External pendant pay-out system with anti-droop control

• US 4,492,312 A
• Filed: 06/30/1982
• Issued: 01/08/1985
• Est. Priority Date: 06/30/1982
• Status: Expired due to Fees

• Current Assignee: FMC Corporation
• Original Assignee: FMC Corporation
• Inventors: Poock, Darwin N.
• Primary Examiner(s): Basinger, Sherman D.
• Assistant Examiner(s): Johnson, R. B.
• Application Number:
  US06/393,985
• Time in Patent Office: 923 Days
• Field of Search: 212/151, 212/153, 212/159, 212/222, 212/255, 212/230-232, 212/264, 212/266-268
• US Class Current: 212/264
• CPC Class Codes: B66C 23/823 Bracing equipment acting in vertical direction

Abstract

An apparatus is disclosed for maintaining a predetermined mast-boom working angle of a pendant supported boom substantially constant during extension and retraction of the boom. One embodiment of the invention includes control means connected between the boom and the mast for detecting slight angular changes and actuating power means for paying out or drawing in sufficient pendant to return the mast-boom angle to a predetermined angle. Another embodiment utilizes electrical controls having a first potentiometer capable of detecting linear changes in the effective boom supporting length of the pendant and another potentiometer for detecting linear changes in the length of the boom, said potentiometer sending output signal ratios which vary from a predetermined output signal ratio for actuating power means that takes up or pays out sufficient pendant to return the boom to the predetermined mast-boom working angle and returns the output signal ratio to said predetermined ratio.

Claims

1. In a pendant pay-out system for maintaining the working angle of a pendant supported extensible boom substantially constant when the boom is being extended or retracted, said boom being pivoted to support means and including a pivotally supported base section having at least one boom section telescopically received therein, first power means for extending and retracting said at least one boom section, a live mast supported on said base section for pivotal movement relative thereto and having rotatable pendant supporting means on the free end thereof, and second power means for pivoting the mast between a lowered position and one of a plurality of raised working positions with one position defining a predetermined mast-boom angle, the improvement which comprises:

a fixed length pendant disposed entirely externally of said boom and trained over said rotatable means on said mast with one end portion connected to said at least one boom section and another end portion supportively connected to said base section, reversible power operated pendant haul in or pay out means operatively connected to said pendant for hauling in or paying out pendant, and control means mounted between said mast and base section being responsive to detecting slight angular deviations of said boom from said predetermined angle due to extension of the boom or retraction of the boom for actuating said reversible power operated means to respectively pay out or haul in sufficient pendant to maintain the boom at a predetermined angle and said mast-boom angle substantially constant during extension and retraction of the boom, said rotatable pendant supporting means including a first set of sheaves journaled on said mast, said reversible power means including a hydraulic ram having a movable portion and a stationary portion, means connecting said stationary portion to said mast, a second set of sheaves mounted for rotation on the movable portion of said ram, said pendant having multiple parts of pendant trained over said sets of sheaves.

2. In a pendant pay-out system for maintaining the working angle of a pendant supported extensible boom substantially constant when the boom is being extended or retracted, said boom being pivoted to support means and including a pivotally supported base section having at least one boom section telescopically received therein, first power means for extending and retracting said at least one boom section, a live mast supported on said base section for pivotal movement relative thereto and having rotatable pendant supporting means on the free end thereof, and second power means for pivoting the mast between a lowered position and one of a plurality of raised working positions with one position defining a predetermined mast-boom angle, the improvement which comprises:

a fixed length pendant disposed entirely externally of said boom and trained over said rotatable means on said mast with one end portion connected to said at least one boom section and another end portion supportively connected to said base section, reversible power operated means including a hydraulic ram mounted on said mast for hauling in or paying out pendant, and control means being responsive to detecting slight angular deviations of said boom from said predetermined angle due to extension of the boom or retraction of the boom for actuating said reversible power operated means to respectively pay out or haul in sufficient pendant to maintain said mast-boom angle substantially constant during extension or retraction of the boom, said control means including a hydraulic valve connected between said mast and said boom base section and operatively connected to said ram;

said valve being shifted to direct high pressure fluid into said ram to pay out pendant in response to detecting a decrease in said predetermined angle, and to direct high pressure fluid into the ram to haul in pendant in response to detecting an increase in said predetermined angle.

3. In a pendant pay-out system for maintaining the working angle of a pendant supported extensible boom substantially constant when the boom is being extended or retracted;

said boom being pivoted to support means and including a pivotally supported base section having at least one boom section telescopically received therein;

first power means for extending and retracting said at least one boom section;

a live mast supported on said base section for pivotal movement relative to said base section and having rotatable pendant supporting means on the free end thereof; and

second power operated means for pivoting the mast between a lowered position and one of a plurality of raised working positions with one position defining a predetermined mast-boom angle;

the improvement which comprises;

a fixed length pendant disposed entirely externally of said boom and trained over said rotatable means on said mast with one end portion connected to said at least one boom section and another end portion supportively connected to said base section;

reversible power operated means including a hydraulic ram mounted on said live mast and operatively connected to said pendant for hauling in or paying out pendant; and

control means mounted between said mast and said base section and being responsive to detecting slight angular deviations of said boom from said predetermined angle due to extension of the boom or retraction of the boom for actuating said reversible power operated means to respectively pay out or haul in sufficient pendant to maintain said mast boom angle substantially constant during extension and retraction of the boom;

said control means including a hydraulic valve operatively connected to said reversible power means;

said valve being shifted to direct high pressure fluid into said hydraulic ram of said reversible power means to pay out pendant in response to detecting a decrease in said predetermined angle, and to direct high pressure fluid into said reversible power means to haul in pendant in response to detecting an increase in said predetermined angle.