| 摘要 |
A load supporting platform, such as a workman's basket mounted on the outer end of a boom structure which is adjustable vertically and horizontally, wherein a pair of inflated resilient pneumatic tubes inflated to selected pressure are disposed in outwardly surrounding relation to the lower corner portions of the platform to contact and be deformed by objects or surfaces which are being approached by the platform, together with air pressure activated switch exposed to the pressure conditions in the pneumatic tubing and circuitry activated by the air switch to break the power circuit for the boom structure, collectively serving as a proximity sensing and protective system.
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