| 摘要 |
A telescopic, length extensible device, having a plurality of telescoping hollow elements, including an innermost one, at least one further, and an outermost one, further indluded a drive connected for obtaining telescopic extension and retaction is improved by a device for ensuring a predetermined sequence in the extension and retraction of the element comprising a first pin mounted for radial displacement, on one of any two mutually adjacent ones of the elements, the first pin having slot means, and being provided for selective insertion into and retraction from a third one of the elements; a couter latch element for latching insertion under spring bias and connected to another one of the two elements, such that when latching obtains, the first pin is retracted from the third element; a second spring-biased pin has a nose for lateral engagement with notches in the first pin and a control lever, operates in response to positions of the third element for locking and unlocking the second pin so that the second pin releases or locks the first pin in a protracted position of insertion in the third element or for maintaining retraction therefrom. |
