Tappet for the valve gear mechanism of an internal combustion engine

PCT No. PCT/EP97/03089 Sec. 371 Date Mar. 18, 1999 Sec. 102(e) Date Mar. 18, 1999 PCT Filed Jun. 13, 1997 PCT Pub. No. WO98/16726 PCT Pub. Date Apr. 23, 1998A tappet (1) comprises an annular section (2) which concentrically surrounds a circular section (5). The two sections (2, 5) can be loaded by cams (4, 7) of different lift and be coupled to each other when desired by radially displaceable sliders (11, 14). To avoid switching errors, the slider (11) extending in the annular section (2) can be selectively prevented from being displaced by a piston (26) which comprises a control edge (28) and is displaceable in the longitudinal direction of the tappet (1). For this purpose, the piston (26) cooperates with a groove (29) of a cam (4) starting from a second part ( beta ) of the base circle of the cam. During this part ( beta ) of the base circle, the piston (26) can be displaced by hydraulic medium pressure in cam direction into the groove (29) so that it extends with its control edge (28) in an annular groove (30 or 31) of the first slider (11) and thus locks this slider (11) out of its desired displacement phases.