GB540255A - Improvements relating to safety devices for use with printing platens - Google Patents

Abstract

540,255. Machinery safety devices. PHILLIPS, B. E. April 15, 1940, No. 6752. [Classes 80 (ii) and 80 (iv)] A platen printing press has a guard frame a pivoted at f to supports e and provided with a horizontal bar b arranged in close proximity to the outer edge of a platen c which moves towards and away from the type-carrying platen d, the guard being maintained in a normally vertical position by stops g. Journalled in the supports e is a driving shaft i which at one end carries fast and loose pulleys j, k and a gear wheel p adapted to be driven by the shaft by a dog clutch q, the wheel being slidable to engage and disengage the clutch. The other side of the gear wheel has a cylindrical extension s having a groove t engaged by rollers on an arm v of a lever pivoted to a starting rod 8. To arrest the motion after the clutch is disengaged, a brake w is provided comprising an axially movable bush w<SP>1</SP>, Fig. 3, and a split ring w<SP>2</SP> adapted to be contracted on the bush, the latter being provided with projections y which engage recesses z in the extension s. The ring is contractible by a pair of cams mounted respectively on an arm 4 and one of a pair of lugs 6 on the ring w<SP>2</SP> through which lugs a spindle 5 carrying the arms passes. The arm 4 has a lost-motion connection 14, 15 with the rod 8 with which engages an adjustable abutment 9 on the other arm of the lever v, the arrangement being such that the clutch is first disengaged and then the brake applied, the arm v being ultimately moved against the action of its loading spring 10. At its other end, the rod 8 is pivoted to an arm 16 on a shaft 17 on which is freely mounted a boss 31, Fig. 2, having a lost-motion connection with a boss 34 keyed to the shaft, the boss 31 carrying arms 18, 19. The arm 18 is loaded by a spring 20 or a weight tending to move the rod 8 to disengage the clutch and apply the brake and the arm 19 carries an adjustable stop 21 adpated normally to engage another adjustable stop 22 formed by an arm 23 pivoted to the guard frame at one end and connected at the other end by a link 24 to an arm h on the guard frame. The shaft 17 also has secured to it an arm 25 for actuating the belt-shifting fork n, and an arm 26 connected to a brake shoe 28 for the flywheel 30. Should the operator's hand come between the platen c and the guard rail b, the guard rail is moved and the stop 22 is moved clear of the stop 21 so that the spring 20 or weight moves the rod 8 to disengage the clutch and apply the brakes w and 28 and, at the same time, move the belt on to the loose pulley. The mechanism is re-set by a handle 35.