Rajsircar said:
These hydraulic lifters are not lifters. They are automatic lash adjusters
Semantics. Setting aside the part about being adjustable or not because
that's a separate issue, lash adjusters do the same thing as hydraulic
lifters, but are just in a different position in the lever (rocker)
arrangement than traditional lifters.
"Lifters" are called such because they are between the cam, rocker, or
push rod (depending on engine design) and the end of the valve stem -
i.e., they act directly on the valve - they lift it. The "lash
adjusters" are, typically, at the fulcrum end of a rocker, with the cam
pushing the middle of the rocker, and the valve stem being pushed by the
opposite end of the rocker, and therefore are not directly "lifting" the
valve.
If I understand correctly, all hydraulic lifters are lash adjusters, but
not all lash adjusters are lifters (i.e., the ones at the other end of a
rocker from the end in contact with the valve stem are not directly
lifting the valve, though without them, the valve would not get lifted
by the other end of the rocker).
The non-in-line lash adjuster (as opposed to in-line lifter) is a nice
concept - it gets the mass out of the valve motion (less tendency to
float at high rpm) while still allowing hydraulic cushioning.
People (including mechanics and engineers - some knowingly, some out of
ignorance) often refer to the lash adjusters as lifters, though
technically you are correct - they are not lifters. And most people who
do know the difference don't worry about the distinction because in most
discussions, the difference doesn't matter. In a discussion in which it
would matter, then it would be necessary to point out the technicality.
Bill Putney
(to reply by e-mail, replace the last letter of the alphabet in my
address with "x")
