Pump jack

Details Pump jack Pump jack

1989-03-21

1990-09-11

Hartman, J. J.

Fire escape, ladder, or scaffold

Pole or strand grasping-type climber

254106, 182136, A63B 2700

Patent

active

049555847

ABSTRACT:
A pump jack for traveling up and down a pole includes a frame member which supports a lower shackle having a front and a rear gripping rods applying a clamping force for gripping the pole. A pump arm pivotally supports and operates an upper shackle also having a front and a rear gripping rod for clamping the pole. The lower shackle has a single U-shaped yoke pivotally supported on and biased to a support arm to improve the leverage for operating the lower shackle. The upper shackle is provided with a freely rotatable roller mounted on the upper shackle so as to space the bitting front rod of the upper shackle from the pole to permit stepping up of the upper shackle. The usual tension springs on the upper shackle are eliminated to thereby permit less force needed for its operation.

REFERENCES:
patent: 4008785 (1977-02-01), Mugnaini
patent: 4411335 (1983-10-01), Forrester
patent: 4463828 (1984-08-01), Anderson
patent: 4499967 (1985-02-01), Anderson
patent: 4549633 (1985-10-01), Merritt
patent: 4597471 (1986-07-01), Anderson
patent: 4747468 (1988-05-01), Greenway

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