Two Caterpillar part numbers for one air cleaner element is not a data error. It is a real split in Cat's fitment tables, and it decides which number a parts book prints for a given machine. This page puts the two numbers side by side — the published figures, the machine lists, the aftermarket replacements that cover both — and then deals with the number most buyers forget, the secondary element 346-6694.
Two Numbers, One Specification Sheet
Open the Cat parts store page for 346-6693 and you get: Standard Efficiency Engine Air Filter, primary, non-round, overall width 8.016 in, overall depth 8.327 in, overall height 13.228 in, media type standard, material thermoplastic plastic. Open the page for 539-6920 and you get a different name — Primary Efficiency Air Filter, Cat primary air cleaner element — and the same figures, digit for digit, with the same non-round shape and the same material callout. There is no dimension anywhere in either specification table that separates them.
The element behind both is shared too: 346-6694, the secondary element for the same square housing, published at 6.594 in wide, 1.484 in deep and 11.634 in high. On this machine family the primary and the secondary are bought as a pair, whichever primary number your book prints.
| Element | Cat number | Type | Cat's published size | Shape |
|---|---|---|---|---|
| Primary (outer) | 346-6693 | Primary, standard efficiency | 8.016 in (203.6 mm) wide × 8.327 in (211.5 mm) deep × 13.228 in (336.0 mm) high | Non-round |
| Primary (outer) | 539-6920 | Primary, Cat primary air cleaner element | 8.016 in (203.6 mm) wide × 8.327 in (211.5 mm) deep × 13.228 in (336.0 mm) high | Non-round |
| Secondary (safety, inner) | 346-6694 | Secondary, standard efficiency | 6.594 in (167.5 mm) wide × 1.484 in (37.7 mm) deep × 11.634 in (295.5 mm) high | Non-round |
Where the Two Machine Lists Actually Differ
The interesting part is not the element, it is the fitment table. Cat's 346-6693 page lists the 966F and 966F II wheel loaders and the MH3037 material handler; the 539-6920 page lists none of those three. Run it the other way and the 963K track loader, the PL61 pipelayer, the 140 GC motor grader, the M314F through M323F wheeled excavators, the AP1000 and AP1055 / BG paver range and the TR16-C7.1 transmission appear under 539-6920 only.
| Machine | Listed under 346-6693 | Listed under 539-6920 | Secondary 346-6694 |
|---|---|---|---|
| Caterpillar 966F / 966F II wheel loader | Yes | No | Yes |
| Caterpillar MH3037 material handler | Yes | No | Yes |
| Caterpillar D6N / D6N LGP / D6N XL / D6N OEM | Yes | Yes | Yes |
| Caterpillar D6K2 / D6K2 LGP / D6K2 XL | Yes | Yes | Yes |
| Caterpillar D4 / D5R2 dozer | Yes | Yes | Yes |
| Caterpillar 953K track loader | Yes | Yes | Yes |
| Caterpillar 963K track loader | No | Yes | Yes |
| Caterpillar AP600F / AP655F paver | Yes | Yes | Yes |
| Caterpillar AP1000 / AP1055 / BG paver range | No | Yes | Yes |
| Caterpillar M314F – M323F wheeled excavators | No | Yes | Yes |
| Caterpillar PL61 pipelayer, 140 GC motor grader | No | Yes | Yes |
| Caterpillar TR16-C7.1 transmission | No | Yes | Yes |
| Caterpillar 2384C / 2384D / 2484C / 2484D / 559C / 559D / 579C / 579D knuckleboom loaders | Yes | Yes | Yes |
Two caveats on that table. First, it is our reading of what Cat's item pages show today, and those pages paginate their fitment lists behind a "View More" control — so a machine missing from the list is a machine Cat has not shown us, not a machine the element can never fit. Second, the 966F family is where the practical value sits: those loaders still work in bulk yards, quarries and ports across Africa, the Middle East and South America, and their parts books print 346-6693.
What the Aftermarket Calls Both of Them
If you source on a filter brand rather than a Cat number, this is the useful half of the page. Donaldson's published competitive-fit table groups the C34540/1, PA30275, P636408, AF4243 and WA10115 family against Cat tractors, loaders, excavators, pavers and forestry equipment plus CNH tractors — and Donaldson's own product page for P636408 lists Cat 346-6693 and Cat 539-6920 together as the numbers it replaces. That is a filter manufacturer stating on paper that one element covers both Cat numbers.
| Brand | Number | Notes |
|---|---|---|
| Donaldson | P636408 | Primary element, obround PowerCore media; Donaldson publishes 336.4 mm long × 202 mm wide × 215 mm high. Listed against both Cat numbers |
| Baldwin | PA30275 | Quoted against both Cat numbers |
| Fleetguard | AF4243 | Quoted against both Cat numbers |
| WIX | WA10115 | Quoted against both Cat numbers |
| MANN & Hummel | C34540 / C34540/1 | Also carries the AGCO / Fendt reference |
| HIFI Filter | SA17479 | Common in EMEA aftermarket stock |
| Others seen against this element | NAPA 500115 · SF Filters SL82512 · Wismet WAI104340 · Liebherr 12265207 · Wirtgen 2357645 · Knorr-Bremse 792498 | Equipment-brand references, mostly from road-building and earthmoving machines |
One difference worth knowing before you substitute: Cat's element is a non-round pleated panel, while Donaldson's P636408 is an obround PowerCore design. Donaldson publishes it as the competitive-fit replacement and the envelope dimensions agree to within a few millimetres, but the two are not the same construction. Check the seal face and the housing gasket on the machine, not just the length, width and height.
How to Settle It on Your Own Machine
Three checks, in this order. Measure the element you have taken out: width, depth and the height of the pleated pack, not a diameter — this element is non-round, and any supplier quoting you a diameter for it is quoting a different part. Compare against 8.016 in, 8.327 in and 13.228 in. Then read the number printed in the parts book or on the old element's end cap, and if it says 346-6693, order 346-6693: that is the number Cat lists for the 966F and 966F II, and there is no advantage in swapping numbers on a machine whose book is unambiguous.
Then order the second element. Every machine on both lists uses 346-6694 behind the primary, and it is the item that turns a filter change into a second filter change two weeks later if it is missed. Cat's filters guidance is blunt about it: the secondary element is never cleaned, and it is changed with every third primary change or as required. Blowing one out with compressed air drives the retained dust deeper into the media, which is worse than leaving it alone.
What This Page Deliberately Does Not Claim
It does not claim that Cat has superseded either number — Cat lists both, and we sell both. It does not publish a price, because the honest variables are quantity, shipping lane and whether you take the pair or the full service kit with the fuel and oil filters. It does not publish an operating-hour interval, because Cat sets that per machine, serial range and duty cycle, and a number on a web page does not override the manual. What it does instead is the cheap check: send the machine model and serial prefix, the number off the old element, or a photograph of it beside a tape measure, and we confirm 346-6693 or 539-6920 as the outer element and 346-6694 as the inner, quote both, and dispatch from Shanghai stock in 3–7 days, FOB Shanghai or CIF to your port.
FAQ
Q: Are Cat 346-6693 and 539-6920 the same filter?
A: They are the same element by every published figure. Cat's parts store lists 346-6693 as a Standard Efficiency Primary Engine Air Filter and 539-6920 as a Primary Efficiency Air Filter, and both carry 8.016 in overall width, 8.327 in overall depth, 13.228 in overall height, shape non-round, standard media and thermoplastic ends. Donaldson's competitive-fit table puts one number, P636408, against the Cat family that includes both, and Baldwin PA30275, Fleetguard AF4243, WIX WA10115, MANN C34540/1 and HIFI SA17479 are quoted against both. What differs is the machine list, not the filter.
Q: Which Cat machines use 346-6693 rather than 539-6920?
A: The 966F and 966F II wheel loaders and the MH3037 material handler appear on Cat's 346-6693 fitment list and not on the 539-6920 list. Going the other way, the 963K track loader, the PL61 pipelayer, the 140 GC motor grader, the M314F to M323F wheeled excavators, the AP1000 and AP1055 / BG paver range and the TR16-C7.1 transmission appear on the 539-6920 list and not on 346-6693. The D6N, D6K2, D4, D5R2, 953K, AP600F, AP655F and the 2384C to 579D knuckleboom loaders appear on both.
Q: Does a non-Caterpillar machine use the same element?
A: Yes, the same physical element is used on other brands. The Donaldson P636408 listing carries AGCO / Fendt H737200092100, Case / New Holland 73337834, Liebherr 12265207, Wirtgen 2357645 and Knorr-Bremse 792498 alongside the two Cat numbers, and Donaldson's competitive-fit table names CNH tractors as well as Cat tractors, loaders, excavators, pavers and forestry equipment. An agricultural dealer stocking this element is stocking a construction filter.
Q: Can I fit 539-6920 in a 966F II if 346-6693 is unavailable?
A: The two numbers measure the same and the aftermarket sells one replacement for both, but that is a judgement you should make with the old element in your hand, not from a web page. Measure width, depth and pleat height of the element you have removed and compare them with 8.016 in, 8.327 in and 13.228 in before substituting. We would rather quote the number your parts book prints and ship that.
Quote the Primary and the Secondary on One Order
Send the machine — 966F, 966F II, D6N, D6K2, D4, 953K, 963K or paver — with the serial prefix or a photo of the old element beside a tape measure. We confirm 346-6693 or 539-6920 as the outer element, 346-6694 as the inner, and can add the oil and fuel filters on the same service interval.
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