Abstract: An automated order fulfillment system and mobile robot are disclosed, where the mobile robot includes a compliant drive for moving between levels of a multilevel storage structure. In one example, the compliant drive comprises a drive shaft having splines configured to provide rotational play that prevents jamming of a vertical drive gear on the end of the shaft with a rack in a vertical track.

Abstract: Tamping tools for mounting in a ballast tamping apparatus such as the rail-mounted Canron, Plasser and Jackson ballast tamping machines designed for tamping ballast around railroad cross ties, which tamping tools each include a shaft adapted for mounting on a reciprocating mechanism in a respective ballast tamping machine, a shaped shank extending from the shaft, a weld ring or nut seated on the shank and welded to the shaft and a tool foot having a receptacle internally configured to receive the shaped shank, with the tool foot welded to the weld ring or nut for easy replacement. A blade is provided at the extending end of the tool foot in offset relationship for contacting and tamping the ballast and in a first embodiment the blade is formed integrally with the foot, while in a second embodiment the blade is bolted to the tool foot.