HYDRAULIC VALVE LIFTER .

All about engine/ the all parts related to the combustion chamber could be spread by the heat generated the engine. And for that the valve system could be band. By touching valve system rocker arm and then pushrod.so there the nesecary to keep clearance as valve clearance and taped clearance. And valve lash .and always have to chack them
And at the same time there is a sound generation in it. So keeping all this in mind,the use of HYDRAULIC VALVE LIFTER started to be done.therefore there no need to keep clearance.
And the sound of the taped also decreased.and the oil remains full in the working chamber of HYDRAULIC VALVE LIFTER, and if there is an expression then the oil gets Buried and the secound parts has no affected, and this does work in (0) clearance . Some engine does use electro hydraulic valve operated lifter, so there are an control of e.c.m.