| 摘要 |
A lightweight jack for supporting the roof of a mine until permanent supports are in place. The jack is carried by a roof bolter or similar mining equipment on the end of a support arm. A hinge box is mounted on the sidewall of the roof bolter and one end of the arm is hingedly received therein. A support plate extends from the sidewall outwardly below the arm. The support plate carries at the far end a U-shaped bracket with a spring inside the bracket. The support arm rests on the spring when the jack is not extended. A swivel arm is received inside the support arm and held from turning by a swivel pin. When the pin is removed, the swivel arm and jack may be turned sideways for easy manuevering by the roof bolter.
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