| 摘要 |
Powered mine support has a hydraulic prop between roof and floor bars which can swing from a position pointing to the goaf into a position where the prop head faces the coal, taking the roofbar with it, with conventional shifting rams fitted. A back-up and forepoling cylinder (18) between prop (9) and floor bar (6) or connected support bearing (6', 16) swivels the prop over relative to the floor bar and thus places the forward bar (18) in the forepoled position. - The cylinder (18) can be fitted with a metering device for stroke adjustments. The cylinder can engage the prop at adjustable positions along the prop, possibly using an engagement sleeve (21) which alides along the prop for this purpose. The unit can be fitted with a standard type of waste shield. The shield member (11, 12) can be linked to each other and floor and roofbars.
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