Nowadays, few operators really dive deep into studying repair techniques. The few senior repair experts usually keep quiet — and I understand why. No one’s skills fall from the sky; they’re earned through years of effort and practice. It’s like this: you can copy others, but you don’t want others copying you. Free technical support? Unless you’re a friend or part of a knowledge exchange, it’s rare. There are no more “Lei Fengs” in this business — only hornets waiting to sting!

What I want to share here is about the relationship between repair and inspection/maintenance — advice for those who truly care for their machines, or for company maintenance teams. These are conclusions drawn from decades of experience.

For small enterprises or independent operators, the biggest fear is the machine suddenly breaking down — especially when it happens at the worst possible moment.

I’ll never forget one case: a Komatsu D85A-18 bulldozer, on a bitterly cold winter night (-42°C). At 10 p.m., the track link snapped just as explosives were already wired up for blasting, with only an hour to go before detonation. Urgent? That doesn’t even begin to describe it! The track chain was scheduled to be replaced that weekend — just three days away.

Attempts were made to bind the broken track with steel wire rope to move the dozer, but the rope snapped immediately. A thicker rope wasn’t feasible in that spot. Fetching a replacement track chain wasn’t possible within the timeframe. Everyone was panicking, because the blast time was fixed for the entire site, not just that area.

Finally, one old mechanic carefully assessed the situation and decisively told the welder to heat the damaged link with an oxy-acetylene torch, hammer it near the pin, and weld it together. That temporary fix was enough to drive the dozer out of the blast zone safely.

Examples like this are plenty: machines tend to break down at the most awkward locations. If it weren’t awkward, we wouldn’t even bother telling the story!

Lessons from Practice

In the state-owned enterprise days, periodic maintenance schedules were strictly enforced. Machines were serviced on schedule, reducing the chance of sudden failures. But after reforms, many skipped inspections and maintenance, leading to costly downtime and missed deadlines.

Later, when I had more say in decisions, I worked with a “three-in-one” team (leaders, engineers, and experienced workers — a classic SOE management model) to establish a framework of condition-based maintenance, regular inspections, and timely interventions. This reduced unexpected breakdowns, ensured continuous site operations, and avoided the chaos of last-minute “firefighting repairs.”

Here are some practical points that others can borrow:

1. Operator Shift Handovers

• Enforce a strict handover procedure.

• Operators inspect the machine’s exterior and visible parts together during shift change.

• Any non-critical faults are logged in a handover record and signed by both parties.

• Machines without proper handover cannot return to work.

• This reduces disputes and ensures accountability — a very effective SOE practice.

2. Dedicated Inspection Personnel

• During downtime (operator meals, breaks), assign inspectors to check for cracks, leaks, loose bolts, and abnormal noises.

• Immediate issues get first-time fixes; others are scheduled for later repair.

• This prevents random failures and allows planned interventions.

• Example: In my SOE days, four of us (including one female mechanic) maintained 12 Hongyan dump trucks, 2 CAT966D loaders, 1 water truck, 6 Tatra dump trucks, and 1 D85A-18 dozer.

• Our proactive checks caught: leaking cylinder liners, gearbox oil leaks, axle misalignments, broken springs, Tatra axle oil leaks, engine wear, water pump failures, loader hose leaks, cold-start failures, and hydraulic overheating.

• These checks not only improved reliability but also reduced “downtime on site”, a key SOE performance metric.

3. Timely Repairs Within Controlled Windows

• Schedule repairs when convenient, rather than waiting for sudden failures.

• Example: Loader support shaft cracking — detectable early with hammer sound testing or fluorescence methods. A small weld repair early prevents major breakdowns later.

• Loose bolts, minor leaks, or low oil/coolant should be addressed immediately.

• Small preventive fixes save huge repair effort later.

4. Improve Repair Quality to Avoid Rework

• Even under site conditions, strive for quality.

• Example: After welding an axle sleeve, factory procedure requires tempering or normalizing to prevent re-cracking. On-site, at least use slow cooling methods.

• Cases of mass cylinder liner failures (due to poor coolant and ignored filter replacement) or counterfeit weak half-shafts prove that poor quality parts and shortcuts multiply breakdowns.

Conclusion

The relationship between repair and inspection is simple: inspection prevents repair, and timely repair prevents accidents. A culture of proactive checks, disciplined handovers, and quality work is the key to keeping machines reliable, especially under continuous operation.