Patent ID: 11945704
Assignee: OSHKOSH CORPORATION
Field: Handling (Mechanical engineering)
Classification: CPC B  F  H | IPC B  F  H

Claim 8:
9. A lift device comprising:
a base having a plurality of wheels;
a retractable lift mechanism having a first end coupled to the base and being moveable between an extended position and a retracted position;
a work platform configured to support a load, the work platform being coupled to and supported by a second end of the retractable lift mechanism;
a linear actuator configured to selectively move the retractable lift mechanism between the extended position and the retracted position, the linear actuator having an electric motor; and
an electromagnetic brake coupled to the linear actuator and movable between an engaged position, in which the retractable lift mechanism is prevented from moving between the extended position and the retracted position, and a disengaged position, in which the retractable lift mechanism is allowed to move between the extended position and the retracted position, the electromagnetic brake being biased toward the engaged position in the event of a power failure;
a manual release device configured to manually move the electromagnetic brake from the engaged position to the disengaged position, wherein the electric motor of the linear actuator of is a permanent magnet motor having terminals that are biased toward a shunted position, such that, in the event of the power failure, when the electromagnetic brake is moved into the disengaged position by the manual release device and the work platform is being lowered, the permanent magnet motor acts as a generator, electromagnetically reducing a rotational speed of a rotor of the electric motor and, thereby, reducing the speed at which the retractable lift mechanism is moved from the extended position to the retracted position.