Hydraulic tappets

The hydraulic tappets automatically cancel the valve clearance during engine operation, with the advantage of reducing:

• maintenance interventions
• engine noise.

OPERATION IN OPEN STAGE

When the camshaft cam acts on the cup 1 and consequently the piston 2, the oil trapped in the chamber 6, because the ball valve 4 closes, transmits the movement of the piston 2 directly to the sleeve 3 and so to the valve. During this

stage, because of the high pressure to which it is subjected, some of the oil in the chamber 6 leaks through the tiny gap between the piston 2 and sleeve 3.

OPERATION IN CLOSED STAGE

While the valve is closed, so that the tappet, pushed by the action of the spring 5, follows the profile of the cam, a vacuum is created inside the chamber 6 which causes the ball valve 4 to open, allowing oil to enter. The oil entering the

chamber 6 replaces the oil which leaked out previously while the valve was open.