GB564507A - Improvements in or relating to valve tappet constructions - Google Patents

Abstract

564,507. Valve tappets. EATON MANUFACTURING CO. Oct. 28, 1942, No. 15131. Convention date, July 24, 1941. [Classes 7 (v) and 7 (vi)] A valve tappet for use in internal-combustion engines gives zero clearance between tappet and valve during normal operation of the engine, but has means to effect a predetermined tappet clearance to cause substantial reduction in valve lift, particularly to facilitate starting and idling. The tappet comprises a body 4 which receives a cylindrical shouldered sleeve 10 having a reduced lower portion which contains a ball valve assembly 14. The lower part of the body 4 accommodates a piston 22 urged upwardly by a spring 23 and carrying a pin 24 which when moved upwardly unseats the ball 14. The sleeve 10 encloses a plunger 12 urged upwardly against the valve stem by a spring so that no clearance exists between the tappet and the valve stem. In normal running, while the valve is opening, oil below the plunger 12 is trapped, thus affording in effect a rigid tappet. Loss of fluid past the plunger is compensated by flow of fluid past a valve 20 to the space below the sleeve 10. For starting, the valve 20 is moved either manually or automatically to the Fig. 3 position, wherein pressure fluid can escape from the space below sleeve 10, whereupon the piston 22 is moved upwardly by its spring and the pin 24 unseats the ball valve. This allows the piston 12 to fall under load to Fig. 3 position and so reduces the valve lift but allows the engine to function on a modified timing. As soon as the valve 20 is restored to the Fig. 1 position, pressure fluid is readmitted to operate piston 22 and normal operation is resumed. Specification 466,161 is referred to.