Patent ID: 7234400

Claim:
A crane trolley, comprising: a traveling mechanism frame having a hoisting mechanism, said traveling mechanism adapted to travel by running wheels on a rail, wherein at least one of said running wheels comprises a driven running wheel; at least one friction roller interacting with said driven running wheel, said at least one friction roller being arranged on the underside of said rail; and wherein said at least one friction roller comprises a pair of friction rollers, said pair of friction rollers adapted to be positioned against the underside of said rail by adjusting the spacing of the rollers relative to each other via a common adjusting mechanism acting on both said pair of friction rollers such that each said friction roller of said pair of friction rollers has substantially the same radial load; wherein said pair of friction rollers is arranged symmetrically with respect to an axis of rotation of one of said running wheels underneath that running wheel, wherein said pair of friction rollers is secured to said traveling mechanism frame by two double-arm levers that can swivel about a common axle, and one of said friction rollers is mounted to turn at one free end of each of said levers, wherein the other two free ends of said levers are joined together by a spring-loaded adjusting mechanism; wherein said adjusting mechanism comprises a screw joining together the two free ends of said levers and a compression spring which can be placed an the screw and tightened by a nut.