Patent GB-1212211-A (GB)
Title: Rotary-drum machines
Inventor: HOPKINS REGINALD THOMAS
IPC: B04B7/06
Filed: 1967-11-02
Abstract: 1,212,211. Machinery safety devices; disc brakes. GENERAL MOTORS Ltd. 26 Sept., 1968 [2 Nov., 1967], No. 49789/67. Headings F2E and F2J. [Also in Division F4] . A spin dryer or other centrifugal extraction machine having a rotary drum provided with a braking device, and a latch to hold closed a lid to cover the drum, cannot be started until the lid is latched shut and, when the brake is applied to stop the drum, the latch cannot release the lid until braking has ceased. In Fig. 1, a spin dryer drum 5 is mounted on a hollow shaft 7 rotatably supported on a post 9 fixed in the dryer casing 1. A brake ring 15 having friction pads 25 and peripheral lugs 29, 31, normally rotates with the shaft 7, being gripped between the shaft 7 end face 17 and a spring-urged plate 19 rotatable with the shaft. The casing lid 3, urged open by a torsion spring 4, has a stud 33 with barbs 35, 37 engageable by a slidable latch plate 39 urged leftwards (Fig. 1) by a spring 43. When the lid is fully closed, as shown, the barb 35 engages the latch plate and the stud 33 holds a rotatable and axially movable rod 49 depressed against the thrust of a spring 53, a collar 55 on the rod closing a switch 69 in the circuit of a drive motor (not shown) for the drum. When the latch button 41 is pushed, the spring 53 moves the lid 3 and the rod 49 upwards until the barb 37 engages the latch plate, so that the switch 69 opens to deenergize the motor and an end 51 of the rod 49 stands in the path of lugs 29, 31 to hold the brake ring 15. Brake torque rotates the rod 49, against a spring 61, from a stop 63 to a stop 65 (Fig. 3) to engage a cam 59 on the rod 49 with an arm 45 of the latch plate 39 to prevent release of the stud 33. When the drum stops, brake torque falls to zero and spring 61 rotates the rod 49 back to stop 63, causing cam 59 to allow spring 43 to move the latch plate to release the stud 33. In Fig. 5, a spin dryer drum 113A is mounted on the shaft 114 of a motor 113B on resilient mounts 113C. A brake disc 115 on the motor shaft passes at one side between brake pads 1120 on caliper arms 121, 122 which are pivoted at 120 to a longitudinally slidable plate 117, and are urged apart by a spring 123. Their free ends are connected together by a toggle linkage 124 the knee of which is anchored by a tension spring 125. A stud 137 on the lid has barbs 138, 139 engageable in a slot 136 of a pivotal latch plate 236 urged clockwise (Fig. 9) by a spring 238. When the lid is closed, the barb 138 engages the latch plate and the stud 137 holds a rotatable and axially movable rod 127 depressed against the thrust of a spring 128, a collar 250 on the rod closing a switch 252 in the motor 113B circuit. When a brake pedal 132B is actuated, it rotates the rod 127 against a tension spring 133 so that an arm 134 on the rod pivots the latch plate 236 to release the barb 138, the rod moving upwards until the barb 139 engages the latch plate. The motor switch 252 is opened by the upward movement. Also the rotation of the rod 127 acts via a Bowden cable 150 to move the plate 117 leftwards (Fig. 5) so that the caliper arms 121, 122 are pulled together by the toggle for brake application. Brake torque reaction moves the plate 117 further left, giving a stronger braking and holding the rod 127 rotated. When the drum stops, brake torque falls to zero, and spring 133 rotates the rod 127 back till the spring 238 has pivoted the latch plate 236 sufficiently to release the stud 137.