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US 4,392,771 AGranted
Lift safety switch system
AssigneeREB Manufacturing, Inc.
InventorRaymond L. Smalley
Life of this patent
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AssigneeREB Manufacturing, Inc.
InventorRaymond L. Smalley
Estimating the term…
An electrically controlled hydraulic lift, such as wheelchair lifts for vehicles, wherein the hydraulic reciprocating motor for operating the platform of the lift is mounted in a vertical slot so that any obstruction in the downward movement of the platform of the lift will cause the reciprocating motor to rise in the slot and operate a microswitch to automatically shut off the continued supply of fluid to the reciprocating motor. This arrangement not only prevents the crushing of obstacles that get in the downward path of the platform, but also limits the downward movement of the platform when it contacts the solid ground or floor level from which an object is to be lifted, such as an invalid in a wheelchair. If desired, the upward movement of the reciprocating hydraulic motor may be restricted by resilient means for maintaining it in the lower part of its mounting slot. The electrical control system for the supply of hydraulic pressure fluid to the reciprocating motor may also include a limit switch along the vertical path of movement of the platform. The fluid pressure supply may comprise an integral hydraulic pump and electric motor assembly unit having high and low pressure fluid outlets for respectively operating the reciprocating motor for raising and lowering the lift platform.
In a fluid-operated lift comprising:
Dependencies are inferred from the claim text.