Implements or apparatus for applying pushing or pulling force – Apparatus for hauling or hoisting load – including driven... – Device includes rotatably driven – cable contacting drum
Patent
1990-08-23
1992-12-01
Matecki, Katherine
Implements or apparatus for applying pushing or pulling force
Apparatus for hauling or hoisting load, including driven...
Device includes rotatably driven, cable contacting drum
254316, 318 53, 318 66, B66C 1338, B66D 168
Patent
active
051674017
ABSTRACT:
A hoist drive for a double hoist carrying member having a hold hoist drum, a hold rope connected to the hold hoist drum and from which the carrying member is suspended, and a hold motor for rotating the hold hoist drum to raise and lower the carrying member. The hoist drive further includes a close hoist drum, a close rope connected to the close hoist drum and from which the carrying member is suspended, and a close motor for rotating the close hoist drum to raise and lower the carrying member. During raising of the carrying member, the hold and close motors are each supplied with a.c. power at different preselected frequencies. The hold and close motors each operate along a first pair of intersecting frequency to torque curves during a raising operation in which the hold motor curve is steeper than the close motor curve. During a lowering operation the hold and close motors operate along a second pair of intersecting frequency to torque curves in which the hold motor curve is also steeper than the close motor curve. Due to the intersection and relative slopes of the first pair and the second pair of curves, the speed of the hold motor follows the speed of the close motor during both raising and lowering operation and the motors operate at the intersection points of the pairs of curves and share the load during both raising and lowering operation.
REFERENCES:
patent: 872523 (1907-12-01), Libby
patent: 1834785 (1931-12-01), Jones
patent: 1958037 (1934-05-01), Engler
patent: 2538061 (1951-01-01), Torok
patent: 3531088 (1970-09-01), Kraschnewski
James Michael D.
Reuss Robert H.
Harnischfeger Corporation
Matecki Katherine
Ruppin Richard C.
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