Articulated material handling machine

Abstract

A double articulated material handling machine that is particularly adapted for use with a rotatable working tool having a cantilevered boom arm. The machine includes a front module, a central module, and a rear module with the front and rear modules being connected to the central module for pivotal motion about vertical axes. Steering of the machine is effected by double acting hydraulic rams which are mounted in symmetrical relation to the longitudinal axis of the machine. A pair of retractable and extensible stabilizers extend laterally from the central module. If the fluid steering rams on one side of the machine are retracted and the rams on the other side of the machine are extended, the front and rear modules are caused to turn through an angle relative to each other for steering or for placing the machine in a working position. The rear module may also be offset relative to the front module so that the rear traction wheels do not track or follow the front wheels which is desirable to prevent the rear wheels from following in the grooves made by the front wheels where traction is a problem. The present construction provides for improved stability to the central module against tipping forces caused by cantilevered loads on the end of the boom as the boom swings through a work radius. In a working position, the machine is articulated such that its longitudinal axis is generally parallel to the work radius of the boom arm which causes the front and rear modules to be positioned as counterweights against the load on the boom arm. The stabilizers are also extended and locked in place on the ground to provide further machine stability.