Methods and apparatus for cutting circular slots in pavement extending about manhole castings

摘要

A self-propelled core-cutting apparatus is used to cut circular slots in pavement extending about manhole castings and the like to permit castings and surrounding cores of pavement to be removed quickly and easily for such purposes as elevating the level of manhole castings to align with new pavement. The apparatus has a transport carriage to which are connected 1) a large diameter, generally cylindrical core-cutting bit, 2) power-operated support and drive systems mounting the bit for vertical and rotary movement relative to the carriage along and about a vertically extending center axis, and 3) a power-operated stabilization system that makes use of the weight of the apparatus in maintaining desired positioning of the apparatus during cutting operations. Support for the core cutting bit is provided by a telescopically extensible array of cage-like structures that extend substantially concentrically about the center axis, including an outer cage that is rigidly connected to the carriage, and an inner cage that is movable vertically relative to both the outer cage and the bit. Job site positioning of the apparatus is effected by using lever or joystick controls to operate a fluid-motor-driven power-steerable wheel that also serves as one of three vertically movable components of the power-operated stabilization system. Preferred practice of the invention also makes use of other disclosed features.