Abstract: On or about December 7, 2006, an Overhead Bridge Crane with a main hoist (150 Ton) and auxiliary hoist (70 Ton) was being used to lift and tip an approximately 226,000 pound slide weldment for a metal stamping press. During that process, a drive component (coupling) of the auxiliary hoist, which is used to perform the tipping while the main hoist supports the weight of the piece, failed under the tipping load. According to the drive component manufacturer, the coupling was installed with the incorrect distance between the inner splined hubs, allowing the outer flanged cover to shift position and become disengaged from the hub on the RX107 output shaft (i.e. the teeth-to-teeth contact was such that when they side shifted, they became disengaged). This disengagement allowed the piece to fall on the tipped side as the wire rope unwound from its drum without the support of this drive mechanism. While supported by the main hoist, the piece rocked until equilibrium was attained. There were no injuries.