Patent GB-296243-A (GB)
Title: Improvements in or relating to means for controlling cyclic operated plant and apparatus
IPC: C10J3/24
Filed: 1927-12-30
Abstract: 296,243. Tully, Sons & Co., Ltd., and Redon, L. de. Dec. 30, 1927. Producers. - In water-gas plant in which the valves or other control members are periodically actuated during a cycle of operations, a shaft carrying cams, acting positively in both directions of stroke is rotated at intervals in one or both directions during the cycle by a continuously-oscillating member carrying a pawl coacting with a toothed or notched wheel, its periods of engagement therewith being controlled by a mask operated by a timing-wheel in geared connection with the oscillating member. The cam shaft 4 carries a number of cams 25 having facial grooves 26 wherein rollers 27 carried by levers 28 travel, imparting positive actuation in both directions to main control valves &c. through links &c. 29, the cams tending to remain at rest in the position shown. The shaft is rotated at determined intervals by an oscillating arm 7 driven by a constantly-rotating shaft 1 through an adjustable throw-crank 5 and an adjustable rod 6, the arm 7 carrying a pawl 17 which engages a toothed or notched wheel 22 on the shaft when allowed to do so by a mask-arm 18 pivoted at 19 and coupled to an arm 20 pulled by a spring 21 so that the mask normally tends to prevent engagement of the pawl. The mask-arm 18 is coupled by a rod 24 to a bell-crank 23, the nose of which rides on the periphery of a timing-wheel 15 having projections 16 corresponding in number and spacing to the operations required in a complete cycle, the mask being depressed to allow engagement of the pawl each time the nose of the bell-crank rides over a projection 16. The timing-shaft 3 is driven from the primary shaft 1 through a cam 12 acting on a counterweighted lever 9 carrying a pawl 8 engaging a ratchet wheel 14 preferably of the form composing a pair of discs with staggered teeth halving the pitch. The cam discs 12 come into action as the arm 7 reaches either limit of its oscillation. The shaft 4 may be rotated step by step in one direction or may be reversed at intervals according to the arrangement of the projections 16 on the timing-wheel.. The timing-shaft 3 may carry additional cams or fingers for operating minor valves, switches, or governors to regulate speed &c. To lock the shaft 4 when stationary, a notch 30 or a projection on the mask 18 may be provided to engage respectively projections 31 or notches in the wheel 22. To stop the working of the plant in the event of failure of the air-blast supply, a second mask on the opposite side of the wheel 22 is carried by a bell-crank 36 mounted on the fulcrum 19 and is normally kept lowered out of action by the pressure of the blast supply acting through a pipe 32<a> on a piston or diaphragm 33 connected by a link 35 to the bell-crank arm 36, a spring 34 forcing the piston down in the event of failure of the supply pressure. In these circumstances, stoppage at a predetermined stage in the cycle of operations is obtained by engagement of a projection 39 on the end of the arm 36 with the inner face of an annular flange 38 on the timing-wheel 15, which holds the arm 36 up until, in its rotation, a gap 38a in the flange comes into position below the projection 39 and allows the arm to fall.