Free travel of piston pushers is no 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 (Fig. 3.9) is located in the tappet cylinder and maintains the tappet 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.
The check valve (4) prevents oil from being squeezed out when the camshaft cam impacts the tappet and when the oil pressure in the tappet cylinder exceeds the oil pressure in the engine lubrication system.