Patent GB-589092-A (GB)
Title: Control mechanism for concrete mixers
IPC: B28C7/02
Filed: 1945-02-06
Abstract: 589,092. Mixing-machines. McMILLAN, A. Feb. 6, 1945, No. 3021. [Class 86] In a concrete mixing-machine in which a discharge chute or loading skip is movable by a power driven shaft through a clutch connection a follower is movable by a manually operable control lever into or out of the path of a cam carried by the shaft to be actuated by the cam to engage or disengage the clutch. The discharge chute may be retained in an inoperative position during the mixing period by an interlock between the chute actuating mechanism and a batch meter which is released slightly in advance of the end of the mixing period. The chute 16, pivotally mounted on a shaft 17 on a frame 10 is swung from its inoperative position shown in Fig. 1 to a reversely inclined operative position partially within the drum 12, by a power operated device 25 having a crank arm 24 connected through a link 23, a bell crank lever 22, and a link 21 to an arm 20 carried by the shaft 17. The device 25 is driven from a countershaft 15 by a chain and sprocket drive 26 through a clutch operated by a lever 27, against which bears a rod 40, Fig. 5, pivotally connected to an arm 37 of a lever 35. The latter is rotatably journalled on a pin 34 of a crank arm 33 carried on rockshaft rotatably mounted on the frame 10. To operate the discharging mechanism a control lever 47 is moved to the dotted line position, Fig. 5, and actuates the rock shaft through an arm 46, a cable 51 in a flexible sheath 52, and an arm 45, to bring a roller 38 carried by a second arm 36 of the lever 35 into contact with a rotating cam 39 on the countershaft 15. The cam 39 causes the lever 35 to pivot about the pin 34 to actuate the clutch lever 27 through the rod 40. The batch meter comprises a power driven shaft 60 which carries a disc 61 having a recess 62, and the meter is started by a lever 65 which removes from the recess 62 a dog 66 carried by a shaft 64. An arm 74 of a bell crank lever pivotedly mounted on a shaft 72 carries a roller 75 which bears against a cam 70 carried by the shaft 60, and the other arm 76 is connected to a wire 78 surrounded by a sheath 79. During the mixing period the end 78<SP>1</SP> of the wire 78 protrudes into the path of the arm 46 to prevent operation of the lever 47. A short time before the batch meter stops a projection 71 on the cam 70 rocks the crank 72 to withdraw the end 78<SP>1</SP> from the lever 46, so that the operator may commence the operation of the discharge chute mechanism. The loading skip 116, Fig. 7, may be raised and lowered by cables 118 passing over sheaves 119 and wound around drums 120. The latter may be rotated by a wheel 122 upon which is wound a cable 123 which passes to a winding drum 124 loosely mounted on the shaft 15 and adapted to be connected thereto by a friction clutch 125 having a shifting collar 126. The clutch is engaged by a hand lever 157 which actuates a sheathed cable 132 to rotate a crank lever 148, Fig. 9, linked to a sliding block 134 which pivotally supports the end of a lever 136. A roller 144 carried by the lever 136 is drawn into contact with a cam 143 rigid with the rotating shaft 15, and the lever 136 is caused to pivot about the block 134 to actuate linkage 138, 140 to move the collar 126 to engage the clutch 125. When the skip reaches its discharge position the clutch may be disengaged by automatic mechanism (not shown).