The conveyor that won't track, and where to look first

It's Tuesday afternoon. The outfeed belt on line 3 is chewing its edge on the side frame again. The operator says it's been doing it since the weekend. Someone on the last shift has already had a go. You can tell, because one tail take-up is wound right in and the other is nearly out.

So you give it a quarter turn. It comes back to the middle. An hour later it's off the other way.

Most tracking jobs go wrong like this. The take-up gets used to steer the belt while the real fault sits somewhere else. Tracking is the last step, once everything else is right.

Watch it before you touch it

Stand outside the guards and watch a few full laps of the belt. Where it runs off tells you most of what you need.

• If it runs off at the same spot every lap, the fault is fixed to the frame. Look at that spot and just before it. A roller out of square, a seized roller, build-up or a bent leg.
• If the run-off moves round with the belt, the fault is in the belt. Put a chalk or paint mark on the splice and watch. If the wander follows the mark, suspect the joint or the belt itself.
• If it runs true empty but wanders loaded, look at how the load goes on.
• Off at the tail? Look at the tail pulley, the take-ups and the return rollers leading in. Spillage that gets onto the return run usually ends up on the tail pulley.
• Off at the head? Check the head pulley, any snub roller and the last few carry rollers.
• On the return side, look hard at the return rollers. They run on the dirty side of the belt, so that's where build-up lives.

One rule does most of the work

A belt moves toward the end of the roller it touches first. Every adjustment follows from that. Skew a roller so one end meets the belt sooner, and the belt walks toward that end. A pulley with build-up on one side is fatter there, and it steers the belt the same way.

That's why squaring up one bad roller usually beats skewing a good one to fight it.

Square and level first

Isolate the conveyor and lock it off before you put a tape on it.

Check the frame. Measure the diagonals corner to corner on each section. They should match. Put a level across the width at the head, the tail and a few points between. Floors settle and legs get clipped by pallet trucks. A frame that's out of square will beat any amount of adjustment.

Then check the pulleys. Measure the diagonals between the head and tail pulley shafts. They should match too. Work along every carry and return roller you can reach. Most sit in slots, and some will have been knocked or refitted crooked.

Spin every roller

With the conveyor still isolated, spin each roller by hand. A seized roller drags the belt and wears a flat in itself. It's a fire risk as well. HSE's code of practice for PUWER gives a "conveyor belt on jammed roller" as an example of overheating from friction (L22, summary of regulation 12).

Then look at the surfaces. Product, glue, label backing or dust can build up on a pulley or roller, often more on one side. That turns it into a cone. A crowned pulley with its crown worn flat, or packed level with dirt, loses its steering too.

Clean it with the conveyor isolated. Never scrape a running roller. HSE's mining safety alert describes a worker killed after trying to clean compacted fines off a rotating deflection roller with a hand scraper (HSE safety alert).

Check the joint and the belt

If the wander followed your chalk mark, the splice is the first suspect. A joint that isn't square to the belt edge will push the belt over every time it passes a pulley. Check it with a square across the belt at the joint. A crooked splice needs remaking. No amount of tracking will cure it.

If the splice is square and the belt still wanders round its whole length, look for camber. That's a belt curved like a banana when laid flat. Slacken it off, or lay a length out flat, and sight along the edge. Bad camber means a new belt, or at least a new section.

Check the edges too. A belt that's been rubbing the frame gets a frayed or stretched edge, and it won't run like the other one.

Set the tension evenly

Before any tracking, set both take-ups to the same tension. Measure the travel on each side so you know they match. A slack belt slips and wanders, and a crowned pulley needs some tension to steer. Too tight loads the bearings and stretches the belt.

If the belt only tracks with one take-up wound far in, something else is wrong.

Then, and only then, track it

Now you can track it. Small moves, one change at a time. A quarter turn on a take-up is plenty. Then let the belt run several full laps before you judge it. Belts are slow to settle and quick to fool you.

Track at the tail or a snub roller where you can. Adjust the take-up on the side the belt is running toward. Tightening that side moves the belt away from it.

Self-aligning training idlers and guided belts have their place. But they only hold a belt on line. Whatever pushed it off is still there. A training idler with a seized pivot is just a skewed roller that's stuck. If a guide strip keeps jumping out of the pulley groove, the fault is getting worse.

Then there's the trap from the opening. Wind one take-up hard to drag the belt back, and the tail pulley ends up skewed. One edge runs tighter than the other and the bearings take uneven load. And the day someone fixes the real cause, the belt runs off the other way.

Keep your hands outside the guard

Tracking usually means watching the belt run. That's where people get hurt. HSE's code of practice for PUWER names the risk of being "trapped by the intake between drum and moving belt" on belt conveyors (L22, paragraph 148). HSE's food industry guide says conveyors are involved in 30%* of all machinery accidents in food and drink. Most of those injuries involve well-known hazards such as the in-running nip between belt and end roller (HSG252, page 18). Tail pulleys, snub rollers and take-up pulleys all have one.

Here's our position. You should be able to track a belt without opening a guard. PUWER requires guards built to allow maintenance work, "if possible, without having to dismantle the guard" (regulation 11(3)(h)). Regulation 22 asks for equipment built so risky maintenance can be done while it's shut down, so far as is reasonably practicable. The code of practice gives the example of "adjustment points positioned so they can be used without opening guards" (L22, paragraph 219). HSE's quarry guidance says that with good design, belts "can be tracked and lubricated without removing the guards" (HSE).

So if your take-up screws sit behind a fixed guard, that's a design fault. Fix it by bringing the adjusters out through the guard. Until then, make each adjustment with the conveyor isolated, refit the guard, then run it and watch.

If the belt really has to run during the work, the code of practice expects extra measures. Crawl speed on a hold-to-run control is one example (L22, paragraph 221). Adjustments done running also need more information, instruction, training and supervision (L22, paragraph 150).

What to do on Monday

1. Walk your conveyors and list every take-up and tracking adjuster you can't reach without opening a guard. That's your guard redesign list.
2. Check both take-ups on your worst belt. If one is wound much further than the other, find out why before anyone touches it again.
3. Add "spin every roller, check pulleys for build-up" to the PPM sheet for each belt.
4. Start a tracking log on each conveyor: date, what was adjusted, and how many turns.

* Conveyor accident figure from HSG252, second edition (2015), correct as of 26 September 2026. Paragraph numbers refer to L22, fourth edition (2014, amended 2018).