| 摘要 |
826,303. Ratchet gearing. COLUMBIA MALTING CO. Oct. 7, 1957 [March 15, 1957], No. 31295/57. Class 80 (3). In ratchet mechanism for rotating a drum such as a kiln for malting grain, the ratchet teeth of curved rack sections 13 secured around the drum 11 are engaged by a driving pawl in the form of a bar 39 carried between a pair of spring-loaded levers 37 pivoted on coaxial pins 35 held in a yoke 33 which is reciprocated by an hydraulic cylinder 21, the yoke 33 being located in relation to the rack 13 by means of the two pivot pins 35 which project into circumferential grooves 47 on opposite sides of the rack. Backrunning is prevented by three pawl bars 85, 86, 87 carried by links 82 pivoted to a pair of arcuate bars 73 in turn pivoted at 71 to a spring-loaded pull bar 51. The pivot pins 71, and the pivot pins of the links 82 all extend into the grooves 47. The bars 85, 86, 87 are so spaced that the drum cannot run back more than one third of a tooth space. Each bar is held against the ratchet teeth by a flat spring, Fig. 4 (not shown), secured to a respective yoke 76, Fig. 2 (not shown), interconnecting the two arcuate bars 73. The cylinder 21 may be single or double acting and is pivotally mounted at 27. After each operative stroke there is a slight backward movement of the drum which is cushioned by the spring 65 loading the bar 51, and which may also be cushioned by temporarily restricting the fluid flow to the cylinder 21. In a modification a second hydraulic cylinder and pawl mechanism is provided in place of, or in addition to, the backrunning-preventing mechanism, the two hydraulic cylinders being actuated alternately so that the drum 11 is continuously rotated. |
