The free travel of the pusher pistons is not more than 0.1 mm.
1 - pusher cylinder; 2 - groove; 3 - plunger; 4 - check valve; 5 - spring
The hydraulic tappets are self-adjusting and filled with oil. Spring 5 (pic. 3.9), located in the pushrod cylinder, and keeps the pushrod in constant contact with the camshaft. The force of this spring is lower than the force of the valve springs, which ensures linear movement of the valve.
check valve (4) prevents oil from being squeezed out when the camshaft cam acts on the pusher and when the oil pressure in the pusher cylinder exceeds the oil pressure in the engine lubrication system.