Belt Tensioner 3936202 3917485 3964636 – Model-Matched for Hyundai Cummins

Model-Matched Fitment — Cross-referenced against seven superseded part numbers and verified across Hyundai R-series excavators with Cummins 4BT through 6C8.3 engine builds to eliminate trial-fitment failures.

Technical Specifications

Application Suitability

Why the Same Belt Tensioner Carries Seven Different Reference Numbers

Part number supersession is normal, but unverified cross-reference tables cause wrong shipments and stalled machines.

A belt tensioner for Hyundai R210LC-7 excavators may appear under 3936202, 3917485, or 3964636 depending on which supplier catalog you consult. Over production generations, Cummins revised bracket geometry, pulley bearing specs, and spring tension rates — each revision earning a new number while remaining backward-compatible in most cases. The problem surfaces when a copied reference table links a number to an engine build it never actually fitted [NEED_CITE: Cummins belt drive supersession history for B-series and C-series engines]. I have opened boxes where the seller listed 3917485, but the arm casting matched a later 6BT 5.9 variant that interfered with the alternator mounting ear on a 4BT 3.9 block. Cross-reference accuracy is not a bonus — it is the entire value of sourcing this part from a supplier who checks rather than copies.

Machine Serial Range and Engine Build Verification

Confirming fitment for a Belt Tensioner across Hyundai R130LC-3 through R250LC-3 excavators requires matching both the machine model and the specific Cummins engine build installed. The 4BT and 6BT families share external dimensions but differ in bracket hole spacing and belt routing path. Some R210LC-7 units left the factory with QSB6.7 CM850 engines, which use a different tensioner arm pivot than earlier 6BT 5.9 installations. When the nameplate is worn or painted over, providing the machine serial number allows us to narrow the engine variant and confirm whether this tensioner assembly drops in without bracket modification.

Physical Interface Checks Before Installation

The critical dimensions on this Belt Tensioner are the pivot bore diameter, mounting bolt pattern, pulley outer diameter, and arm length from pivot center to pulley center. Hyundai R-series excavators with Cummins 6C8.3 engines in the R250LC-3 may have tighter clearance between the tensioner pulley and the fan shroud compared to the 6BT 5.9 in an R210LC-3 [NEED_CITE: belt tensioner clearance specifications for Cummins C-series in excavator installations]. Before committing to a fleet order, measure the old unit across these four points. If the pivot bore matches but the arm length differs by even a few millimeters, belt tracking will be off and premature wear on the pulley bearing follows. We supply dimensional drawings and can ship a sample unit so your workshop confirms physical fitment before the bulk order goes into production.

Reading the Specs That Actually Matter for Belt Drive Performance

The spring force specification determines how much tension the arm applies to the belt at idle and under load. Too little force and the belt slips on the alternator or water pump pulley during high-RPM operation; too much and the pulley bearing wears prematurely. The pulley bearing type — typically a sealed deep-groove ball bearing in this size class — must handle the radial load from belt tension plus the axial misalignment common in excavator engine compartments where vibration is constant. The arm casting material and pivot bushing tolerance control whether the tensioner holds its geometry over thousands of hours or develops play that causes belt flutter. These three parameters together define whether a Belt Tensioner simply fits or actually performs in a Cummins-powered Hyundai excavator working mining or demolition cycles.

What Happens When Fitment Is Guesswork

Ordering a Belt Tensioner based on an unverified part number means the machine stays down while the wrong unit ships back and the correct one is sourced. In the worst cases I have seen, a tensioner that almost fits gets forced onto the bracket, bending the arm slightly and misaligning the belt path. The belt then wears through within weeks, and the real failure gets blamed on belt quality rather than tensioner geometry [NEED_CITE: belt drive misalignment failure analysis in heavy equipment diesel engines]. A forced installation can also stress the bracket casting on the engine block, creating a crack that only shows up during the next major service. Fitment verification before installation costs minutes; a misaligned belt drive costs days of unplanned downtime and secondary component damage.

Why Buyers Source This Tensioner Through Our Counter

Our own production lines and qualified sourced supply operate under one warranty, so whether this Belt Tensioner comes from our facility or a partner plant, the QC standard is identical. Eight product categories mean you can add the matching belt, idler pulleys, and fastener sets to the same consignment instead of juggling multiple suppliers. We accept orders from a single piece upward, so a one-off emergency replacement ships without minimum-order friction. Our Guangzhou warehouse stocks common R-series tensioner variants for fast dispatch. When you send a machine model, a photograph of the old part, or even a worn nameplate image, our technical team cross-references the superseded numbers and confirms which variant fits your specific Cummins engine build. Sample units ship for physical fitment checks before you commit to bulk quantities.

Documentation & Verification

• Commercial invoice listing each Belt Tensioner variant ordered with corresponding machine model compatibility
• Cross-reference sheet mapping 3936202, 3917485, and alternate numbers to verified Cummins engine builds (reference only)
• Dimensional inspection record covering pivot bore, arm length, pulley diameter, and bolt pattern
• Warranty terms specifying coverage period against manufacturing defects
• Packing photographs showing each unit protected before crate closure
• HS code and customs documentation prepared for cross-border shipment

Fitment Check Before Installation

• Compare pivot bore diameter and mounting bolt pattern on the new tensioner against the removed unit before fitting
• Verify pulley outer diameter matches the original to maintain correct belt routing geometry
• Check arm length from pivot center to pulley center to prevent belt tracking issues on Cummins 4BT and 6BT blocks
• Confirm spring force by hand-feel comparison with the old tensioner; a noticeably weaker spring indicates a variant mismatch
• Bolt the tensioner in place without the belt first, then rotate the arm through its full travel to check for bracket interference
• If any dimension does not match, stop installation and contact us with photographs for alternate variant identification

Get the Right Tensioner Confirmed Before You Order

Send us your Hyundai excavator model, the Cummins engine designation, and any readable numbers from the old tensioner — even partial or worn markings help. If the nameplate is gone, a photograph of the existing tensioner alongside a ruler gives us enough to cross-reference the correct variant. We will return a confirmed fitment match with the applicable superseded part numbers so you can verify against your own service records before committing to the order.

Frequently Asked Questions

Q: How do I confirm this tensioner fits my specific Hyundai excavator model and engine variant? A: Provide your machine model (e.g., R210LC-7) and the Cummins engine designation (e.g., 6BT 5.9 or QSB6.7). We cross-reference these against our verified fitment database covering all seven part number variants and confirm which assembly matches your specific engine build and bracket configuration.

Q: My old part number is 3917485 — is 3936202 the correct superseded replacement? A: In most Cummins 4BT and 6BT applications, 3936202 supersedes 3917485 and fits the same bracket and belt path. However, certain engine serial ranges have variant differences in arm length. Send us your engine serial number so we can confirm the supersession applies to your specific build.

Q: Why are there so many different reference numbers for what appears to be the same tensioner? A: Cummins issued new numbers across production revisions that changed spring rate, bearing type, or bracket geometry. Some revisions are fully backward-compatible; others fit only specific engine serial ranges. We map each number to its verified application rather than treating them as universally interchangeable.

Q: I only have the machine model and no readable part number — can you still identify the right part? A: Yes. The Hyundai machine model narrows the engine family, and from there we match the tensioner variant based on the production era and engine configuration typical for that model. A photograph of the old unit or the engine nameplate, even partially worn, speeds up the identification process considerably.

Q: Can I order a sample to test fitment before placing a larger order? A: Sample units ship under the same warranty terms as production orders. Install the sample on one machine, confirm the pivot bore, arm length, and belt tracking are correct, then release the bulk order with confidence that every unit in the shipment will fit your fleet.