870,731. Overhead conveyers. TELEFLEX PRODUCTS Ltd. Dec. 16, 1958 [April 9, 1958], No. 11315/58. Class 104 (2). In a conveyer in which trolleys provided with running and guiding wheels are propelled along a track of cruciform cross-section by dogs depending from a chain also provided with running and guiding wheels running on a track of cruciform cross-section each trolley has three cam followers located above the trolley track level and all projecting on the same side of the trolley at right-angles to the direction of travel; the first cam follower acts as a stop to hold the trolley from movement and co-operates with a vertically movable camplate mounted on the trolley track which cam-plate in its lowest position is cleared by the stop and in its highest position engages the stop; the second cam follower, in the normal lower position it can occupy, is located at a lower level than the first cam follower and co-operates with a vertically movable camplate so that it is only operated when the camplate is in its upper position, and further is mounted on a lever pivoted to the trolley and connected to a stop carried by the trolley which stop, in the normal lower position of the second cam follower, is held by the lever in an upper position to be engaged by the depending dog on the conveyer chain and which, in the lower position is withdrawn from driving engagement with the driving dog; and the third cam follower, which projects to a greater extent and is located towards the rear of the trolley and at a higher level than the normal levels of the other two cam followers, cooperates with tilting plates, pivoted about horizontal pivots fixed in relation to the tracks and in a vertical plane parallel to the vertical plane containing the depending driving dogs, which plates control the setting of the vertically movable cams located at the rear of the trolley. In the arrangement shown in Figs. 4 and 5, each trolley has a vertical load-carrying plate 24 on which are mounted track-running and guiding wheels 22, 23 and carries an upwardly spring- biased slide 28 provided at its upper end with a stop 30 which in its uppermost position cooperates with a dog 20 depending from an overhead chain for pushing the trolley along the trolley track in the direction of arrow 31. To the right of the slide 28 a plate, pivoted at 32, is provided with two arms 33, 34, the arm 33 of which is slotted and engages a pin 35 projecting from the slide 28 and the other arm 34 of which carries a freely-rotatable roller 36 and has its downward movement limited by a stop 37. A two-arm lever, provided with a stop 38 at one end and having its downward movement at the other end limited by a stop 39, is also pivoted at 32. This lever is freely pivoted to allow the dog 20 to depress the stop 38 when moving into drivng contact with the stop 30 and engages the pin 20 when the trolley is moving down an incline. To the left of the slide 28 a plate 40, pivoted at 41, carries a laterally projecting roller 42 arranged at a higher level than the roller 36. The downward pivoting movement of the plate 40 is limited by one of the pins 27 serving as guides for the slide 28. To the right of the slide 28 there is a roller 43 which projects to a much greater extent laterally than the rollers 36, 42, and is arranged at a higher level. In the arrangement shown in Figs. 5 and 7, the upper part 44 of the trolley track has mounted on the upper outer surface thereof an L-section member 45 having two shaped and parallel slots 46 therein. A combined vertically movable stop and cam-plate 48, having rollers which engage in the slots 46, is mounted between a part 47 of the trolley track and the rear of the L-section member 45. The upper surface of the camplate 48 has a rising inclined cam 52, a level surface 53, a downwardly-inclined cam 54 and a horizontal surface 55 terminating in a hook 51. A tilting plate 56, pivoted at 57, has a slotted arm 59 which engages a pin 60 secured to the lower left-hand edge of the stop and camplate 48. The rear face of the tilting plate 56 has cam-shaped surfaces 62, 63 which cooperate with the roller 43. The first camplate 48, Fig. 8, is not operated by a tilting plate 56 but by any suitable mechanical, electrical or pneumatic mechanism which can raise the first stop 48 to stop an oncoming trolley so as to hold the trolley on the track and to cause the trolley to raise the next plate 48 and to stop the following trolley which in turn stops the succeeding trolley. An arrangement, Fig. 8, for raising or lowering the first cam 48 comprises two solenoids 65, 66 and each core of each of the solenoids 65, 66 has a link 67 pivoted thereto the other ends of the links being pivoted together at 68. Pivoted at 68 is an arm 69 which is pivoted to a fixed part 70. When the solenoid 65 is operated the end of the arm 69 remote from the part 70 is raised and the cam-plate 48 is lowered through the intermediary of a pivoted rocking plate 72 connected to the arm 69 through a pin and slot joint 71 and to the plate 48 through a pin and slot joint 73. The apparatus operates as follows. The solenoid 66, Fig. 8, is operated to raise the first cam-plate 48 and the roller 36 of the first trolley rides on to the hoiizontal portion 53 of the first cam-plate 48 to move the slide 28 of the trolley downwards out of driving contact with the driving dog 20, and the trolley is stopped by the roller 42 engaging the hook 51 of the first cam-plate 48. The roller 43 of the first trolley engages the cam 62 of the first tilting plate 56, Fig. 7, this plate 56 is then tilted and in so doing raises a second camplate 48 to stop the second trolley by means of the roller 42 engaging the hook 51. The roller 36 of the second trolley rides on to the horizontal portion 53 of the second cam-plate 48 to lower the slide 28 of the second trolley out of engagement with its driving dog 20 and the roller 43 of this trolley tilts the plate 56 to operate the succeeding cam-plate 48 to stop the succeeding trolley. To release the trolleys the first cam-plate 48 is lowered by operating the solenoid 65 and the first trolley is moved forward by a driving dog 20, and in so doing its roller 43, Fig. 7, engages the cam 63 to tilt the plate 56 in order to lower the second camplate 48. A switch tongue 85, Fig. 9, driven by an electric motor 77 through a reduction gear 79, a chain 81 and a friction clutch is provided at the junction between the main conveyer track and the storage conveyer track. The trolleys are moved over the " dead " zone, Fig. 11, between the main and storage overhead driving chain sections or vice versa from one to the other of positions 101 by means of dogs 112 on an endless driven chain 110 projecting through the side wall of the track and engaging the plate 24 of a trolley. The whole system can be controlled electrically from a central operating point.