When a set of Hydraulic Elevators are used, then a hydraulic supply from a directional control valve is required.

当使用一套液压提升集时，那么一个提供液压动力的方向控制阀是必需的。

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Configuration manual hydraulic device, can be in power failure or no power supply place as usual lifting.

配置手动液压装置，可在停电或无电源场所照常进行升降工作。

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An assembly of components and controls necessary to provide a hydraulic power supply.

提供液压动力源所需的部件和控制阀的组合。

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Concerns also have been raised about the possibility that hydraulic fracturing could contaminate the aquifers that supply drinking water.

WSJ: Daniel Yergin on the Shale Gas Revolution: Stepping on the Gas

The wider use of horizontal drilling and hydraulic fracturing, or fracking, has unleashed a vast supply of natural gas from the shale-rock formations across the U.S., forcing down domestic prices, cutting the need for overseas imports and making gas-exporting nations in Africa, Latin America and the Caribbean a less important piece in the U.S. energy puzzle.

WSJ: China's Xi Comes Calling on Americas

Hydraulic fracturing, or fracking, is under widespread development in the United States, fueling a natural gas supply boom, with an EPA review of its environmental safety underway.

FORBES: European Gas Giant Backs French Fear Of Fracking