TL;DR

A rig that pulls to one side has a track tension or drive motor imbalance. Check and equalize track tension before looking at the hydraulic drive motors.

What you might see

rig pulling to one side during tramming
track chain link worn or elongated beyond gauge
track drive motor overheating
abnormal noise from the track roller

Likely causes

Tap to mark as ruled out

Track chain elongated beyond specification causing the chain to derail
Unequal track drive motor output from worn motor on one side
Track tension too loose from worn chain or incorrect tensioner adjustment
Roller or idler wheel bearing seized causing increased drive resistance on one side

Required tools

Tape measure or sag gauge
Track tensioner grease pump
Wrench set
LOTO kit

Safety first

Never adjust track tension with the rig engine running. The track can move suddenly.
Lockout the rig engine before working in the undercarriage area.

Procedure

6 steps · ~60 min

1
Park the rig on a flat, stable surface and lower the mast to travel position. Lock out the engine.
Warning: Never work under or in the undercarriage area with the engine running or without the rig fully grounded and stable.
2
Measure the track sag on each side by pressing down on the upper track run midway between the carrier rollers. Sag should be within the specified range.[1]
3
If sag is excessive, adjust the track tensioner grease fitting until the sag is within the specified range.[1]
4
Inspect each carrier roller, bottom roller, and front idler for seized bearings by checking free rotation by hand.
5
Inspect the track chain links for cracks, bent plates, or pins worn beyond the service limit.
6
Restart the rig and tram a short distance. Confirm the pull-to-one-side fault is resolved. If it persists, the track drive motors may have unequal flow. Check relief valve settings on each track drive circuit.

Sources

Sandvik Sandvik DR / DI / DT Drill Rig (Surface / Underground) general technical documentation, Sandvik
Sandvik drill rig undercarriage and track drive maintenance documentation (general)

More guides for Sandvik Sandvik DR / DI / DT

How to diagnose compressor air pressure loss on a Sandvik DR / DI / DT drill rig

Low drill air pressure is usually a dirty air filter, worn compressor valves, or a leaking rotary head seal. Check the filter first because it is the fastest and easiest fix.

~45 min7 steps

How to diagnose rotary head hydraulic faults on a Sandvik DR / DI / DT drill rig

Low rotary head speed means the rotation hydraulic motor or its control valve is restricting flow. Measure rotation circuit pressure and compare to the relief valve setting.