| 摘要 |
A mobile derrick includes a chassis frame and a mast frame rigidly mounted on the chassis frame. A mast is rigidly secured to the mast frame and extends upwardly therefrom for supporting a derrick at its upper end. A body is mounted over the chassis frame in a manner which permits it to be free from rigid connection with the mast so as to allow the mast, mast frame, and chassis frame to deflect independently of the body.
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