| 摘要 |
An extendible jack stand for a jacking system which includes a wheeled hydraulic power unit having an operating handle, and at least two extendible jack stands which are identical. Each jack stand is adapted to rest upon the ground, and the power unit can be wheeled into (or out of) engagement with the jack stand. When engaged with a jack stand the power unit is capable of extending (or raising) the jack stand; a ratchet on the jack stand then locks it in its extended position. A manual control on the power unit is coupled to the jack stand (when the two units are interengaged) for releasing the ratchet, so that the power unit can then lower the jack stand to its retracted position.
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