| 摘要 |
<p>741,463. Ratchet gearing. NAAMLOOZE VENNOOTSCHAP BETONFABRIEK DE METEOOR. Nov. 26, 1953 [Dec. 31, 1952], No. 32892/53. Class 80(3) An intermittent driving device for rotating a table or other member 1 in steps comprises a driving pawl 17 and a stop pawl 16 both mounted upon a pivoted arm 13 which is actuated by the piston of a compressed air cylinder 25 when a movement of the table 1 is required. The pawl 17 is pivoted on side plates of the arm 13 at 18 and is loaded by a spring 19 to grip, when the table is stationary, a stud 5 of the table between it and the stop pawl 16, as shown in the Figure. On admitting compressed air to the cylinder 25 through a suitable valve controlled by a pedal, for example, a downward movement of arm 13 with pawls 17 and 16 is effected. The pawl 16 moves away from stud 5 and the pawl 17 swings inwardly against the pressure of spring 19 until a shoulder 30 thereon contacts the stud 5. A rotary movement is then imparted to the table 1 through pawl 17 until the stroke of the operating piston is completed. The rotation of the table continues owing to its kinetic energy and the stud 5 moves clear of the pawl 17 which then returns to its initial position. The operating air pressure is then released, preferably automatically, and the arm 13 also returns to its initial position by air pressure to the opposite end of cylinder 25 or by spring pressure. Another stud 5 of the table 1 will then approach the pawl 17 and striking its surface 32 will move it inward and be stopped by the pawl 16. The arm 13 may swing a little from its initial position shown to cushion the impact of stud 5 but will be immediately returned by the air or spring pressure to locate positively the table. A further operation can then be initiated by the operator. The pawl device may operate by a linear movement instead of a swinging one or a plurality of pawl devices may be arranged on a rotary disc which is stepped around to bring such devices into successive operation.</p> |
