Hoist and traction machine with free rotation control

A hoist and traction machine comprising:

• a load sheave;
• a driving shaft, provided with a driven member for driving said load sheave;
• a driving member threadingly engageable with said driving shaft;
• a braking pawl;
• a braking ratchet wheel engageable with said braking pawl;
• braking plates interposed between said driving member and said driven member and constituting a mechanical brake, driving means for normally and reversely driving said driving member;
• a free rotation control means for selectively placing said mechanical brake in an unengaged state and enabling said load sheave to freely rotate, said free rotation control means comprising:
• a) a stopper provided at an axial end of said driving shaft;
• b) an operating handle interposed between said stopper and said driving member;
• said operating handle being axially movable from a first position, in proximity to said driving member, to a second position, apart therefrom, and being non-rotatable with respect to said driving shaft;
• c) an elastically biasing member, interposed between said stopper and said operating handle, for biasing said operating handle toward said first position such that said operating handle moves toward said driving member;
• d) regulation means, provided between said operating handle and said driving member, for regulating a relative rotation range of said driving member with respect to said driving shaft when said operating handle is put in the first position, and for releasing said regulation when said operating handle is put in the second position, and
• e) free rotation control holding means for releasing regulation by putting said operating handle in the second position and, when said operating handle rotates in free rotation, applying a biasing force by said elastically biasing member onto said driving member so as to maintain free rotation operation of said operating handle;
• wherein said driving shaft has a positioning portion for setting the first position of said operating handle, the first position of said positioning portion being a position where said operating handle is not in contact with said driving member.

A hoist and traction machine comprising:

• a load sheave;
• a driving shaft, provided with a driven member for driving said load sheave;
• a driving member threadingly engageable with said driving shaft;
• a braking pawl;
• a braking ratchet wheel engageable with said braking pawl;
• braking plates interposed between said driving member and said driven member and constituting a mechanical brake, driving means for normally and reversely driving said driving member;
• a free rotation control means for selectively placing said mechanical brake in an unengaged state and enabling said load sheave to freely rotate, said free rotation control means comprising:
• a) a stopper provided at an axial end of said driving shaft;
• b) an operating handle interposed between said stopper and said driving member;
• said operating handle being axially movable from a first position, in proximity to said driving member, to a second position, apart therefrom, and being non-rotatable with respect to said driving shaft;
• c) an elastically biasing member, interposed between said stopper and said operating handle, for biasing said operating handle toward said first position such that said operating handle moves toward said driving member;
• d) regulation means, provided between said operating handle and said driving member, for regulating a relative rotation range of said driving member with respect to said driving shaft when said operating handle is put in the first position, and for releasing said regulation when said operating handle is put in the second position, and
• e) free rotation control holding means for releasing regulation by putting said operating handle in the second position and, when said operating handle rotates in free rotation, applying a biasing force by said elastically biasing member onto said driving member so as to maintain free rotation operation of said operating handle;
• said machine further comprising an overload prevention mechanism wherein:
• said driving member comprises a first driving member having a boss threadingly engageable with said driving shaft and a larger diameter portion opposite to said braking plate at said mechanical brake and a second driving member rotatably supported on said boss of said first driving member, said boss at said first driving member supporting friction plates and an elastic member and threadingly engaging an adjusting member for changing a biasing force of said friction plates caused by said elastic member so as to adjust a slip load, said adjusting member provided with regulation portions for regulating a relative rotation range of said driving member with respect, to said driving shaft at the first position of said operating handle, and free rotation control surfaces, with which said handle comes into elastic contact, for maintaining free rotation of said driving shaft by said operating handle.