The invention relates to a tappet comprising:
- a housing with a blind bore and with a shelf groove arranged on the inner wall of the bore;
- a main body slidably arranged in the bore of the housing, wherein the main body comprises a first shoulder;
- a secondary body telescopicly arranged to the main body and having a second shoulder;
- spring means arranged between the first shoulder and the second shoulder;
- locking means extendable from the main body for cooperation with the shelf groove.
