Abstract: A coupling device or "quick coupler" which permits the rapid connecting and disconnecting of implements to an earth-working device having a hoe boom comprising at least one primary lifting arm fitted for a hinge pin and a "curling linkage" mechanism having either two idler links and a power link, or a single part functioning as an idler link interacting with a power link, either alternative being powered by hydraulic cylinder(s) and fitted for a link pin. The quick coupler has a housing, which can be temporarily attached to the hoe boom using the hinge and link pins or can be built into the hoe boom itself, and which contains a connection for attaching the coupling device to a variety of implements. The effective operating distance or range of motion of the connector can be adjusted so that the coupler can be used with various implements having different center line distances between the hinge and link pins.