Boots – shoes – and leggings
Patent
1992-02-10
1993-01-26
Black, Thomas G.
Boots, shoes, and leggings
364184, 37DIG1, G06F 1520
Patent
active
051827131
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD OF THE INVENTION
This invention relates to a turning brake controlling system for use in a power shovel having an excavating implement mounted on the vehicle body thereof so that it can be turned.
BACKGROUND TECHNIQUE OF THE INVENTION
A turning brake controlling system for applying braking force on the upper turning body of a power shovel is arranged to be actuated automatically to apply braking force on the upper turning body when the turning brake is actuated intentionally by the operator of the power shovel or when the turning lever for turning the upper turning body is shifted to its neutral position in order to stop the turning of the upper turning body. The turning brake means is usually adapted to be actuated several seconds after the turning lever is shifted from its "turning" position to its "neutral" position, thereby preventing sudden stoppage of the upper turning body.
Since the delay time for the turning brake; that is; the time which passes from the shifting of the turning lever from its "turning" position to its "neutral" position until the actuation of the turning brake controlling system is predetermined, in the case of turning operations of the shovel on a slope, if positioning of the upper turning body in the turning direction is made by turning it slowly, then the upper turning body is turned during the delay time for the turning brake under the influence of gravity and leakage of fluid from the hydraulic motor so that it is difficult to stop it towards a target.
Further, in case the above-mentioned conventional turning brake controlling system is controlled by means of a microprocessor, if the microprocessor fails to fulfill arithmetic function as programmed for some cause such as noise or static electricity, etc., then the binary ON-OFF control signal becomes unstable, or only either ON output or OFF output can be developed. As a result, the controlling function of the turning brake controlling system is completely lost thus creating a dangerous condition, so that the operator cannot help stopping the operation.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above-mentioned circumstances, and has for its first object to provide a turning brake controlling system for use in a power shovel arranged such that even when a microprocessor for controlling the operation of a turning brake actuator means malfunctions the turning brake can be actuated several seconds after the turning lever is shifted form its "turning" position to its "neutral" position.
Further, the second object of the present invention is to provide a turning brake controlling system for use in a power shovel arranged such that when the turning speed of the upper turning body becomes lower than a predetermined value the turning brake can be actuated even if it occurs during the delay time for the turning brake, thereby eliminating free movement or turning of the upper turning body by the force of gravity, etc. during the delay time for the turning brake, and accurate positioning of the upper turning body can be made in turning it slowly when the power shovel is on a slope.
Further, the third object of the present invention is to provide a turning brake controlling system for use in a power shovel arranged such that the delay time for the turning brake may be varied with the turning speed of the upper turning body when the turning lever is shifted from its turning position to its neutral position so that in case the turning speed is slow the delay time for the turning brake is reduced, and in particular in case of slow turning operations on a slope, when the turning lever is shifted from its turning position to its neutral position, the upper turning body is prevented from turning freely under the influence of external forces such as the force of gravity, etc..
To achieve the above-mentioned objects, according to the first aspect of the present invention, there is provided a turning brake controlling system for use in an upper turning body of a power shovel arranged to rece
REFERENCES:
patent: 4377043 (1983-03-01), Inui et al.
patent: 4739469 (1988-04-01), Oshiage et al.
patent: 4748566 (1988-05-01), Sasaki et al.
patent: 4889466 (1989-12-01), Jindai et al.
Black Thomas G.
Kabushiki Kaisha Komatsu Seisakusho
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