GB602968A - Improvements in or relating to control mechanism for hydraulic or other devices - Google Patents

Abstract

602,968. Toggle linkwork. JONES, P. H. Nov. 13, 1945, No. 30382. [Class 80 (iii)] [Also in Group XXIX] A snap-action toggle mechanism for controlling the reversal of movement of a member, e.g. a hydraulic ram, includes a lever 2 pivoted at 3 and having one end connected by a rod 1 to the ram, and the other end pivoted to a floating link 4. The latter is connected by a tension spring 5 to one arm 6 of a bell-crank lever, the other arm 7 of which is connected to a valve 9. The pivot of the bell-crank lever may be at 3. The valve 9 which controls the supply of pressure fluid to the ram is balanced hydraulically by a piston 12 below which a duct 14 leads to a casing 15 enclosing the linkwork and having a drainage opening 16. In the position shown, the valve 9 is held closed by the spring 5 so that pressure fluid passes through the duct 13 to move the ram. As the latter moves, the rod 1 will turn the lever 2 in an anti-clockwise direction. As soon as the pivot point of the links 2, 4 crosses the line of action of the spring 5, the latter swings the link 4 about the pivot point so that the lower end of the link 4 abuts the right-hand part of the casing 15. The spring thereupon acts on the bell-crank lever to move it clockwise and open the valve 9 rapidly and permit the ram to reverse its stroke under spring action. During such return stroke, the lever 2 is moved clockwise and a similar snap action takes place at the end of the stroke to close the valve 9. The ram mechanism may be applied to a hydraulic pipe pusher for forcing pipes under roadways and the like.