Indication means for indicating suitable conditions for the transfer of loads between two stations movable relative to each other in a vertical plane

摘要

For use with apparatus for transferring a load between two stations movable relative to each other in a vertical plane by means of a crane carried by one of the two stations having a hook assembly for attachment to the load on the other station for lifting the load, a lift-off indicator measures either the relative velocity or relative vertical accelerations of the two stations and from signals representing relative velocity of approach showing values between a maximum positive and a negative, and relative acceleration acting away from the direction of approach indicates conditions suitable for initiating lifting.