GB528776A - Improvements in safety locking devices for the covers and lids of machine casings and pans - Google Patents

Abstract

528,776. Machinery guards. BEKEN, H. F., and TROUGHTON, E. R. May 15, 1939, No. 14427. [Class 80 (iv)] Relates to safety locking devices for machines having a tiltable mixing chamber or pan, and more particularly to the provision of locking means for the lids or covers of such chambers and pans which is so interconnected with the driving mechanism, e.g. for the rotating blades, that the machine cannot be started unless the lid is closed and the lid cannot be opened while the machine is working. The chamber or pan 4 is tiltable about trunnions 3 and has a cover or lid 5 hinged at 28. The machine is controlled by a rod 6 actuated by a handle 7 this rod being slidable in a bore in a block 8 across which can slide a shutter 9 with aperture 10. The rod cannot be moved to start the machine if the aperture 10 and bore 8 are not in register. The shutter 9 is connected to a rod 11 guided at 12 and having at its upper end a roller 13 engaging an arcuate groove 14 in an annular plate 15 which has a pair of diametrically opposite lugs 16 slotted to receive rollers 18 mounted on pins projecting from the chamber 4. The line of the lugs 16 is inclined at about 45 degrees to the rod 11. Connected to the plate 15 opposite the roller 13 is a rod 19 which is connected at its upper end to one arm 20 of a bell-crank lever 21, the other arm 23 of which is hooked and adapted to lock the cover 5. The lever 21 is mounted on a rod 24. As shown, the machine is at rest and the locking mechanism is set to release the cover 5. By throwing the lever 21 into this position the plate 15 was forced downwardly along an oblique path and the shutter 9 was. moved to bring the aperture 10 out of register with the bore 8 thus preventing actuation of the starting rod 6. To permit this rod to be actuated and the machine started, the lid must be closed and the lever 21 moved to lock it whereby the plate 15 and rod 11 are drawn upwardly to bring the aperture 10 and bore 8 in register. To ensure that the lever 21 can be thrown over only when the lid is closed, the lid has a plate 27 which, unless the lid is closed, obstructs a pawl 26 on the shaft 24. The machine may be stopped with the pan in any position and the lid opened and closed again, due to the loose roller and annular slot coupling.