Overload protection apparatus for hoisting machine
AssigneeHitachi, Ltd.
InventorKoki Hirasuka
Life of this patent
Estimating the term…
Abstract
The disclosure relates to an overload protection apparatus for hoisting machine such as rope hoists or chain blocks. The apparatus has a slipping gear unit and a ratchet gear unit which are arranged on a shaft in a reduction gear assembly. The ratchet gear unit is adapted to be applied with a torque only when the hoisting machine is lowering the load, so as to impart an additional functional force to the slipping gear unit during a braking.
Claims5
In an overload protection apparatus for hoisting machines having a driving part including an electric motor, an output, and a reduction part interconnecting said driving part and said output, with said reduction part having parallelly disposed input and output shafts, the improvement comprising:
- a slipping gear unit and a ratchet gear unit which are mounted drivingly connected between said input and said output shafts, said slipping gear unit and said ratchet gear unit respectively having outer ring gears engaging with said input shaft, said slipping gear unit having means to slip for torques exceeding a predetermined torque, said ratchet gear unit having ratchet means to engage its ring gear when said output shaft is rotated in a direction for lowering the load carried by said hoisting machine at a speed exceeding a predetermined speed, said slipping gear unit ring gear having inwardly extending protrusions, gear retaining plates for clamping said ring gear at its opposite sides and a spring acting between said protrusions and said plates for biasing said protrusions and said plates to one extreme position of limited relative lost motion and being compressed as said protrusions and said plates move to the opposite extreme position of the limited relative lost motion when transmitting torque between said input shaft and said output shaft.
An overload protection apparatus for a load hoist having a power source and a speed reduction unit drivingly connected with the power source, comprising:
- a rotary input member, a rotary output member, a torque responsive overload coupling drivingly connected between said input member and said output member for permitting relative rotation between said input member and said output member when the torque on said output member exceeds a fixed value to prevent overloading, speed responsive means to automatically drivingly engage said input member with said output member to transmit torque substantially higher than said fixed value when the speed of rotation of said output member exceeds a fixed value, said overload coupling including a first member positively interengaged with one of said input members and said output members and a second member frictionally engaged with the other of said input members and said output members, said first and second members being interconnected for limited relative rotational lost motion about the axis of rotation of said output member, and spring means between said first member and said second member for biasing said first and second members to one extreme position of the limited relative lost motion and being compressed as said first and second members move to the opposite extreme position of the limited relative lost motion when transmitting torque between said input member and said output member;
- said spring means storing energy upon transferring torque and releasing the energy when the load is released from the hoist to relatively rotate said second member and said first member from said other extreme position to said one extreme position and thereby assure disengagement of said speed responsive means.
Dependencies are inferred from the claim text.