| 摘要 |
A pump jack arrangement for traveling up and down a pole including a frame member upper and lower shackle members supported by the frame member. A pump arm and a support arm are provided for supporting weights. The pump arm is utilized for causing the shackle members to alternately grip the pole. The non-gripping shackle member is stepped upwardly along the pole. The upper and lower shackles include pivotally interconnected yoke members and linkage members which are pivotally connected utilizing the rear gripping rod of the yoke member itself as the pivot. The pump jack is formed of U-shaped channels in order to provide additional supports. The support arms themselves also comprise opposingly interfitted U-shaped channels to provide a slidable support arm. A guard plate is provided over the front gripping rod of the upper shackle.
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