GB390578A - Improvements in or relating to automatic latches on safety covers or guards and associated protective means for centrifugal apparatus - Google Patents

Abstract

390,578. Machinery guards. MANLOVE, ALLIOTT, & CO., Ltd., Bloomsgrove Works, Nottingham, ALLIOTT, E. A., Rostherne, Hervines Road, Amersham, Buckinghamshire, and WARD, H., 9, Julian Road, West Bridgford, Nottingham. Dec. 24, 1931, No. 35731. [Class 80 (iv).] A guarding device, such as the cover of a centrifugal drier, is provided with latching mechanism such that if the moving part to be guarded is in motion the guard cannot be moved from operative position. The cover C is hinged on the same spindle 6 as a crank arm 1 which protrudes into a casing 2 containing a looking bar 9, 10 pivoted at 11. The bar is spring-pressed in a counter-clockwise direction and supports a swinging pawl 12 by means of a pin 17. The bar 10 and pawl are formed with cheeks 15, 14 respectively. A slowmotion knob 24 and plunger 22 are provided for depressing the lever 10. If this is done while the basket 4 of the drier is in motion, when the foot 16 of the pawl touches the basket it is swung to one side so that the cheek 14 obstructs the cheek 15 in its descent so that the descent of the lever 10 is checked. The arm 9 is normally in the path of a projection on the crank and is insufficiently withdrawn unless the basket is at rest. The cover cannot be opened, therefore. If the machine is electrically driven a switch 30 is fitted, and connected as shown to the end of the lever 10. When the lever 10 is pushed down the contact 30a is broken and a solenoid holding a starting handle in " on "-position is de-energized; when the contact 30b is made the handle is looked in "off "-position. A sliding bolt 32 may be provided to work in conjunction with the source of power and so provide an additional safeguard. The bolt may, for example, be connected to belt-shifting gear, to the controlling valve of a hydraulic motor, or to the switch of an electric motor. In the device shown in Fig. 9, the bolt 32 has a neck 37 adapted to be engaged by a slot in the lever 9, and is connected by a Bowden wire with a cam 39 adapted to lock the driving control against operation. The bolt 32 may be employed to control a brake, Fig. 12, being withdrawn against a spring 46 by a cable having a lostmotion connection at 47 with a lever 48 held in " on " position by a catch 49. The brake is preferably self-locking in the " on " position and arranged so that it cannot be worked simultaneously with the guard.