By adopting the technical scheme, the device has a simple structure, can keep the guide rails to be always unblocked, and further has no influence on movement of a front telescopic guide rail.

The utility model discloses a telescopic boom guide device and a telescopic boom of a crane, and relates to the field of the telescopic crane.

The utility model relates to a color TV projection amplifier which is composed of a machine frame, guide rails, lenses, apertures, a telescopic camera obscura, a camera obscura interface, etc.