
, and a headguard
19
disposed thereabove through front pipes
17
and rear pipes
18
which are erected on the vehicle body
2
. A counterweight is located in the rear of the seat
15
on the vehicle body
2
.
However, since the right and left front wheels
3
are driven in common by a same travel drive system, the above mentioned conventional forklift
1
cannot effect straight-sideways steering of the front wheels, thus being unable to move laterally.
DISCLOSURE OF INVENTION
The first objective of the present invention is to provide a working vehicle with a transverse system, in which driving front wheels can be steered straight sideways, and in the transverse travel mode, assisting in straight driving and attitude control such as changing a direction of a vehicle body (vehicle) can be achieved at a specified speed.
The second objective of the present invention is to provide a working vehicle with a transverse system, in which the driving front wheels can be steered straight sideways and angle adjustment of the front wheels can be made easily and precisely.
To achieve the first objective mentioned above, a working vehicle with a transverse system according to Claim
1
of the present invention comprises a pair of right and left front wheels and a pair of right and left rear wheels, respectively capable of steering, each of the pair of right and left front wheels being linked to a drive shaft on the travel drive system side, wherein each travel drive system is secured to a swing member capable of rotating around a vertical axis of the vehicle body, a means for rotating swing member is provided to allow a hydraulic operating device to rotate both swing members against each other, and a switching valve means is secured to a piping between a hydraulic pump and a working control valve, whereby the piping on a side to be switched by the switching valve means is connected to a control valve for the hydraulic operating device through a flow divider.
According to the above mentioned configuration of Claim
1
of this invention, the switching valve means during the normal travel mode is in a one-way switching condition, which will enable the full flow of pressure oil to be fed to the working control valve from the hydraulic pump. The hydraulically operating device is in the neutral position to steer the right and left front wheels in the front and rear directions. This type of working vehicle can drive both forward and backward and can operate various working functions through the working control valve.
Switching from the normal travel mode to the transverse travel mode is accomplished by switching a switching valve means into an opposite-way switching condition, thus full flow of pressure oil from the hydraulic pump can be fed directly to the flow divider which controls the flow to allow a specific amount of the flow to flow to the control valve for the hydraulic operating device.
This control valve for the hydraulically operating device controls only the pressure oil required for steering to allow oil to flow to the hydraulically operating device so as to operate the hydraulically operating device to rotate both swing members around a vertical axis, thereby to steer both front wheels through 90 degrees (steer straight sideways) in relation to the vehicle body. Because of the fact that both front wheels are respectively integrated with the travel drive system, the 90-degree steering can be achieved easily. Thus, after having steered both front wheels straight sideways, the front wheels are controllably rotated in either to-and-fro directions thereof by the travel drive system, whereby the working vehicle can travel laterally either to the right or left with respect to the vehicle body. At this time, the rear wheels are allowed for follow-up steering by means of a turning castor system or can be forcedly steered following the front wheels.
Further, when traveling transversely, or when the traveling mode is switched to the transverse traveling by steering for 90 degrees, the misalignment of straight-ahead driving due to poor road surface conditions and weight imbalance (load fluctuation between front and rear) can be corrected easily by operating the hydraulic operating device slightly to steer both front wheels facing inward or outward through a smaller angle. In addition, by steering both front wheels inward or outward, the direction of the working vehicle can be slightly changed during transverse traveling and the vehicle can also be turned during transverse traveling.
Since the flow divider is capable of controlling the flow to allow specific amount of flow to flow to the control valve for the hydraulic operating device irrespective of the flow rate of pressure oil from the hydraulic pump, steering both front wheels and posture control (correction of straightness) during transverse travel can be achieved and maintained at a specified speed easily and smoothly at all times.
To achieve the second objective mentioned above, the working vehicle with transverse system in Claim
2
of this invention, comprising a pair of right and left front wheels and a pair of right and left rear wheels mounted to a vehicle body, respectively to be capable of steering by 90 degrees, wherein each of the pair of right and left front wheels is linked to a drive shaft on the side of a travel drive system being secured to be capable of freely rotating around a vertical axis with respect to the vehicle body, wherein a rotating means is provided to have a turning cylinder which can be extended and contracted through a control valve by operating a transverse travel switch lever, a transverse control lever is secured separately from said transverse travel lever, to be capable of operating in a specified range, and there are provided a means for detecting a tilt location of said transverse travel lever and a means for detecting the steering angle of the front wheels, whereby outputted detected values from these detecting me
Enmeiji Yoshiyuki
Nishikawa Takeshi
Fildes & Outland, P.C.
Hurley Kevin
TCM Corporation
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