Liquid dispensing system and automatic selector therefor.

摘要

A reciprocable device comprising a reciprocable member (17) mounted for reciprocating movement within a chamber (15) and a valve system (43,47) for controlling the supply of fluid under pressure to the reciprocable member (17) to bring about reciprocation of such member. Bistable spring means are enabled by the reciprocable member (17) to operate the valve system (43,47) whereby at least some of the force for driving the valve system (43, 47) is obtained from the bistable spring means and not from the reciprocable member (17).