172 the smaller contact area also avoids creating excessive friction between plunger 16 and rod 172 fig9 illustrates a 34 lost motion 34 push button 21 which is especially adapted for effecting minute reciprocations of rod 172 or rod 14 of fig1 on each actuation of push button 21 in the present embodiment rod extension 60 of rod 172 extends into a lost motion cavity 190 of push button 21 reaching short of push button top 70 and leaving a gap 34 g 34 from the free end 198 of rod extension 60 to the top 70 of push button 21 rod extension 60 is modified in the present embodiment to include a reduced diameter section 192 along its body between neck 48 of cylinder 12 and push button neck 74 of push button top 70 the free end of push button neck 74 terminates in tabs 194 which project into the reduced diameter section 192 and are normally in contact with the edges 196 of the reduced diameter section 192 in contrast to the embodiment of fig1 7 rod extension 60 is slidable within cavity 190 of push button 21 in operation inward actuation of push button 21 results in initial relative sliding between push button neck 74 and rod extension 60 during.