| 摘要 |
746,862. Hydraulic pit props. DOWTY HYDRAULIC UNITS, Ltd., [formerly DOWTY AUTO UNITS, Ltd.], and PRICE, W. R. Sept. 1, 1954 [Sept. 4, 1953], No. 24554/53. Class 20(2). [Also in Group XXIX] In a hydraulic pit prop a preset relief valve 35 is loaded by a spring 39 to seat upon a release valve in the form of a removable capsule 26 which is retained in an operative position in valve housing 21 by a cap 30 cooperating with a spring 29. To collapse the prop, the capsule 26 is lifted from a seat 28 in the valve housing 21, against the spring 29, by an externally operable cam 46. The loading of the relief valve is determined by shims placed between the spring 39 and one of its abutments. |
