| 摘要 |
392,689. Locking switches. SIEMENS & HALSKE AKT. - GES., Siemensstadt, Berlin. Feb. 23, 1932, No. 5399. Convention date, Feb. 23, 1931. [Class 38 (v).] A switch 12 in series with a resistance regulator 1 for a cinematograph projector can only be closed when a certain minimum resistance is in circuit. When the switch is closed, the resistance can then be reduced to any desired amount. In the form shown, the shaft 2 of the resistance regulator carries a cam 3 which bears against a bar 4 sliding in bearings 6, 7 against the action of a spring 8. The end 4<1> of the bar 4 has flexibly mounted on it an extension 9 which comes in the path of the downwardly moving contact block 11 of the switch 12 when the resistance is below a certain amount, but if the switch 12 is already closed, the bar 4 can be moved from the dotted to full-line position to reduce resistance as desired, the extension 9 bending back in the process. An adjustable stop 14, 15 may also limit the movement of the cam 3, and a button 13 on the extension 9 allows the extension to be moved out of locking position by hand if desired. In a modification, an electromagnetic or mechanical arrangement is also operated by the rapid return of the extension 9 when the switch is opened to cause the regulator to move to a safe resistance. |
