Rotary dipper stick

Abstract

A vehicle having a fluid-powered rotary dipper stick assembly including a boom attachment head and a bucket attachment head with a body extending therebetween. An axle extends from the boom attachment head into the body and is in sliding engagement with an inward wall of the body to provide lateral support thereto. The axle extends to a midportion of the body. The body is rotatable relative to the axle, and is rigidly connected to the bucket attachment head for rotation together as a unit. A linear-to-rotary transmission mechanism including a piston is disposed within the body and is operable to produce rotational movement of the body relative to the non-rotating axle. The piston is operated by the application of pressurized fluid to produce linear movement of the piston which is translated into rotational movement of the body, and provides rotation of a bucket or other work implement attached thereto about the body longitudinal axis independent of the boom attachment head. The assembly uses a single thrust bearing positioned between the body and the boom attachment head to carry thrust loads in both directions. In one embodiment fluid passageways in the non-rotating axle and a rotary fluid joint conduct hydraulic fluid between the non-rotating and rotating components. In another embodiment the passageways are formed in a non-rotating bearing block of the thrust bearing.