System for mounting a tractor unit on a guide track

A mounting mechanism for connecting a weld head tractor unit to a guide track, comprising:

• a fixed block having a first set of rolling devices;
• a movable plate having a second set of rolling devices, the movable plate movable to adjust the distance between said first and second rolling devices;
• a clamping assembly having:
• a shaft extending from said fixed block and through said movable plate;
• a cam spring between said fixed block and said movable plate;
• a cam handle connected to said shaft and movable between an open position for disengaging said tractor unit to said guide track and a closed position for engaging said tractor unit to said guide track, the guide track comprising a first rail and a second rail;
• and
• wherein, when the cam handle is in an open position, a first distance between the first and second rolling devices is greater than a width of the guide rail;
• wherein when the cam handle is in a closed position, a first distance between the first and second rolling devices is approximately equal to the width of the guide rail.