| 摘要 |
1,188,445. Winches. W. L. BLACKBURN. 25 Oct., 1968 [19 April, 1968], No. 50665/68. Heading B8B. A ratchet winch for a cable 24 comprises a drum and ratchet wheel 18 secured to a shaft 16, the drum being driven by alternate engagement of dual pawls 40, 42 with the wheel 18 when a lever 30 is reciprocated, the pawls being urged by leaf springs 54, 56 into engagement with the ratchet wheel 18 when a control lever 28 is in a first position for hauling in cable and urged out of the engagement when lever 28 is rotated into a second position for paying-out cable. Rotation of the lever 28 rotates a cam 46 about point 44, the cam being linked to the pawls 40, 42 via a pivot 48 for a link 50, the remote end of which is pivoted to the spring 54 and to another link 52 coupled to the spring 56. When hauling in cable, the pawls are urged towards the ratchet wheel 18 and due to their eccentric pivoting 36, 38 on a rocker shaft 34 connected to the lever 30, alternately engage teeth 20 on the wheel 18 as the lever 30 is reciprocated, both pawls automatically engaging teeth on the wheel to lock it if the lever 30 is released with tension in the cable 24. During paying-out of the cable, the pawls still alternately engage the ratchet teeth as the lever 30 is reciprocated, but since the pawls are being urged out of teeth engagement, as one pawl takes over ratchet tooth engagement from the other at the end of a lever stroke, the other pawl drops out of tooth engagement and does not re-engage until the next lever stroke. The top pawl 40 is guided into re-engagement with the teeth 20 by using the bottom engaged pawl 42, whereas the latter uses a guide cam 66. In a modification of Figs. 10 to 15 (not shown), both pawls are guided by cams which are brought into their operative position only when the paying-out operation is to be performed. In the embodiment of Fig. 7 (not shown), a manually adjustable brake is actuable on the ratchet wheel to assist in paying-out cable. In the embodiment of Figs. 19, 20 (not shown), the pawl actuating lever is reciprocated by a crank arm eccentrically pivoted to a ratchet wheel driven manually by a hand wheel. The ratchet wheel has an associated pawl whereby the cable drum may be halted at much smaller increments of rotation than was possible with just the dual pawl ratchet wheel. The apparatus may take the form of a chaindriven hoist or the lever may be reciprocated by powered means. |
