GB1079860A - A control system for a pluratlity of hydraulically operable elements - Google Patents

Abstract

1,079,860. Advancing mine conveyers. COAL INDUSTRY (PATENTS) Ltd. Dec. 22, 1964 [Dec. 24, 1963], No. 50965/63. Heading F1P. A hydraulic system for controlling the supply and discharge of fluid to double-acting rams 2-12 arranged to advance a conveyer 1 towards a mine face, comprises.a valve 13 associated with each ram (only one of which is shown) each operable independently to cause extension or retraction of its associated ram, and group control valves 15-20 selectively operable to cause extension of a group of rams. As shown, each group has four rams 4-7, 7-10 &c., each ram being connected through a non-return valve 14 or non-return valves 22, 23 to a hose C in which are disposed the group control valves 15-20. The group control valves are arranged symmetrically in pairs to enable the conveyer to be advanced from either end. To advance the conveyer from left to right, group control valve 16 is opened, whereby the section of the hose C between valves 16 and 17 is pressurized from a branch line 21 connected to a pressure main P and hence rams 4-7 commence to advance the conveyer. After the rams 4, 5 and 6 have fully extended valve 16 is closed and their associated valves 13 are operated to cause retraction of the rams and consequential advance of any roof supports secured thereto. The completion of the extension of the ram 7 and the initiation of the extension of the rams 8, 9 and 10 is accomplished by operation of the group control valve 18. In a second embodiment Fig. 3 (not shown) the rams are connected through non-return valves across a pair of hoses and the group control valves are arranged so that they pressurize four rams at a time, two of which have previously been pressurized by operation of the preceding group control valve.