Importance

Loading Importance Indicators...

Abstract

A rotary trench cutting or rock milling saw unit is supported on a head for movement about two mutually perpendicular axes. The head is adapted for pivotal mounting on a backhoe boom or similar positioning structure. Rotary rock cutting wheels are driven by a hydraulic motor and a support vehicle for the saw unit includes a hydrostatic drive system with a variable displacement hydraulic pump driving variable displacement track drive motors which may be set in a slow speed operating mode for trench cutting operations or a high speed mode for tramming between work sites. A constant rate of power input to the saw unit is maintained by sensing saw drive motor supply pressure and adjusting track drive motor supply pump displacement to maintain a constant feed or rock cutting rate. The apparatus includes hydraulically operated actuators for rotating the saw unit and its support boom about a vertical axis with respect to the apparatus undercarriage, elevating the boom with respect to the undercarriage, and moving the saw unit about three mutually perpendicular axes with respect to the support boom. Each of the actuators includes a control valve which may be selectively positioned to operate the actuators in reverse directions, lock the actuators in a predetermined position, or permit the actuators to oscillate or rotate the saw unit with respect to the various positioning axes of rotation when the saw unit is confined in a trench.

Loading the Abstract Image...

First Claim