Why the undercarriage determines the true price of a used drilling rig
When inspecting a used crawler drill, check the track chains, rollers, drive sprockets, idlers, travel reducers and telescopic beams supporting the mast for wear or structural damage. Estimate necessary repair costs before negotiating the price. This guide applies to crawler drills; wheeled or truck-mounted drills follow different inspection procedures.
Undercarriage components work together. A worn drive sprocket may affect a new chain, and a seized roller can develop flat spots and cause a bumpy ride. The undercarriage also carries the mast and drilling equipment; assess its condition in light of actual wear, ground conditions and use, then estimate parts and repair labor from the inspection findings.
What the listing shows, and what it hides
The GLOBMACH equipment page includes views of the tracks, but these photos were taken for marketing. They can show the overall stance and the clean side of the machine. A used drilling rig undercarriage inspection starts with these photos, but it does not end there. The seller's photos may not show the inner track, the lower rollers hidden behind the track frame, or cracks in welds on the telescopic arm. You must ask for close-up photos of the machine in a service position.
Source video, if available, can help you observe movement, but footage of a drill travelling on level ground may not show a slow final-drive leak or whether the rollers rotate properly. Use the listing to compare the stated track shoe width and track configuration with the manufacturer’s specifications. Then proceed to the inspection procedures below.
Compare the left and right tracks
Do not inspect only the cleaner track. Uneven wear between the two sides merits further inspection. The layout of the boom and rock drill may cause the left and right travel systems to carry different loads. Compare track shoe width, link condition, roller rotation and sprocket profiles on both sides. Ask the seller to reposition the drill so you can see the inner and outer sides of the tracks at several points.
Have qualified personnel inspect wear on links, bushings, drive sprockets and rollers using the measurement locations and methods specified by the equipment manufacturer. Compare the measurements with the service or replacement limits for the model and record the results. Do not rely on visual inspection alone to decide whether a component has reached its replacement limit.
Rollers, sprockets and idlers: small parts, big bills
A seized lower roller may look normal from the outside, but it can generate heat and cause abnormal chain wear. With the drilling rig secured and the inspection performed by qualified personnel, observe the roller rotation during controlled track movement, and check for seal leakage, flat spots or abnormal temperature distribution. Record each suspect roller as a component that requires confirmation by a specialist and a price inquiry, rather than predicting remaining life from appearance alone.
Inspect the drive sprocket teeth for hooked wear or pointed tips. Hooked wear may indicate wear; qualified personnel should determine whether replacement is needed against the service limits for the specific model. Check the idlers and recoil tensioning system for cracks, guide wear and correct tension. Qualified personnel should check track tension under safe conditions using the equipment manufacturer’s method. A loose track may derail, while an overly tight track may increase the load on the final drive. Record the findings and evaluate them against the requirements for the specific model.
Inspect the travel gearbox separately
The final drive transmits torque to the tracks. External leakage is visible evidence, but internal wear can be present without leaks. Have a qualified operator move the rig forward and backward and perform controlled steering in a suitable flat area while the inspector notes track travel, response and abnormal noise from the reducer. Any hold or brake test must follow the exact model's manual and the site safety plan.
Inspect accessible breathers, plugs and fluid condition only under the service procedure for the exact drive unit. Where the seller permits, a technician may take samples for testing; do not open pressurized or unsupported components for a sales inspection. If operating evidence and service access are refused, keep the uncertainty as a priced risk or an expert stop point.
Telescopic track beam: where structural repairs are hidden
Many modern drills have an extendable undercarriage that can be extended or retracted to adjust transport width or stability. This mechanism is a structural system containing sliding beams, wear pads, locking pins and hydraulic cylinders. Inspection of a used drill undercarriage must include a movement test. If conditions permit, qualified personnel should fully extend and retract the tracks under safe conditions, following the manufacturer’s procedure for the specific model. Watch for binding, uneven movement or hydraulic cylinder leaks.
Check around the track frame for disclosed weld repairs, deformation, paint discontinuities and cracking. Do not scrape or grind the seller's machine without written permission and a qualified inspection plan. If repairs are suspected, request their history and escalate to appropriate non-destructive or structural inspection before accepting the frame for transport or operation.
Estimate parts and repair labor based on measured wear
You have already gathered measurement data and observations. Now convert them into money. Contact local parts suppliers to get the costs for track chains, track pads, track rollers, idler wheels, drive sprockets, and final drive overhaul. Add the labor hours given by the repair manual or by a crane and heavy equipment repair shop. This total is your "undercarriage repair range." Subtract a reasonable portion of that range from the asking price.
Compare measured wear against the replacement limits and measurement methods published for the exact undercarriage; there is no universal percentage that applies to all brands and components. Turn items confirmed to be out of limit into parts and labor-hour ranges. If track structure, extension systems, or final drive performance cannot be safely verified, keep the issue as an inspection hold point rather than guessing at a discount.
Questions that move the seller from verbal claims to evidence
Do not accept a statement like “the undercarriage is in good condition.” Ask specific questions: What is the original track shoe width for this machine, and how does it compare with the factory specification? Have any chain links been replaced individually? When were the track rollers last greased? Is there a record of chain elongation measurements? The seller's answers often reveal how much documentation exists.
Cross-check the answers against what you see in the GLOBMACH listing. If the listing shows a narrow transport version while the seller claims it is a wide configuration, there is a conflict. Use the manufacturer's official documentation to verify the track dimensions for the exact model. Ask for the transport width data from the original brochure. This is key information for transporting the drilling rig.
Decision rules before you request a quote
If the used drilling rig undercarriage passes both the structural and final drive checks, but the track rollers and drive sprockets show moderate wear, include the replacement cost in your total cost of ownership. If uneven wear is measured and there are no maintenance records, ask for a lower price to cover this uncertainty. Never ignore final drive oil leaks or a bent track frame.
Finally, please provide the ground conditions, expected transport distance, transport width restrictions, local parts availability, and planned maintenance windows. This information helps technicians determine whether the observed configuration and wear are suitable for the working conditions. Please send the exact stock ID, measurement results, and any unresolved open questions to GLOBMACH so that the reply can include specific evidence for that stock item and a comparable parts scope.
