Description
Product Overview
The AF55020 is a heavy-duty cylindrical air filter element engineered for the Cummins QSF3.8 (3.8L), QSB4.5 (4.5L), and QSF2.8 (2.8L) industrial diesel engine platforms. These versatile engines power everything from skid-steer loaders and compact excavators to generators, compressors, and agricultural equipment. This filter delivers the precise balance of high airflow and superior dust-holding capacity required for continuous-duty operation in demanding environments.
Key Features
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Multi-Platform Compatibility: Direct fit for Cummins QSF2.8, QSF3.8, and QSB4.5 industrial engines across numerous OEM equipment brands
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Full Cross-Reference Coverage: Replaces AF55020, PA31004, 70024177, 46595499, and 5283826
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Compact Yet Powerful: Smaller cylindrical form factor compared to the AF55015, designed for the compact engine bays of skid-steers, mini-excavators, and generator enclosures
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Radial Seal Technology: Integrated radial lip seal ensures positive, vibration-resistant sealing — no gaskets needed
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Industrial Durability: Heavy-duty media withstands the vibration, temperature swings, and moisture exposure of off-highway equipment
Engine & Equipment Compatibility
| Engine Platform |
Displacement |
Common Applications |
| Cummins QSF2.8 |
2.8L I4 |
Compact equipment, small generators, light towers, pumps |
| Cummins QSF3.8 |
3.8L I4 |
Skid-steer loaders, telehandlers, compact tractors, compressors |
| Cummins QSB4.5 |
4.5L I4 |
Mid-size excavators, wheel loaders, forklifts, generator sets |
Specifications
| Specification |
Value |
| Part Number |
AF55020 |
| Cross References |
PA31004, 70024177, 46595499, 5283826 |
| Filter Type |
Cylindrical / Radial Seal Air Filter |
| Media Type |
High-Capacity Cellulose Blend |
| Seal Type |
Radial Lip Seal (integrated) |
| Service Interval |
500 hours (standard), 250 hours (severe duty) |
| Outer Diameter |
Approx. 7.5 inches |
| Length |
Approx. 12 inches |
AF55020 vs AF55015 — Choosing the Right Filter
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AF55020: Smaller form factor for QSF2.8, QSF3.8, and QSB4.5 (2.8L–4.5L engines). Used in compact to mid-size equipment.
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AF55015: Larger form factor for QSB6.7, QSC, and QSL9 (6.7L–8.9L engines). Used in full-size construction and marine equipment.
Always verify your engine model and existing filter part number — these filters are not interchangeable due to different housing sizes and airflow requirements.
Installation Instructions
- Locate the cylindrical air filter housing — usually mounted near the engine with a band clamp or latches securing the cover
- Release the cover fasteners and remove the cover
- Slide out the old filter element — note orientation if marked
- Inspect the housing interior — wipe clean with a dry cloth, check for any damage or corrosion
- Check the safety element (inner filter) if your housing is a two-stage design — replace if dirty (sold separately)
- Slide the new AF55020 filter into the housing — the radial seal should seat flush against the housing flange
- Replace the cover — ensure the filter is centered and the cover seats evenly
- Secure all fasteners — do not overtighten band clamps as this can distort the housing
- Reset the air filter restriction indicator if equipped
Frequently Asked Questions
Q: Will this fit my Bobcat T770 compact track loader?
A: The Bobcat T770 typically uses a Kubota engine, not a Cummins. However, many Bobcat E-series and newer compact equipment models use Cummins QSF3.8 engines. Always verify your specific machine's engine make and model before ordering.
Q: How often should I change the air filter on a skid-steer?
A: Skid-steers operating in demolition, grading, or agricultural applications should have air filters inspected every 250 hours and replaced at 500 hours or when the restriction indicator shows red — whichever comes first. Dusty conditions can cut service life in half.
Q: Does this include the safety/inner filter?
A: No. This listing is for the primary (outer) AF55020 filter only. The safety/inner filter is sold separately. The safety element should be replaced every third primary filter change or whenever it appears dirty — never clean and reuse a safety filter.
Q: Can a dirty air filter cause black smoke from the exhaust?
A: Yes. A restricted air filter creates a rich fuel condition (too much fuel, not enough air), which produces black smoke. On modern electronically-controlled Cummins engines, the ECM will typically derate the engine to prevent damage, but black smoke and power loss are classic signs of a clogged air filter.
Q: Is this filter suitable for marine use?
A: The AF55020 is designed primarily for land-based industrial applications. While the QSB4.5 is sometimes used in smaller marine vessels, confirm your specific marine engine's air filtration requirements. Marine applications often require additional moisture and salt-spray resistance.
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Blog Resources
Check out our Equipment Maintenance Blog for air filtration guides, filter cross-reference tools, and heavy equipment maintenance schedules.
