Copying welding equipment

A tracking welder for automatically welding works along a predetermined welding line, comprising:

• a carriage provided with left and right side wheels rotatably supported respectively through a pair of bearing units pivotally mounted thereon;
• a driving source mounted on the carriage for driving said carriage;
• a transmission system mounted on the carriage for transmitting a rotational motion of said driving source to said left and right side wheels;
• a welding torch mounted on the carriage;
• a sensor mounted on the carriage for detecting the welding line;
• a track-controlling motor mounted on the carriage and rotating in forward and backward directions in response to a detection signal from said sensor;
• and
• a steering system mounted on the carriage for turning said bearing units as much as an amount corresponding to a rotational amount of said track-controlling motor;
• wherein said transmission system is provided with:
• a hollow outer cylinder rotatably supported on said carriage to be transmitted with the rotational motion of the driving source;
• an intermediate shaft disposed in the hollow of said outer cylinder and connected with axles of said wheels through universal joints at both ends of the outer cylinder;
• and
• a transmission pin passing through an oval hole formed in said intermediate shaft and engaged to said outer cylinder.