Tescar Drill Rig Repair - Low Power and Poor Tracking

Date Posted:5 April 2017 

This week we had a Tescar drill rig brought in to us by a customer as it had a lack of power drilling and wouldn’t track straight when in use. 

In most cases when a tracked machine isn’t tracking straight we would initially look at a worn pump or worn travel motor as the culprit.  This particular repair is one of the strangest we have seen in our experience, and was purely due to an incorrect repair by another workshop a few years ago. 

We tested both the pump and motor institute, and both performed satisfactorily.  During our diagnosis we found that the pump had been marked as repaired a month before our customer had purchased the machine second-hand, without our customer’s knowledge.  When the pump was refitted to the machine before sale, the pump lines had not been fitted in the correct sequence.

On any piece of construction machinery running a Double-axial piston pump with a track drive, pump 1 will be fitted to the left track, and pump 2 to the right (or vice versa). Pump 3 and 4 (if fitted) will control ancillary functions such as blades and slewing gear. 


In this case, pump 1 had been fitted to the left track motor, and pump 3 had been fitted to the right motor.  Pumps 1 and 3 are different displacements; therefore the machine would never track straight as the track motors would be spinning at different speeds.  Pump 3 also runs a lower pressure and is fixed displacement, so the drill would never drill to its full potential. 

This was a simple fix but shows that it always pays to have properly trained technicians working on your machinery.