GB988786A - Improvements in mixers, for instance in concrete mixers - Google Patents

Abstract

988,786. Concrete mixers. P. AUGUST. Sept. 3, 1962, No. 33677/62. Heading B1C. [Also in Division G1] A concrete mixer of the type having a non- rotatable horizontal drum which has rotary mixing devices therein and is movable from a lower, charging position to an upper, discharging position is combined with a similar mixer for pre-mixing the dry solid materials. As shown in Fig. 1 the main mixer A has a drum 1 raised and lowered by a reversible motor (not depicted), winch 12 and cables 13 along inclined guides 9, 10 which tilt the drum in the uppermost position to discharge it through the shoot 7 into the hopper 11. The drum 1 has rotatable mixing devices continuously driven by an independent motor 5, and means (not depicted) for supplying water in metered quantities. The pre-mixer B has a similar drum 24 carried by freely rotatable rollers 26 on guides 30 and hoisted and lowered by a reversible pole-changing motor 39 which rotates the shaft 41 and rope drums 42, 43 fixed thereon, the rope 44 thereby rotating the pulleys 27 and thus the mixing devices in the drum 24 during the upward and downward motion of the latter. In operation the main mixing drum 1 closes a switch in its downward movement to start motor 39 so that the drum 24 reaches the top and discharges as the drum 1 reaches the bottom ; water having been first supplied to the drum 1, which is raised and lowered at greater speed than the drum 24 so that both cycles take the same time. The mixing device of the drum 1 (see Fig. 2) comprises a screw 15 and detachable paddles 14, 14a; the paddles 14 are inclined to convey in the opposite direction to the screw, while the three paddles 14a convey in the same direction as the screw to relieve pressure on the end walls 17. The mixing device of the pre-mixing drum 24, Fig. 4, consists of semicircular bands 45 having leading ends terminating in replaceable scrapers 48; the bands 45 are eccentric to the axis of the drum (see Fig: 6, not shown) and may be inclined to the axis of rotation (see Fig. 5, not shown). The walls of the drum 1 are made in replaceable sections. The lower portions 30a of the guide rails 30 are mounted by links 32 for oscillatory movement and are connected to a weighing device 33, which controls the motor 39 so that the drum 24 cannot be raised until it contains the desired weight.