and a pin 45 mounted in such housing pin 45 limits the counter clockwise movement of cam lever 42 and retains the valve actuating lever 40 in its locked and cocked position the end portion of cam lever 42 opposite the end portion that receives the pivot pin 43 is enlarged to define a head end portion which head end portion is recessed to receive a roller 23 which facilitates its caming action on lever 40 such head end portion of lever 42 has a bifurcated end 42 39 fig5 which receives the enlarged end portion of a lanyard in the form of a pull chain or cable 46 which cable 46 extends out through the slot of the bifurcated end 42 39 and through an opening 47 in trigger housing 29 and provides the means for actuating the trigger mechanism for spool valve 33 the lanyard may thus be detached from the cam lever 42 as the lanyard or cable 46 is pulled downwardly as viewed in fig1 3 the enlarged bore portion 25 of central bore 20 in hub portion 17 receives only a portion of the one stepped cylindrical end of trigger housing 29 to thus define a low pressure chamber 48 in its cooperation with.