Pipe conditioning tool

A pipe conditioning tool comprising a drive unit to move said tool along a pipe and a work head configured to rotate by said drive unit about an axis of said pipe to condition a surface of said pipe, said drive unit including a frame including a pair of yokes, each having a bight extending across said pipe and a pair of legs extending from said bight at a spacing to accommodate said pipe, said legs extending to opposite sides of said pipe, a pair of arms pivotally connected to said frame on opposite sides of said pipe and moveable about a longitudinal axis to said pipe to engage said pipe to secure said frame to said pipe, said arms each having wheels connected thereto to engage said pipe and to support said frame for movement along said pipe, said arms being configured to move from an open position aligned with said legs to permit said pipe to pass between said arms to a secure position in which said arms extend toward one another from said legs to encompass said pipe, said legs extending radially beyond said work head and said arms to provide support for said tool upon removal from said pipe, said drive unit further including a ring gear having radially inwardly directed gear teeth and a plurality of guide rollers spaced apart about said ring gear and engaging said gear teeth, a drive gear engaging said ring gear and rotatable by a drive motor to impart rotation to said ring gear, said work head being connected to said ring gear for movement therewith.