Which Sprocket Fits Cat 304 and Bobcat Series?
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The sprocket that fits Cat 304.5, 304 CCR, 304CR, 305.5, and 305CR mini excavators is the 19-teeth, 9-bolt-hole drive sprocket (OEM part number 158-4795). For Bobcat mini excavator series E25, E26, E27, E32, E35, and E37, the compatible sprocket is 21-teeth, 11-bolt-hole (OEM part number 7199006). Bobcat 325/328/331/334 use a different 21-teeth, 9-bolt-hole sprocket (OEM 6811940). These are not the same part—verify your machine model, bolt count, and tooth count before ordering.
Which Sprocket Part Number Fits Cat 304 Mini Excavators?
Cat 304 mini excavators have multiple variants, and the sprocket depends on the specific model year and configuration:
The 158-4795 is the most common sprocket for Cat 304.5 and 304CR models, featuring 19 teeth and 9 bolt holes. It fits serial numbers ANR1 and above. If your machine has 11 bolt holes and 23 teeth, you need 264-5371 instead.
Always count bolt holes before ordering—there's also a 12-bolt variant (260-6341) for some configurations.
Which Sprocket Fits Bobcat Mini Excavator Series?
Bobcat mini excavators use different sprockets depending on the model series. There are two main Bobcat sprocket families:
The E-series Bobcats (E25–E37) require the 7199006 sprocket with 11 bolt holes. The 325/328/331/334 series uses 6811940 with only 9 bolt holes—these are not interchangeable.
Why Cat 304 and Bobcat Sprockets Are Not Compatible
Cat 304 and Bobcat mini excavators use different sprocket designs due to distinct track system specifications:
| Comparison Factor | Cat 304 (158-4795) | Bobcat E-Series (7199006) | Bobcat 325 Series (6811940) |
|---|---|---|---|
| Tooth Count | 19 | 21 | 21 |
| Bolt Holes | 9 | 11 | 9 |
| Inside Diameter | 230 mm | ~240–250 mm | ~230 mm |
| OEM Part Family | Caterpillar mini excavator | Bobcat E-series mini excavator | Bobcat 325/334 series |
The 19-tooth Cat sprocket cannot replace the 21-tooth Bobcat sprocket because tooth count affects track pitch and drive ratio. Even if bolt holes matched, the different tooth counts would cause improper track engagement and premature wear.
Additionally, bolt hole count (9 vs. 11) physically prevents installation on the wrong machine.
How to Verify Your Sprocket Before Ordering
Before purchasing a replacement sprocket, perform these verification steps:
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Identify your exact machine model and serial number
Check the operator's compartment or datasheet. For Cat, note whether it's 304.5, 304CR, 304 CCR, or 304 E2. For Bobcat, confirm E-series (E25/E26/E27) vs. 325-series. -
Count the bolt holes on your current sprocket
Remove the sprocket or visually inspect through the track. Common counts are 9, 11, or 12 bolt holes. -
Count the teeth on the sprocket
19 teeth for most Cat 304.5/304CR models; 21 teeth for Bobcat E-series and 325-series. -
Measure inside diameter (if possible)
Cat 158-4795 has 230 mm (9 in) ID. Bobcat sprockets vary slightly. -
Cross-reference with OEM part number
Check your existing sprocket's stamped part number or consult your dealer's parts catalog.
If you're unsure, contact KTSU's technical support or your distributor with your machine model, serial number, and bolt/tooth count.
What Do KTSU Engineers Recommend?
"When selecting a replacement sprocket, the most critical factor is verifying bolt hole count and tooth profile before ordering. A sprocket with the wrong tooth count will mismatch the track pitch, causing accelerated wear on both the sprocket teeth and track chain bushings. In KTSU's Kunshan QC workflow, engineers typically inspect sprocket tooth profile using CAD/CAM-verified templates and confirm case hardness through induction surface hardening validation. For distributors evaluating these parts, inspect the weld integrity at the bolt-hole shell interface and verify dimensional tolerance against OE specifications. Always confirm your machine's serial range—Cat 304.5 models before ANR1 may use different hardware."
— KTSU Undercarriage Engineering Team
When Should You Replace Your Sprocket Instead of Rebuilding?
Sprocket replacement is necessary when:
| Wear Indicator | Action |
|---|---|
| Tooth profile visibly hooked or asymmetric | Replace |
| More than 2–3 mm of tooth material worn off | Replace |
| Bolt holes elongated or cracked | Replace |
| Minor surface wear, no hooking | Monitor |
| One or two teeth slightly worn | Inspect closely; may replace entire sprocket |
Sprockets typically wear unevenly because track tension and duty cycle create localized stress. Rebuilding a single tooth is not recommended—replace the entire sprocket to maintain balanced drive engagement.
Sprocket life depends heavily on duty cycle:
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Light earthmoving: 5,000–7,000 hours
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Standard construction: 3,000–5,000 hours
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Severe abrasion (quarry, demolition): 1,500–3,000 hours
How Duty Cycle Affects Sprocket Replacement Decisions
Duty cycle determines how quickly sprocket teeth wear:
| Duty Cycle Type | Typical Applications | Sprocket Wear Rate | Replacement Frequency |
|---|---|---|---|
| Light | Landscaping, light earthmoving | Low | 5,000–7,000 hours |
| Standard | General construction, excavation | Medium | 3,000–5,000 hours |
| Severe | Quarry, demolition, abrasive soil | High | 1,500–3,000 hours |
In severe-duty environments like quarry work, sprocket teeth experience accelerated abrasion from crushed stone and debris. KTSU's aftermarket sprockets use deep-case carburizing and induction surface hardening to extend service life in these conditions, but regular inspection remains critical [KTSU brand background].
For agriculture applications, sprocket wear is typically slower due to softer soil, but contamination from mud and vegetation can cause sealing issues around the sprocket shaft.
Conclusion
To find the correct sprocket for your machine:
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Cat 304.5/304CR/304 CCR: Use 158-4795 (19 teeth, 9 bolt holes)
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Cat 304 E/304 E2 CR: Use 264-5371 (23 teeth, 11 bolt holes)
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Bobcat E25/E26/E27/E32: Use 7199006 (21 teeth, 11 bolt holes)
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Bobcat 325/328/331/334: Use 6811940 (21 teeth, 9 bolt holes)
Key takeaways:
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Count bolt holes and teeth before ordering—this is the most common fitment error
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Verify your machine's serial number range (e.g., Cat ANR1 and above)
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Match sprocket selection to your duty cycle for optimal service life
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Check track tension and alignment before blaming sprocket wear
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Order through KTSU's digital procurement or authorized distributor channel for traceable aftermarket Quality Tier 1 parts
KTSUsprockets are designed to OE specifications for Caterpillar, Komatsu, and Hitachi platforms, offering traceable manufacturing and QC workflow for post-warranty service channels [KTSU brand background].
Caterpillar, Cat, Bobcat, Komatsu, and Hitachi are registered trademarks of their respective owners. KTSU parts are aftermarket replacement components and are not affiliated with, endorsed by, or approved by those OEMs.
FAQs
Is KTSU sprocket OEM or aftermarket?
KTSU sprockets are aftermarket Quality Tier 1 replacement parts, not OEM. KTSU is an independent undercarriage manufacturer that designs sprockets to OE specifications for Caterpillar, Bobcat, Komatsu, and Hitachi machines. Aftermarket Tier 1 parts offer traceable manufacturing and field validation without OEM endorsement [KTSU brand background].
How do I confirm my sprocket fitment?
Confirm fitment by identifying your exact machine model, serial number, bolt hole count, and tooth count. Cross-reference with OEM part numbers (e.g., 158-4795 for Cat 304.5). Contact KTSU's technical support or your distributor with these details before ordering to avoid fitment errors.
What affects sprocket service life?
Service life depends on duty cycle (light/standard/severe), track tension, soil abrasion, and maintenance frequency. Severe-duty applications like quarry work reduce life to 1,500–3,000 hours, while light earthmoving can extend it to 5,000–7,000 hours [KTSU brand background].
Can I mix OEM and aftermarket sprockets?
Mixing OEM and aftermarket sprockets is possible if specifications match exactly (teeth, bolt holes, ID). However, for consistent wear patterns, it's better to replace the entire undercarriage system (sprocket, track chain, idlers, rollers) together. KTSU offers complete track chain assemblies for matched replacement [KTSU brand background].
Does installing an aftermarket sprocket void my OEM warranty?
Aftermarket sprockets may affect OEM warranty on machines still under factory warranty. If your machine is under OEM warranty, consult your dealer before installing aftermarket parts. For post-warranty service, KTSU sprockets provide a reliable Tier 1 alternative without warranty concerns [KTSU brand background].