(1) The barrier valve furthermore has a tappet , which engages the support body and is movable relative to the armature and carries a closing body of a seat valve.(2) Very small roller cam followers are installed in the cylinder head to operate the valves instead of the conventional bucket-type tappets , and here friction is cut by about 70 per cent.(3) Contact between the cams and the tappets in the valve train span the mixed and boundary regions.(4) The real breakthrough in lifter design for street and moderate competition applications was the marriage of roller tappets with hydraulic lifters.(5) The 16-valve has twin, chain-driven, overhead camshafts and hydraulic tappets , while the 8-valve format uses a single camshaft.
