| 摘要 |
885,148. Variable-speed gearing. BROWN INDUSTRIES Ltd., DAVID. April 29, 1960 [Feb. 16, 1959], No. 5241/59. Class 80 (2). [Also in Group XXII] A hob shift mechanism comprises hydraulic means 11 adapted periodically to rotate a pawl carrier 13 through 180 degrees and return it to its original position, a pawl 14 on the carrier 13 and engageable with a ratchet wheel 22 connected to a screw mechanism 23, 25 adapted to move the hob in the direction of its axis, and an adjustable masking plate 26 adapted to hold the pawl in an inoperative position for any desired part of the motion of the pawl carrier 13. The pawl 14 is fixed to one end of a pin 15 which is pivotally mounted in the pawl carrier 13 and has integral therewith at its top end a plate 33. The pawl 14 has alternatively operable tooth portions which may selectively be brought into engagement with the ratchet wheel 22 by operation of a lever 17 on a plunger 18 which may be moved into engagement with a slot 16 in the plate 33. Two pegs 25a are fixed to the plate 33 and may coact with the masking plate to prevent engagement of the pawls with the ratchet wheel 22. A spring-pressed shoe 21 holds the appropriate pawl in operative engagement. Adjustment of the position of the mask 26 is effected by operation of a lever 31 and gearing 27, 28. The screw member 25 is attached to a hob support bracket 43 and accordingly controls the location thereof on guides 44. A graduated position scale and limit switch are provided.
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