Motor vehicles – Manually actuated controlling devices – Multiple vehicle functions controllable by single device
Patent
1993-09-01
1995-12-19
Culbreth, Eric D.
Motor vehicles
Manually actuated controlling devices
Multiple vehicle functions controllable by single device
74471XY, 192 12C, 192 13R, 192 17A, B60K 2600
Patent
active
054761522
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a steering control system for controlling steering operations such as forward, rearward, rightward and leftward movements of a construction equipment, such as a bulldozer, by a single control lever and, more particularly, a steering control system for controlling operations of a rightward/leftward steering clutch and a brake by hydraulic pilot pressure.
BACKGROUND OF THE INVENTION
This kind of control has conventionally employed a steering control system capable of controlling forward, rearward, rightward and leftward operations, particularly to be controlled by a single control lever by only a wrist work of the left hand with the left elbow being kept on a left side arm rest. In this case, a construction vehicle moves forwardly when the control lever is shifted from the neutral position to the forward position and moves rearwardly when the lever is shifted to the rearward position, and is steered to the left when the lever is shifted to the left and to the right when the lever is shifted to the right. Though there is no problem in control operations for forward and rearward movement, a mechanical linkage type steering control system comprising a plurality of control levers and rods in combination as shown in FIG. 3 has been employed for transmitting operating forces of these control levers and rods to actuate the clutch and the brake. FIG. 3 shows an example of the steering control system provided with two exclusively used control levers rather than with a single control lever. In this case, a rod type control lever 21 is connected to one end of a lever 23 having a pivotal point 22 and one end of a rod 24 is connected to the other end of the lever 23. The other end of rod 24 is coupled to a brake lever 25 and, when the brake lever 25 is actuated around the pivotal point 26 as a center, a brake 28 is ON and OFF-operated through a lever 27. A loose spring 29 is coupled to this brake lever 25 and the other end of this loose spring 29 is coupled to a steering control clutch valve 31 through a lever 30. When this steering control clutch valve 31 is actuated, a hydraulic pressure is applied to a clutch piston 32 through a piping 33 and the clutch 34 is disengaged. In the drawing, 35 and 36 denote gears and 37 denotes a spring.
However, this mechanical linkage type steering control system is disadvantageous in that the construction is complicated, transmission efficiency is low, operation strokes of control means are long and operating forces required are heavy. This type of steering control system is accompanied by the problem that, when the brake is worn out, the operation strokes vary and a force for tightening the brake band does not respond to control operation.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a steering control system by pilot pressure and eliminate disadvantages of the prior art.
The present invention, therefore, specifies to couple the lever to a pilot pressure control valve during rightward and leftward steering and connect this pilot pressure control valve to the clutch piston for ON and OFF-operating the clutch and to the brake cylinder for ON and OFF-operating the brake with a piping, respectively. This pilot pressure control valve has the positions for the clutch system and the brake system at the left side and also the positions for the clutch system and the brake system at the right side, whereby the positions for the clutch systems at the right and left sides and the positions for the brake systems at the right and left sides are arranged in alternate crossing layout, and these four positions in the circuitry are independent.
When the control lever is shifted to right or left during rightward and leftward steering operation, the pilot pressure control valve at the side where the control lever is operated is actuated to set the associated clutch to OFF by the pilot pressure of the clutch system position and subsequently the associated brake to ON by the pilot pressure of the brake system positi
REFERENCES:
patent: 3677632 (1972-07-01), Chatterjea
patent: 4078628 (1978-03-01), Reichenberger
patent: 4175649 (1979-11-01), Monks
patent: 4404991 (1983-09-01), Cullen
patent: 4559844 (1985-12-01), Mor
patent: 5375686 (1994-12-01), Yamamoto
Oikawa Masazumi
Yamamoto Yukyu
Culbreth Eric D.
Kabushiki Kaisha Komatsu Seisakusho
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