Overload protection device in air-operated lifting devices
AssigneeAtlas Copco Aktiebolag
InventorStefan H. G. Schorling
Life of this patent
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Abstract
An overload protection device for preventing excess of allowed workload in air-operated lifting devices. A braking device is associated with a drum around which a wire is wound. Upon actuation of a control valve which controls the supply of air to a drive motor, the braking device is released. If the lifting device is overloaded, then a main valve is adjusted by means of a load sensing device and the braking device is applied by venting through the main valve.
Claims7
In an overload protection device for preventing excess of allowed workload in air-operated lifting devices, such as winches, which comprise a drum (11) for carrying a wire (23) wound therearound, a motor (12) supplied by a compressed air source (14) for driving the drum, a control valve (13) for controlling the supply of compressed air to the motor, and a braking device (22) associated with the drum (11), said braking device being supplied with compressed air for releasing thereof upon actuation of the control valve (13), the improvement comprising:
- a main valve (24) connected between the motor (12) and the compressed air source (14), and
- a load sensing device (17) which is arranged to adjust the main valve (24) by an air signal so as to stop the motor (12) due to overloading,
- the braking device (22) being adapted to be applied by venting through the main valve (24) upon an adjustment of the main valve (24) caused by the load sensing device (17).
Dependencies are inferred from the claim text.