Abstract: Methods and apparatus are disclosed for releasably connecting a crane superstructure and a crane carrier. The apparatus includes a segmented clamp assembly which hydraulically engages mating flanges carried by the superstructure and the carrier respectively. The clamp assembly includes an arcuate segment to which two other arcuate segments are pivotally connected. The mating flanges may be tapered and one may comprise a lower appendage of the turntable. Centering devices are disclosed to assure proper positioning of the mating flanges during assembly. Suitable tensioning means are provided to create a tensile stress in the clamp and thereby wedge the mating flanges together. The methods disclosed concern disconnecting, attaching, and securing a crane superstructure to a carrier by circumferentially clamping mating flanges therebetween.