Overhead impact sensing system
First Claim
1. A system for deactivating a movable work platform when the platform comes in relatively close proximity to an obstruction, comprising:
- means on said platform for sensing the obstruction and changing operating states from a first operating state to a second operating state; and
electrical circuit means responsive to the first operating state of said sensing means for enabling operation of said work platform following a predetermined time delay, for disabling operation of said work platform in response to said second operating state, and for thereafter overriding the disabled operation following another predetermined time delay in order to move the platform away from said obstruction and reestablish said first operating state.
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Accused Products
Abstract
An electrical deactivation circuit and a two piece overhead guard assembly including two separately movable bar members which extends upward and over the head of an operator located on the upper work platform of an aerial work platform. The guard bar members are connected to the frame of the upper work platform by a pair of movable support assemblies, the movement of which actuates impact detection induction type proximity switch means to interrupt electrical power applied to the electrical control circuits and stop the engine powering the aerial work platform. Each movable support assembly includes a pair of spring loaded mechanical subassemblies including a pair of clamp members between which is located an elongated coil spring whose stiffness is varied in accordance with the distance separation of the clamps. An inductive type proximity switch is located in the lower end portion of each spring to sense movement of the inner end of a respective guard bar member. Each proximity switch is connected in an electrial circuit having a built in time delay or lock out feature for applying power to the aerial work platform after a predetermined time delay and thereafter interrupting power when either guard bar member strikes or comes into contact with an external object or obstruction.
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Citations
20 Claims
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1. A system for deactivating a movable work platform when the platform comes in relatively close proximity to an obstruction, comprising:
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means on said platform for sensing the obstruction and changing operating states from a first operating state to a second operating state; and electrical circuit means responsive to the first operating state of said sensing means for enabling operation of said work platform following a predetermined time delay, for disabling operation of said work platform in response to said second operating state, and for thereafter overriding the disabled operation following another predetermined time delay in order to move the platform away from said obstruction and reestablish said first operating state. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification