Travel/lift inhibit control
First Claim
1. In a lift truck of the type comprising an electric traction motor, manually controlled speed signal generating means for generating a speed command signal voltage varying inversely with a desired speed, an extendible upright, and control means for said motor responsive to a speed control voltage for controlling the speed of said motor, the improvement comprising:
- height signal generating means operatively coupled with said upright for generating a height signal voltage varying directly with the amount of extension of said upright,logic means responsive to said speed command signal voltage and to said height signal voltage for producing the speed control voltage corresponding to the value of the larger of said signal voltages,and means for applying said speed control voltage to said control means whereby the speed of said motor is governed by only one of said signal voltages.
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Accused Products
Abstract
A lift truck of the order-picker type is provided with an automatic control system for safe-guarding the operation against certain conditions. The electronic control system is responsive to an electrical height signal corresponding to the height of the lift fork to regulate or limit the other operational functions of the truck. The speed control channel compares the speed signal with a speed command signal and produces a speed control signal of limiting value. A travel interrupt channel compares the height signal with the steering angle and interrupts the vehicle travel if the steering angle is excessive. Usually, the high speed lift is cut-off when a predetermined height is reached; the lowering of the upright is disabled at a predetermined lower limit subject to manual override.
69 Citations
10 Claims
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1. In a lift truck of the type comprising an electric traction motor, manually controlled speed signal generating means for generating a speed command signal voltage varying inversely with a desired speed, an extendible upright, and control means for said motor responsive to a speed control voltage for controlling the speed of said motor, the improvement comprising:
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height signal generating means operatively coupled with said upright for generating a height signal voltage varying directly with the amount of extension of said upright, logic means responsive to said speed command signal voltage and to said height signal voltage for producing the speed control voltage corresponding to the value of the larger of said signal voltages, and means for applying said speed control voltage to said control means whereby the speed of said motor is governed by only one of said signal voltages. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. In a lift truck of the type comprising an electric traction motor, a manually controlled speed signal generating means for generating a speed command signal corresponding to a desired speed, an extendible upright, control means for said motor responsive to a speed control voltage for controlling the speed of said motor, a manually controlled dirigible wheel and lift means for extending said upright, the improvement comprising:
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height signal generating means operatively coupled with said upright for generating a height signal voltage corresponding to the amount of extension of said upright, logic means responsive to said speed command signal voltage and to said height signal voltage for producing the speed control voltage corresponding to the value of the larger of said signal voltages, means for applying said speed control voltage to said control means whereby the speed of said motor is governed by only one of said signal voltages, steering signal generating means for generating a steering signal voltage corresponding to a steering angle of said dirigible wheel, and travel interrupt control means responsive to said steering signal voltage for deenergizing said motor to stop said lift truck when the steering signal voltage exceeds a predetermined value.
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Specification