Vehicle equipped with balancing device

The invention relates to cargo-handling vehicles and the like which comprise a handling device such as a bucket or a fork. A balancing device in equipped either at the front or the rear of the vehicle in such a way as to be rotatable on an axle which is horizontal and at right angles to the running direction of the vehicle, the balancing device comprising a balance weight coupled with a vehicle body by the axle, and an elastic body and a shock absorber provided between the balance weight and the vehicle body. Pitching phenomenon of a cargo-handling vehicle or the like can be automatically restrained in a responsive manner. It is possible to prevent the vehicle from overturning caused by an unexpected imbalance. The running stability can be improved and a comfortable ride accomplished.

FIELD OF THE INVENTION 
This invention relates to various industrial vehicles such as 
cargo-handling vehicles having handling devices like a bucket or a fork at 
the front, and work vehicles like tractors. 
BACKGROUND OF THE INVENTION 
While cargo-handling vehicles and work vehicles mentioned above are 
running, their front wheels react to the unevenness of the road, causing 
the body of the vehicle to pitch and bound, thus requiring some control to 
slow down the running speed. The conventional countermeasures to this kind 
of problem are, as presented in the Japanese Laid Open Patent No. 
63-265024, to equip a vibration-reducing accumulator to the hydraulic 
cylinder for operating the handling device by means of outside piping 
through a mode switching valve, and as shown in the Japanese Utility Model 
Publication No. 60-3159 to provide a balance weight at the rear of the 
vehicle body through a balancing cylinder. However, both of the 
conventional systems utilize a hydraulic system and accordingly have poor 
responsiveness, being unable to preferably control the pitching in spite 
of their complicated structures. Besides, the conventional systems require 
such controls as to operate the switching valve, thus having a 
disadvantage that the booms may be lowered by the switching. 
DISCLOSURE OF THE INVENTION 
The purpose of this invention is to provide a vehicle equipped with a 
balancing device which is responsive and requires no control. 
In order to achieve this purpose, the present invention provides a vehicle 
equipped with a balancing device either at the front or the rear of the 
vehicle, wherein; 
the balancing device is rotatable around an axle which is horizontal and at 
right angles to the running direction of the vehicle, the balancing device 
comprising; 
a balance weight coupled with a vehicle body by means of the axle, and 
elastic body means and shock absorbing means provided between the balance 
weight and the vehicle body. 
When the wheels of the vehicle react to the unevenness of a road while 
running, pitching of the main body may occur. For example, when such 
pitching occurs as to lower the cargo device mounted at the front of the 
vehicle, the main body of the vehicle bears a rotation moment to raise the 
rear portion of the vehicle with respect to the axis of the center of the 
inertia moment of the vehicle. Further, for example, when the front wheels 
run over any kind of obstacle, the main body of the vehicle bears a 
rotation moment to raise its front portion. In these cases, according to 
the present invention where a balancing device is so equipped either at 
the front or the rear of the vehicle as mentioned above, the balance 
weight of the balancing device reacts against the elastic body and shock 
absorber to rotate on the aforesaid axis in the opposite direction of the 
aforesaid rotation moment, consequently decreasing the rotation moment. 
As a result, the pitching phenomenon is automatically restrained in a 
responsive manner with no control. Hence, it is possible to prevent the 
vehicle from overturning according to an unexpected disturbance of the 
balance and improve the running stability accomplishing a more comfortable 
ride.

PREFERRED EMBODIMENTS 
Following are the description of the preferred embodiments of the present 
invention in accordance with FIGS. 1 to 5. 
In FIG. 1, numeral 1 represents a main body of a vehicle having plural 
wheels 2, installed on which is a driver's cab 3 with a seat, levers and 
the like. At the front of vehicle body 1, a handling device 4 is mounted. 
To be more precise, at the front of the driver's cab 3, a pair of booms 5 
are arranged, with their base ends connected to the brackets 6 protruding 
from the vehicle body 1 by means of a shaft 7, enabling the booms 5 swing 
up and down. Mounted between the vehicle body 1 and the booms 5 is a 
loading cylinder 8 which swingably drives the booms 5. A bucket 10 is 
attached between the free ends of the booms 5 by means of a lateral pin 9, 
and the free end of a first link 12A attached to the booms 5 by means of a 
pin 11 and the base end of a second link 12B are coupled by means of a pin 
19. The free end of the second link 12B and the bucket 10 are linked by 
means of a pin 13. A cylinder 14 is mounted between the base end of the 
first link 12A and the booms 5 so as to make the said bucket 10 rotate 
around the lateral pin 9. A balance weight 16 is swingably attached to 
vehicle body 1 by means of a lateral axle 15 which is horizontal and at 
right angles to the running direction of the vehicle. A tensile spring 17 
(an example of elastic body means) and a shock absorber 18 are provided 
between the vehicle body 1 and the balance weight 16. The number of 
tensile springs 17 and shock absorbers 18 are properly determined 
depending on the weight of the balance weight 16 and other relavant 
factors. 
When the cargo-handling vehicle with its unloaded handling device 4 raised 
up is driven, if the wheels 2 react to the uneven surface of the road, the 
vehicle body 1 is caused to pitch. When such pitching as to lower the 
booms 5 (arrow B) occurs while the vehicle runs, the vehicle body 1 bears 
near its front wheels a rotation moment C which will raise the rear 
portion of the vehicle body 1. As a result, the balance weight 16 bears a 
rotation moment D which is produced with respect to the lateral axle 15 
against the tensile spring 17 and the shock absorber 18 in the opposite 
direction of the rotation moment C. Both rotation moments C, D 
counterbalance each other so as to decrease rotation moment C, thus the 
pitching motion abates. When the vehicle body 1 bounds upward (parallel 
movement), the balance weight 16, due to the inertia moment, reacts to 
remain in the orignal position, so that the vehicle body 1 is forced 
downward to decrease its bound. 
FIG. 2 represents the second embodiment where a balance weight 16 is 
arranged to be swingable at a position beneath a frame 20 by means of a 
lateral axle 15 which is horizontal and at right angles to the running 
direction. A tensile spring 17 and a shock absorber 18 are provided 
between the balance weight 16 and the frame 20. 
When the frame 20 is to be raised in the direction of a rotation moment C, 
the balance weight 16 bears a rotation moment around the lateral axle 15 
in the opposite direction to the rotation moment C against the tensile 
spring 17 and the shock absorber 18. Thus the rotation moment C can be 
decreased and the pitching phenomenon restrained. 
FIG. 3 represents the third embodiment of the present invention where a 
balance weight 16 is provided at the front of a vehicle body 1 by means of 
a lateral axle 15 which is horizontal and at right angles to the running 
direction of the vehicle. A tensile spring 17 and a shock absorber 18 are 
provided between the vehicle body 1 and the balance weight 16. Another 
balance weight 22 is added at the rear of the vehicle body 1. 
When front wheels run over any kind of obstacle and such rotation moment E 
is produced as to raise the front portion of the vehicle body 1, the 
balance weight 16 bears a rotation moment F around the lateral axle 15 in 
the opposite direction of the rotation moment E against the tensile spring 
17 and the shock absorber 18. Both rotation moments E and F counterbalance 
each other to decrease the rotation moment E. 
Arranged at the rear of the vehicle body 1 is a balance weight 22 which is 
attached to the vehicle body 1 rigidly. 
FIG. 4 shows another embodiment of the present invention. This embodiment 
is based on a concept that different modes of oscillation generated by 
different loads or different force inputs on the vehicle should be 
attenuated by means of different balance weights, i.e., a first balance 
weight 22 and a second balance weight 16. 
The first balance weight 22 having a central recess 23 is pivotally 
connected to the rear end of the vehicle body 1, and the balance weight 16 
is placed in the recess 23. The balance weight 16 is attached to the 
balance weight 22 by means of a lateral axle 15 the longitudinal axis of 
which is horizontal and rectangular to the running direction of the 
vehicle so as to enable the balance weight 16 to swing around the 
longitudinal axis of axle 15. Tensile springs 17 and shock absorbers 18 
are provided between the balance weights 16 and 22. 
Means for yieldingly biasing the first balance weight 22 includes springs 
27 and dashpots 28 connected between the vehicle body 1 and the first 
balance weight 22. The spring constant of the springs 27 and the 
attenuation coefficient of the dashpots 28 are larger than the spring 
constant of the springs 17 and the attenuation coefficient of the dashpots 
18. Preferably the horizontal axle 15 extends parallel with a horizontal 
axle 29 about the longitudinal axis of which the first balance weight 22 
is adapted for pivotal movement. 
The central recess 23 opens through the upper surface 30, bottom surface 
and rear surface 31 of the first balance weight 22, and has an inner 
surface 32 which is parallel with the rear surface 31 of the first balance 
weight 22. The second balance weight 16 is pivotally connected to this 
inner surface 32 for pivotal movement about the longitudinal axis of 
horizontal axle 15. 
Although only a cargo-handling vehicle having a bucket 10 at the front is 
shown in each of the aforesaid embodiments, work vehicles like tractors 
can be represented in these embodiments. Moreover, the handling device can 
be replaced by a fork device. 
In this connection, FIG. 5 shows the fifth embodiment of the present 
invention in respect of a fork lift. A handling device 4 mounted at the 
front of a vehicle body 1 is consisted of a mast 24 and a fork 25. This 
kind of fork lift is subject to pitching while running with load 26, since 
the center of gravity moves toward the front of the vehicle according to 
the weight of the load 26. If the vehicle body 1 is provided with a 
balance weight 16 being able to swing around a lateral axle 15 the axis of 
which is horizontal and at right angles to the running direction of the 
vehicle, pitching can be decreased. If the front wheels run over some 
obstruction and later fall down therefrom, the rear wheels would spring up 
in the direction of the arrow H, so that a shock absorber 18 moves toward 
the direction of the arrow I and absorbs the swing motion. In addition to 
this balancing effect while running, a similar behavior takes place even 
when load 26 is rapidly lowered by misoperation and then stopped. This is 
a great advantage to safety. 
Tensile springs (coil springs) shown in the aforesaid embodiments as an 
elastic body can be replaced by compression springs, leaf springs or 
torsion springs.