How to Inspect a Used Mining Truck: Tires and Frame Come First

In July 2019, a customer in Inner Mongolia wanted used wide-body dump trucks for earthmoving at a mine — six at once. In early August I went to a mine outside Baotou to look at trucks: twelve inspected, six selected.

The twelve trucks came from three sellers, condition all over the place, quotes from 210,000 to 280,000. The August sun on the mine was vicious; the trucks sat on a hillside, and by the time I'd gone through them one by one, my shirt had soaked and dried over and over. The mine manager sent a veteran driver along with me — a man named Zhang, fourteen years on mine trucks.

I set the inspection order myself: tires first, then frame, then hydraulics and brakes, floor plates last. The order follows the money — tire and frame problems cost the most, so the most expensive pits get ruled out first.

A mine truck is not the same species as a road tipper. Mine roads are gravel ramps; loads start at seventy tons; trucks run twenty hours a day. Three years of that duty equals ten years of road wear. The inspection method is entirely different.

Tires first — 8,000 each

Tires are the mine's biggest consumable: one new off-road tire runs over eight thousand, and a truck wears six.

Three things to check. Tread depth — use a depth gauge; under fifteen millimeters, the tire is at the end of its life. Sidewalls — bulges and cuts; gravel-sliced gashes, even patched, blow out easily. And whether the six tires on one truck wore evenly — heavy wear on one side means axle alignment or frame trouble.

Of the twelve trucks, I walked away from two on tires alone. All six tires needing replacement — fifty thousand gone — and the price still wouldn't budge.

Driver Zhang taught me one trick: don't just look at tread depth, look at the direction of the wear pattern. Drivers who brake hard on slopes year-round grind diagonal stripes into the tread — tires like that slide easily in the rainy season.

Frame cracks: get underneath

The frame is a mine truck's lifeline. Fully loaded at seventy tons down a long grade, braking nose-dives the whole load onto the frame. A frame that's cracked is a time bomb, welded or not.

Checking cracks means crawling under the truck. Three key spots: the welds joining main frame and subframe, the area around the body hoist mounts, and the rear-axle suspension brackets. That's where stress concentrates.

My method is crude but it works: wire-brush the grease and mud off, spray cleaner, wipe dry, and look hard for fine lines. Where I'm not sure, I run magnetic particle testing — I carry the kit myself; a set costs 2,800.

That day I found a four-centimeter crack in a frame weld on the third truck. The seller said it had been welded, no problem. I said: welded means it cracked — this one's out. The seller's face went dark for a while.

Before crawling under, make sure the truck is properly propped — the bucket on timber blocks. Mines have had fatalities where the body hydraulics failed while someone was looking at a truck. I check the supports before every crawl-under. That order never reverses.

Hoist hydraulics and brakes

Two things on the hoist system. Hoist time: an empty body to full raise takes about twenty seconds new; past thirty-five seconds means internal leakage in pump or cylinders. And drift: raise halfway, kill the engine for ten minutes; if the body sags fast, the cylinder seals are done.

Brakes are a mine truck's life — long descents ride entirely on them. Check brake drum wear, whether brake chambers leak air, how fast the tank pressure drops. If you can, always do one loaded downhill run: after twenty consecutive brake applications, the pedal must not go soft.

One of the twelve passed every static check, but on the test slope the brakes went soft at the tenth application. The seller said there was water in the air lines. I didn't gamble. Out.

Mine trucks use air brakes plus exhaust braking; long descents can't ride the service brakes alone — the exhaust brake has to carry part. On test drives I let the seller drive and I ride shotgun, listening. A muffled exhaust-brake note means the butterfly valve is worn.

Floor plates: thickness decides

Mine truck floor plates are ten millimeters from the factory; three years of rock impacts wears them to five or six — normal. Measure with a thickness gauge: floor under five millimeters, side plates under four, and hauling hard rock means re-plating — one floor plate, labor plus material, is 15,000.

Also check the floor for bulging and deformation. Deformation means the driver overloaded for years, or dumped big rock without a dirt cushion.

For thickness I picked five points: four corners plus the center. The center is thinnest — rocks hit the middle. One truck still had eight millimeters at the corners but only 4.2 in the middle. You judge by the thinnest point, and that truck was out.

The six that made it

Of the twelve, I rejected six: two needing full tire replacement, one with a cracked frame, one with soft brakes, and two with too-thin floor plates and unmoving prices.

For the six survivors I wrote an inspection report each: tread depths, plate thicknesses, hoist times — every item listed as a number. The customer took the reports and bargained the six trucks down by 72,000 in total.

The report format is fixed: twelve exterior photos, eight undercarriage photos, tire data listed line by line, plate thickness taken as the minimum of five points. The customer can read it; the seller can't pick holes in it.

If you're buying mine trucks and don't dare crawl underneath, don't buy used. Or let us crawl for you. Every number in the report has a photo behind it — take the photos and verify with any third party you like.