Abstract: A suspended cradle for use in the inspection and maintenance of difficulty accessible structures comprises a frame provided with a series of at least three roller assemblies each having rollers for running on an overhead track on the structure to be inspected or maintained and thereby suspending the frame for movement along the track. Each roller assembly has means for rendering the roller assembly inoperative by relieving the load on the rollers and withdrawing the rollers from the track so that the inoperative roller assembly can move past an obstruction on the track while the frame remains movably supported on the track by the remaining roller assemblies.