An hydraulic control arrangement (66) in association with a pipe relining
machine Includes fluid pressure supply and return lines (32, 33), a motor
controller (80) to control a motor (67) and a radial position controller.
The radial position controller supplies fluid under pressure to a radial positioning
arrangement (46) to set diameter of a relined pipe. The radial position
controller has a first normally closed valve (83) supplying fluid under
pressure to the radial positioning arrangement (46) and a second normally
open valve (84) allowing fluid to be withdrawn from the radial positioning
arrangement (46). The arrangement (66) allows the pipe relining machine
to be withdrawn in the event of a failure.
