How to Judge Bucket Wear on a Used Wheel Loader
The bucket is a wheel loader's most expensive wear part; a new one costs twenty to thirty thousand yuan. Check four places: teeth, floor plate, welds, and pins. Mining machines grind teeth down to a third; municipal machines usually crack at the welds.
On September 7 a LiuGong 856 arrived at the warehouse, a 2017 machine. I circled the bucket for ten minutes and told the buyer: the bucket needs replacing; push the price down by 8,000 yuan. He disagreed, saying the teeth still had half left. I had him tip the bucket over and put calipers on the thinnest spot of the floor plate: four millimeters. He had nothing to say.
In wheel loader inspections, the bucket is what customers most often overlook and what costs the most money. A new bucket runs twenty to thirty thousand yuan, and in mining conditions one can be dead in half a year. This piece explains the inspection method thoroughly; follow it yourself and you can get a decent read.
One: Look at the Teeth
Teeth are consumables; replace them when they are worn, they are cheap. What matters is the tooth adapters. Teeth worn down to a third are normal. But if the adapters are worn through or weld-repaired, it means the previous owner would not even spend money on teeth; imagine what the rest of his maintenance looked like.
How to check: note the length of a new tooth, put calipers on the old ones. Two-thirds left is good, half is usable, below a third, make the seller fit new teeth before you talk price. Then look at the adapter roots: weld scars or cracks, and you directly ask the seller whether the bucket has been replaced.
Last month I inspected a machine with two of five teeth broken off; the breaks were old and rusted. The owner still claimed the machine was well maintained. A man who will not replace broken teeth, do you believe he changes his oil?
Mining machines go through teeth fast. A bucket has five or six teeth, a good set costs two to three thousand yuan, and mining conditions eat a set in two or three months. During inspection, ask the owner when the teeth were last changed. If he cannot answer, his maintenance log is probably blank too.
Two: Look at the Floor Plate
The floor plate is the bucket's life. Mining machines shovel rock, grinding the floor from sixteen millimeters down to eight, then six. Below four millimeters, one heavy scoop punches straight through.
How to check: have the operator roll the bucket up, get underneath, and put calipers on the middle-rear of the floor plate; that is where it wears hardest. Above twelve millimeters, relax. Eight to twelve, judge by price. Below eight, the bucket will not survive one rainy season; cut the replacement cost out of the machine price.
Watch for patched floors. Some buckets have an extra wear plate welded on; done well, it is a plus; done badly, it is a hazard, because material gets trapped between the layers and corrodes faster. Check the welds for porosity and undercut; tap and listen: a dull thud means solid, a crisp ring means hollow. Lao Li taught me this: take a small hammer and tap from left to right; where the sound changes, that is the void.
Do not measure the floor at just one point. Measure the four corners, the center, and near the lip, and take the thinnest reading. Some owners are clever: they weld a thick patch in the middle, so the center measures fine while the edges are long worn through.
Three: Look at the Welds
The welds connecting the bucket to the ears and side plates take the most stress. A loader lifts thousands of times a day, and fatigue cracking in welds is a common disease.
How to check: hold a flashlight flat against the weld and look across it; cracks show best in raking light. Focus on the ear roots and the two ends of the lip. Hairline cracks: the machine is still buyable, just haggle; a few hundred yuan of rewelding back home. Cracks that have opened into visible gaps: the bucket is damaged to the bone. Replace the bucket, or walk away from the machine.
The year before last I inspected a machine with a crack at the ear root. The owner had filled it with putty and painted over it; it looked smooth as glass. Under raking light, the little forks at both ends of the crack stood out plain as day. I passed on that unit, and the owner cursed me for meddling. Three months later that machine was sold to someone else. The bucket fell off.
Four: Look at the Pins
Too much pin clearance and the bucket wobbles, weak in work, and it grinds the bores oval. Once the bores are oval, it is no longer a matter of changing pins; the bores have to be re-machined, and that is real trouble.
How to check: start the machine, lay the bucket flat, have the operator feather the bucket tilt while you crouch and watch the pin joints for play. Then grab the bucket edge with your hands and shake hard. Clearance over three millimeters means pins and bushings need replacing, a few thousand yuan a set. If the clearance is big enough that the bucket rattles audibly, the bores are probably already oval.
Pins also tell you whether anyone greased the machine. Look at the grease nipples: if they are clogged and the area around them is dry and crusted, the bushings inside are eighty percent dry too. A dry-run pin looks fine on the surface but is scored inside.
Mining Machines and Municipal Machines Are Different
At the same hours, a mining machine's bucket and a municipal machine's bucket live in two different worlds. Mining wear is in the floor and teeth; it is ground away. Municipal machines shovel muck and clear garbage, so wear is light, but weld cracks are common; municipal work is mixed, operator skill varies, and rough handling is common.
Municipal machines have one more trap: swapped buckets. Some owners fit an oversized bucket for light material. It looks capacious, but the boom and pins are overloaded the whole time. During inspection, measure the bucket capacity against the factory spec. If it does not match, ask why.
So ask about the previous duty. For a machine off a mine, measure the floor mercilessly. For one retired from municipal work, shine the light on every weld mercilessly. In one sentence: a bucket fears cracks, not wear; it fears ugly repairs, not age.
Every loader we ship has a dedicated bucket page in the inspection report: caliper readings at the four areas, photos, any weld repairs, all in writing. The report travels with the machine. When it arrives at your port, check it against the report. If any number does not match, I will refund the difference.