Patent GB-403885-A (GB)
Title: Improvements in hoisting apparatus
IPC: B66D3/14
Filed: 1933-06-06
Abstract: 403,885. Hoists. COFFING, F. W., 101, South Crawford Street, Danville, Illinois, U.S.A. June 6, 1933, No. 16239. [Class 78 (v).] In a hoist in which the load-supporting chain passes over a sprocket engaged by a sustaining pawl and a ratchet on the same shaft as the sprocket is engaged by an actuating pawl, means is provided which has limited rotary movement relative to the shaft and is associated with means co-operating with the ratchet engaging pawl to permit predetermined operation of the shaft. The chain 18, Fig. 1, passes over a sprocket 17 which is integral with a shaft 16 and is engaged by a pawl 23, Fig. 3, maintained in engagement by a multiple spring comprising a coiled spring 24 and a flat spring 25. The actuating handle 29 is mounted rotatably on the end of the shaft and carries a pawl 31, Fig. 4, which engages ratchet teeth integral with the shaft. A pin 59 on the pawl serves as an actuating member and also as an anchorage for a spring 32. This spring is coiled about the pivot 30 of the pawl, and engages the adjacent wall portion 7 of the handle. An angular flat spring extension 34 of the pawl is apertured to receive the offset end 135 of a rod 35 which is reciprocated by moving the finger lever 37. When this lever is depressed towards the handle, the part 135 bends the spring 34 before the pawl 31 is moved radially outward from the teeth provided there is a load on the pawl, but if there is no load, then the pawl is released without the spring 34 bending since this spring is slightly stronger than the spring 32. Another slot in the spring is engaged by the bent end portion 91 of a U-shaped spring which is pivoted at 89 on a shaft 80 and has an offset part 90. The shaft 80 is slidably and rotatably mounted in the handle housing 7, and its end 87 at the end of arcuate movement upon either side of the housing normally engages abutments 88, Fig. 3, thereon, but the shaft can be moved longitudinally in order that the end may clear the adjacent abutment and the handle be moved beyond the centre and to the other side of the housing. A shaft 101, Fig. 3, extends into the housing and is turned by a finger piece 44. Within the housing the shaft carries an eccentric pin 42 which rotates a reversing ring comprising plates 48, 148 spaced apart by three pins 100 and mounted rotatably on the hub portion 15 of the housing. The plate 48 includes diametrically opposite segmental projections 46, 146 having an arcuate periphery 46a and a radial face 56, respectively, which co-operate with the pin 59 to keep the pawl out of engagement with the ratchet teeth and to rotate the ring structure in opposition to springs 45, respectively. A spring 47 is attached to the reversing ring and to an arm 26 of the shaft carrying the pawl 23. When the shaft 101 is turned to the upward position, Fig. 3, tension is put on the spring 47, and the pawl 23 is caused to engage in the sprocket teeth 17 thus holding the chain, while the handle is reversed for additional movement. Free chain movement is obtained when the reversing ring is rotated counterclockwise by the springs 45, 47 until the pin 41 engages the arm 26 of the shaft 22 and tilts it to move the pawl 23 out of locking position with respect to the sprocket teeth 17.