Relational database management systems

The lower end of the dipper stick of a crane has spaced plates with L-shaped engaging edges forming a female pressure member which coacts with a male pressure plate in the upper end of an implement such as a clamshell bucket. A short flexible connector is connected at its lower end to the male pressure plate and has its upper end within the space between the two plates of the female pressure member, there being means within the cavity at the lower end of the dipper stick for releasably taking up slack in the flexible connector to provide a desired amount of snugness or looseness in the connection between the bucket and the dipper stick, with, however, the male and female pressure members always being engaged in a manner which will prevent rotating movement or undesired swinging of the implement relative to the dipper stick. A guide roller in the female pressure member coacts with one of the connector links to allow the bucket to be snugged up in most positions.