and to close inner cylindrical housing 24 the outer portion of spiral torsion spring 21 is fastened to inner cylindrical housing 24 by screw 26 fig4 and the inner end 28 of the torsion spring 21 is formed at a right angle spring axle 29 extends through the front aperture 30 of drum 11 with the front aperture 30 being concentric with respect to the drum spring axle 29 includes an end cap 31 at one end and an inwardly tapered annular flange 29a formed on its opposite end the spring axle is tubular with longitudinal slots 32 formed therein and with an internal shoulder 34 adjacent cap 31 when spring axle 29 is inserted through front aperture 30 the right angle end portion 28 of the torsion spring 21 is received in one of the slots 32 washer 35 is positioned over the inwardly protruding end of spring axle 29 and the central opening 36 of cap 25 is positioned about the inwardly protruding portion of spring axle 29 spring latch assembly 38 comprises latch 39 and coil compression spring 40 attached to the latch coil compression spring 40 is sized and shaped so as to be telescopically received in the longitudinal opening of spring axle 29 and the latch is also slid into the slots 32 with the wings 41 of the latch protruding out through the slot 32 rotor 44 is approximately disk shaped and is of a diameter slightly smaller than the inside diameter of drum 11 rotor 44 comprises a pair of spaced rotor plates 45 and 46 which.