80 pin 76 will hold valve stem 60 and connected valve 50 against downward movement even if the water pressure in the shoe 24 is not sufficient for this purpose to open the valve 50 the lever 84 is pulled to the left in fig1 thereby retracting pin 76 from notch 78 valve stem 60 and connected valve 50 may then be moved downwards thereby moving the valve 50 to its opened position as soon as the notch 78 is below the pin 76 the lever 84 may be released whereupon the pin 76 will slide along the stem 60 downward movement of the stem 60 is limited by travel stop 70 which abuts plate 48 when the valve 50 is in its fully opened position to avoid interference between pin 76 and stop 70 stop 70 preferably has a radially extending slot not shown in alignment with the pin 76 it will thus be apparent that the means 74 is reliable for holding the stem 60 and connected valve 50 in the closed position also because the coil spring 80 is subjected to only slight compression upon downward movement of valve stem 60 spring 80 is not likely to lose its elasticity or break even after prolonged use to insure reliability of the means 74 pin 76 and lever 84 are preferably comprised.