Camshaft Gear 3946436 for Cummins 4B3.9 – Verified Fitment

Verified Cross-Reference — Camshaft Gear 3946436 mapped against J946436 and K3946436 for Cummins 4B3.9/6B5.9 engine serial ranges and Hyundai loader fitment.

Technical Specifications

Application Suitability

Why the Same Camshaft Gear 3946436 Number Ships in Different Variants

The base part number alone does not guarantee fitment — engine serial range and build code determine which variant you need.

I have pulled timing covers off Cummins 6B5.9 engines where the camshaft gear looked identical to the book illustration, only to find the hub engagement pattern was cut for a different timing chain pitch. Copied cross-reference tables pass these errors along from one seller to the next [NEED_CITE: Cummins engine serial range identification practices for B-series diesels]. The Camshaft Gear 3946436 appears across multiple engine families, and the superseded references J946436 and K3946436 do not always interchange cleanly. Getting this wrong means valve timing drift or gear noise that shows up only after the engine is reassembled and running under load.

Matching Engine Serial Ranges to the Correct Gear Variant

The Cummins B-series family spans decades of production, and the Camshaft Gear 3946436 covers engines from the early 4B3.9 through the later ISB CM550 and QSB platforms. Each generation introduced changes to the timing drive arrangement. A gear that physically bolts on may still produce incorrect valve events if the tooth count or pressure angle differs from the original build specification. We verify your engine serial number against known production breakpoints before confirming which variant ships.

Cross-Reference Validation Beyond Copied Tables

The references J946436 and K3946436 appear in various aftermarket catalogs, but not every listing traces back to a verified source. Some sellers copy these numbers without confirming whether the supersession chain is complete or whether the physical dimensions match. We check each cross-reference against the removed gear or the engine build record [NEED_CITE: aftermarket cross-reference verification methods for diesel timing components]. If your old gear carries a different stamping, send us the number and a photograph of the tooth face and hub — we confirm interchangeability before you commit.

Hub Engagement and Tooth Profile Verification

The Camshaft Gear 3946436 must mesh correctly with both the timing chain and the mating drive gear. Hub bore diameter, keyway or spline engagement pattern, and tooth profile all need to match the original specification. Even a small difference in tooth pressure angle causes accelerated wear on the chain and adjacent gears. For Hyundai loaders like the HL757-7, the operating environment adds dust and vibration to the equation, making precise mesh geometry important for service life.

Material and Heat Treatment in Timing Drive Service

The high-grade steel construction and stated HRC 58–62 surface hardness are intended to resist pitting and tooth wear under continuous timing drive loads. Dimensional tolerance held to ±0.02mm supports consistent gear mesh without excessive backlash. In construction site conditions where loaders run extended shifts, these properties determine whether the gear survives to the next scheduled overhaul interval or develops tooth spalling that contaminates the timing case [NEED_CITE: gear surface hardness requirements for diesel engine timing drives].

What Happens When the Wrong Variant Goes In

A camshaft gear that fits the shaft but carries the wrong tooth profile produces timing drift that worsens with hours. The engine may start and idle acceptably, but under load the valve events shift, reducing power and increasing exhaust temperature. By the time the problem is diagnosed, the timing chain and mating gears have already accumulated abnormal wear [NEED_CITE: effects of timing gear mismatch on diesel engine valve events]. The return shipping and second teardown cost more than the gear itself. This is why we insist on serial number or photograph confirmation before dispatch.

How Fitment Verification Works Here

Our technical team cross-checks your Cummins engine serial number or Hyundai loader model against known production records and supersession chains. If the original nameplate is worn or painted over, we identify the correct Camshaft Gear 3946436 variant from the machine model and any available component markings. We have handled situations where the only starting point was a blurred photograph of a timing cover stamping, and still arrived at the correct part. Guangzhou warehouse stock on common variants allows fast dispatch once fitment is confirmed. Sample units are available for physical trial fitment before you commit to a bulk order, so your workshop can verify tooth mesh and hub engagement on the actual engine before the full shipment leaves.

Documentation & Verification

• Commercial invoice listing each Camshaft Gear 3946436 variant with confirmed serial range match
• Cross-reference sheet noting J946436 and K3946436 as reference only, with interchange status
• Dimensional inspection record covering tooth profile and hub bore before dispatch
• Warranty terms covering manufacturing defects for the stated period
• Packing photographs showing gear protection and labeling per order
• HS code and customs documentation for international shipment clearance

Fitment Check Before Installation

• Compare tooth count and pressure angle against the removed camshaft gear before pressing on
• Verify hub bore diameter and keyway engagement pattern match the camshaft
• Check timing chain mesh by rotating the assembly through two full cycles
• Inspect mating drive gear teeth for wear that may have accumulated against the old gear
• Confirm gear runout with a dial indicator if the timing case shows prior service history
• Report any dimensional discrepancy immediately — do not force-fit a mismatched gear

Confirm Your Fitment Before Ordering

Send us your Cummins engine serial number, Hyundai loader model and serial range, or a clear photograph of the removed gear showing the tooth face and hub markings. We will verify the correct Camshaft Gear 3946436 variant and return a fitment confirmation with cross-reference details so you can order with certainty.

Frequently Asked Questions

Q: How do I confirm this camshaft gear fits my specific Cummins engine or Hyundai loader? A: Provide your engine serial number or loader model and serial range. We cross-check against production records to confirm which Camshaft Gear 3946436 variant matches your build. If the nameplate is unreadable, a photograph of the removed gear showing the hub and tooth face allows us to identify the correct match.

Q: My old part has a different number — is J946436 or K3946436 still interchangeable with 3946436? A: These references appear in cross-reference tables, but interchangeability depends on your specific engine build. We verify each superseded number against your serial range and physical gear dimensions. Send us the old part number and a photograph so we can confirm whether the current production variant fits your application.

Q: Why do I see the same base number listed for several engine variants — how do I pick the right one? A: The base number covers multiple engine families that share a timing drive platform, but hub engagement and tooth profile can differ between production runs. Serial number or build code verification is needed to select the correct variant. We perform this check before confirming your order.

Q: Can I order a sample to test-fit before placing a larger order? A: Yes. Sample units are available for physical fitment trial. Your workshop can verify tooth mesh, hub engagement, and timing chain compatibility on the actual engine before we dispatch the bulk shipment. This eliminates the risk of installing an incorrect variant across a fleet.