Filter Belt Tracking: Causes and Cloth-Side Fixes
Your filter cloth keeps drifting to one side, wrinkles along an edge, or needs constant re-centering. Before you order a new belt, find out which of three places the fault is coming from.
Belt tracking on a horizontal vacuum belt filter can start in the cloth, in the machine, or in the process: an out-of-square seam or uneven cloth tension is cloth-side; rollers out of parallel and a failed tracking device are machine-side; one-sided feed, uneven wash water and scale building up on a roll are process-side. The same symptom — a belt that will not stay centred — comes from all three, which is why replacing the cloth on its own so often buys only a few weeks.
Does this match what you are seeing?
- The cloth keeps drifting to the same side and comes back off-line soon after every correction.
- One edge wrinkles, folds or rides up over itself.
- An edge rubs the frame or a roll end and starts to fray.
- Cake thickness is visibly different on the two sides of the belt.
- Drift got suddenly worse, and the seam looks different than it used to.
If that is not quite it
Edges are wearing but the belt runs straight Edge Wear (page not published yet — tell us directly)
The drift starts at a skewed, split or pulled-out seam Joint / Seam Failure
Cloth, machine, process
Three columns, kept separate on purpose. Two of them are not ours to fix, and pretending otherwise would cost you a belt.
- The seam is not square to the direction of travel — a joint sewn or fitted a little out of line steers the cloth every revolution.
- Tension or elongation is uneven across the width, so one side runs longer than the other.
- An edge is damaged or the edge treatment has failed, and the cloth no longer holds its width.
- The cloth was made to dimensions that do not match the machine, and it is being forced to fit.
- Rollers, drive roll or idlers out of parallel, or out of level.
- The tracking or steering device is sticking, mis-set, or dead.
- Friction over the vacuum box is not even side to side.
- On a horizontal vacuum belt filter, the rubber carrier belt is itself tracking off and taking the cloth with it — establish which of the two is actually moving before you touch the cloth.
A new cloth will not fix these.
- Feed is loaded to one side, so cake is thicker on that side of the belt.
- Wash water is not distributed evenly across the width.
- Scale or sticky build-up on a roll changes its effective diameter along its length — common in gypsum-type duties.
Correct these first, or the new belt inherits the fault.
Tracking complaints reach us most often from gypsum-type duties, where roll build-up is part of daily life: phosphogypsum filtration and FGD gypsum dewatering.
Work through it in order
Every step says what to look at, what to measure and what to photograph. Do it in this order and you finish holding everything an engineering quote needs.
- 00
Stop and isolate first
- Look at
- Machine stopped, isolated and tagged out before anyone goes near a roll or an edge.
- 01
Decide what is actually moving
- Look at
- Is the rubber carrier belt tracking off, or is the cloth moving relative to the carrier belt? These are two different faults.
- Measure
- Offset of the cloth edge from a fixed reference on the frame, at the same point each revolution.
- Photograph
- A wide shot of the run showing cloth, carrier belt and frame together.
- 02
Check the seam
- Look at
- Whether the joint is square to the running direction; any opening, distortion or missing fasteners.
- Measure
- Offset between the two ends of the joint across the width.
- Photograph
- Close-up of the seam, both faces. This is the same photo the engineering RFQ asks for.
- 03
Check both edges
- Look at
- Fraying, folding, heat marks, contact wear against frame or roll ends.
- Measure
- Whether wear is clearly worse on one side than the other.
- Photograph
- Close-up of each edge, labelled left and right as you face the discharge end.
- 04
Check the rolls
- Look at
- Scale, packed solids, damaged lagging, anything that makes one end of a roll effectively bigger than the other.
- Measure
- Parallelism and level of drive roll and idlers, by whatever method your site normally uses.
- Photograph
- Any build-up you find, before you clean it off.
- 05
Check the tracking device
- Look at
- Whether it moves freely, responds, and returns to centre.
- Photograph
- The device and its sensor position.
- 06
Check the feed
- Look at
- Cake thickness across the width at the end of the drainage zone.
- Measure
- Thickness at left, centre and right.
- Photograph
- The cake surface across the full width.
- 07
Record the pattern
- Look at
- Always the same side, or wandering both ways? Different loaded and unloaded? Different after a wash?
- Photograph
- Nothing to photograph — write it down. It goes straight into the failure description on the RFQ.
- 08
Copy the nameplate
- Look at
- Machine brand, model and serial number.
- Photograph
- The nameplate, lit from an angle so the flash does not wash it out.
Not sure how to measure the belt itself? See the measuring guide.
What can be changed in the cloth
Seam made square and to the right construction
The joint is built to the machine and checked for squareness, because a joint that is out of line steers the cloth on every pass.
Heat setting for dimensional stability
Stabilises the fabric so width and length hold under running tension instead of creeping unevenly.
Edge treatment
Keeps the edge from frilling and losing width where it runs closest to the frame.
Built to your measured dimensions
Width and length taken from your old belt and your machine, not from a catalogue size that is nearly right.
These cases are not solved by new cloth
Rollers out of parallel, a failed tracking device, and feed loaded to one side are machine and process problems. A new belt will at most mask them for a while, and then the fault comes back with a belt you have already paid for. Fix the machine first, then change the cloth.
Tell us your machine and what you are seeing, and we will say honestly whether we can help.
Which of these we can actually supply
Our own confirmed manufacturing range is not published yet. Rather than print a number we cannot stand behind, the table below is a to-be-confirmed list. Send your case and we will come back with what the factory has confirmed in writing for your dimensions.
| Cloth-side option | What it addresses | Confirmed range |
|---|---|---|
| Seam constructions we can build | Squareness, joint strength, leakage path | UNKNOWN — pending factory confirmation |
| Weave types and polymers available | Stability, chemical duty, release behaviour | UNKNOWN — pending factory confirmation |
| Heat-set dimensional tolerance | Width and length holding under tension | UNKNOWN — pending factory confirmation |
| Edge treatment options | Edge integrity and width retention | UNKNOWN — pending factory confirmation |
| Maximum belt width and length | Whether your machine is inside our range at all | UNKNOWN — pending factory confirmation |
Process detail on how belts are built: factory and quality control.
Replace it, or fix the filter first?
- Edge tearing or frilling that cannot be recovered.
- A seam that has failed repeatedly on the same cloth.
- Permanent deformation or uneven elongation of the fabric — the cloth no longer runs true even on a machine that checks out.
- Drift together with slurry leaking past the edge.
- The cloth body is sound and the machine fault is identified — fix the machine.
- Drift stops after roll build-up is cleaned off.
- Drift stops after the tracking device is freed or re-set.
- Drift only appears under one-sided feed and clears when feed is corrected.
If the cloth body is sound and the machine cause is clear, do not change the belt. Send us the photos and we will help you decide. We do not publish expected service life in months, because it depends entirely on your duty and your machine.
Decided it needs replacing? Next step is measuring the old belt →
The same facts, whether you ask us to diagnose or to quote
Tick these off as you collect them. Nothing here is stored or sent from this page — it is a scratch list for your own use.
Where tracking problems tend to come from
Phosphogypsum Filtration
WPPA duty on horizontal vacuum belt filters, where roll scaling is a recurring tracking contributor.
FGD Gypsum Dewatering
Desulphurisation gypsum dewatering — a different duty from phosphogypsum, and not the same belt.
Horizontal Vacuum Belt Filter Cloth
Endless belts built to your machine dimensions, with the seam and edge options that bear on tracking.
Questions we get about tracking
Is belt tracking caused by the cloth or by the machine?
Both happen. A seam that is not square, or cloth tension that is uneven across the width, is cloth-side. Misaligned rollers or a faulty tracking device is machine-side. Send photos of the seam and of both edges, and we will help you tell them apart.
Will a new belt stop the drift?
Only if the drift starts in the cloth. If the rolls are out of parallel or the tracking device has failed, a new belt runs true for a while and then goes off-line the same way. Work through the checks above before you order.
How long should a belt run before tracking gets this bad?
That depends on the duty — slurry, chemistry, temperature, machine condition and how the belt is run. We do not publish a service-life figure. Send your operating conditions and the old belt details and we will discuss what is realistic for your case.
These answers are engineering judgement, not measured results, and no FAQ structured data is published from this page until they have been verified by our technical staff.
Measure your old belt and send it to us
Width, length, seam type, edge condition, nameplate, and the photos from the checks above. That is enough for an engineering answer instead of a guess. No account, no registration.
Replacement cloth fabricated to your machine dimensions. Not an OEM spare part.