Patent GB-498469-A (GB)
Title: Improvements in or relating to starting and stopping mechanism of power driven machines
IPC: B30B15/28
Filed: 1937-07-05
Abstract: 498,469. Stopping and starting mechanism. BRITISH UNITED SHOE MACHINERY CO., Ltd., KEALL, F. B., and BROWN, S. July 5, 1937, No. 18584. [Class 80 (ii)] In a cutting-out press or like machine which is started by depressing a treadle 64, Fig. 2, so as to release a latch normally preventing engagement of a clutch, and which is stopped at the end of one revolution by the automatic disengagement of the clutch and application of a brake-band 55, a lever 104, Fig. 4, is so arranged that, when it is moved by the operator from the normal to a " safety " position, not only is actuation of the treadle ineffective to release the latch but also the clutch is incapable of being in an engaged condition. The application of the brake is effected both by a member 50 pivoted on the cross-head 30 and by a cam 32 on the press shaft 20, the cam being effective to maintain brake application if the press should overrun the desired stopping position. The treadle 64 is pivoted at 68 at the front of the press and is connected by a rod 74 to an arm 76 loose on a shaft 54 journalled at the rear. The clutch is controlled by a rod 82, Fig. 4, connected through a toggle device to a rod 80, Fig. 2, connected to an arm 78 fixed on the shaft 54, and the brake is operated by the shaft 54 through toggle levers 96 and 98, Fig. 3. The upper end of a link 36, Fig. 2, is connected to an arm 38 pivoted on the frame and pressed by a spring 40 so as to maintain a roller 34, carried by the link, in contact with the cam 32. The lower end of the link 36 is connected through a link 46 to an arm 52 fixed on the shaft 54, the link 46 having an abutment 48 co-operating with an abutment 49 on the member 50, which latter is urged clockwise by a spring 31. A bar 44 connected at one end to the arm 76 carries an abutment 56 co-operating with the upper end of the member 50, the bar being connected also by a slotted rod 42 to the arm 38. On depressing the treadle, the bar 44 is moved leftward to turn the member 50 so as to release the abutment 48. Thus, under the action of a spring, the clutch engages and the brake is released. During the subsequent movement of the press, the member 50 is released from the abutment 56 and turns clockwise so that on the upward stroke of the press the abutment 49 picks up the abutment 48 and turns the shaft 54 to disengage the clutch and apply the brake. The cam 32, however, also acts to lift the arm 52, so that brake application is maintained even if the press moves beyond the desired stopping position and in so doing causes the member 50 to be lowered. Through the rod 42, such further movement lifts the bar 44 so as to move the abutment 56 out of the range of the member 50, thus preventing re-starting of the press. The abutment 56 is, however, formed on a spring-loaded lever 58 pivoted on the bar 44. A rod 60, connected to the lever 58, may be pulled so as to bring the abutment 56 momentarily opposite the member 50, to enable the machine to be started. A finger 88, Fig. 3, is brought as the brake is applied into the path of a projection 90 on the brake drum 24 so as to act eventually as a positive stop if the brake fails. After such stoppage, the finger may be freed from the projection by operation of a bell-crank lever 92, 94, Fig. 3. The rod 82, Fig. 4, is connected at 102 to the rear end of the lever 104 provided at its front end with a handle 105. Near the rear end, the lever 104 is connected at 106 to the clutch lever 100 through a link 108. The lever 104 is, near the handle end, guided in a horizontal arcuate slide 110 secured to the frame. A horizontal drum 116 journalled above the slide has a spiral groove engaged by a pin 120 on the lever 104 so that the drum is rotated as the lever is moved across the slide. With the lever 104 in the position shown in Fig. 4, in which the word " Danger " is exposed on the drum, normal actuation of the clutch can occur, the lever being retained in this position by a pivoted catch 126 which can be released by pressure on a grip 130 pivoted on the lever. When so released, the lever is urged towards the other end of the slide by a spring 114. In this position, in which it is held by a spring- loaded pin 142 and in which the word " Safety " is exposed on the drum, engagement of the clutch cannot occur, the movement of the rod 82 being limited by co-operating stops 122 and 124. To move from " Safety " to " Danger " position, both hands of the operator are required, one to lift the pin 142 and the other to move the lever 104. The lever 104 is connected by a rod 144, bell-crank lever, and rod 148, Fig. 2, to the bar 44 so as to lift the latter and render it ineffective to trip the clutch when the lever 104 is in " Safety " position. Specifications 14413/11, 4833/13, [both in Class 80 (ii)], and 403,084 are referred to.