Patent GB-1410759-A (GB)
Title: Rotary drum machines and safety devices therefor
IPC: B04B7/06
Filed: 1971-12-16
Abstract: 1410759 Machinery safety devices GENERAL MOTORS Ltd 7 Dec 1972 [16 Dec 1971] 58393/71 Heading F2J [Also in Division F4] The lid 4 of a rotary drum machine is prevented from opening while the drum 8 is rotating by a latch 40 whose release although initiated by a pedal 46 is controlled by a rotation-sensing device comprising a pair of levers pivoted together and to a contact member which is deflected by engaging a rotating boss 20 (Fig. 2), or drive belt 152 (Fig. 12), or the drive motor shaft or a drive pulley on that shaft, to prevent pivoting between the levers but which undeflected serves as a strut when the drum is stationary to permit such pivoting In Figs. 1, 2 and 7, the latch 40 is released by a rotation of a push-rod 32 having a crank 44 linked by rod 96 to a second lever 70 pivoted at 62 to a first lever 56 and also at 62 to a contact member 80 engageable with a rotatable boss 20 engageable by brake pads 28 on a pivoted brake plate 24. The first and second levers 56 and 70 are biased parallel by a spring 90, the first lever carrying a stop 64 for the second lever. The first lever 56 is pivoted at 54 to a fixed plate 52 and is biased by a spring 94 anticlockwise (Fig. 7), the lever 70 abutting a stop 92 (Figs. 5 and 6, not shown) on the lower edge (as seen in Fig. 7) of the fixed plate 52. A spring 88 biases the contact member 80 against a stop 68 on the first lever 56. Operation.-Closing the lid 4 against the spring hinge 6 cams the latch member 34 into engagement with the latch, and also depresses the push-rod 32 which pivots the brake plate 24 downwards to release the boss 20 and close a microswitch to energize the drum motor (not shown). Actuation of the pedal 46 pivots both levers 70 and 56 about fixed pivot 54, and the member 80 engages the rotating boss 20 and is deflected and the levers 70 and 56 continue to pivot without causing movement of rod 96. Actuation of pedal 46 also moves a pivoted latching finger 48 away from a stop surface 49, and allows the brake plate 24 to pivot upwards, the lid 4 being slightly raised by the push-rod 32 but still latched shut. A further actuation of the pedal 46 once the drum is stopped causes the member 80 to act as a strut (see Fig. 7) causing the second lever 70 to pivot about 62 and displace the link 96 so releasing the latch 40. In a modification, Figs. 9 and 10 (not shown), the first lever 56 engages the stop 92, and the link 98 is replaced by a spring-loaded lever (298). In another embodiment (Fig. 12), the contact member 178 is engageable with a belt 152 engaging a pulley 154 on the motor drive shaft 158. The pedal (not shown) is connected to a Bowden cable 192 which is connected to a first arm 188 of the second lever 176, whose second arm 190 is connected to a Bowden cable 194 which is connected to a latch push-rod. The sheath 172 of cable 194 is retained in an arm 166 of the first lever 160. One or more solenoids with a time switch may be used in place of the pedal and push-rod, such that one operation of a switch would stop the machine and ensure opening of the lid.