said valve housing further having a stationary upper stop and a movable lower stop projecting outwardly from {TAIL ~ said front side} of said valve housing in the direction of said axle, said lower stop being angularly spaced from said upper stop and being adjustably mounted on said front side of {HEAD ~ said valve housing} so as to vary the angular distance between said upper and lower stops 
said valve housing further having a stationary upper stop and a movable lower stop projecting outwardly from { TAIL ~ said front side } of said valve housing in the direction of said axle , said lower stop being angularly spaced from said upper stop and being adjustably mounted on said front side of { HEAD ~ said valve housing } so as to vary the angular distance between said upper and lower stops
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