The Multiquip 21921 Flywheel Coupler Assembly is a genuine OEM component designed for the HTX44Y4, HTX44Y5, STX55J6, and STX55Y6 hydrostatic ride-on power trowels. Sourced directly from Multiquip, this assembly ensures the correct fit and engagement characteristics these machines require to transfer engine power reliably. Confirm your trowel's model code before ordering to ensure compatibility with your specific unit.
Key Features
- Genuine OEM Construction — Manufactured to Multiquip's exact dimensional and material tolerances, ensuring correct torque transfer geometry for hydrostatic trowel drivetrains.
- Direct-Fit Replacement — Engineered to bolt directly to the flywheel on compatible STX and HTX Yanmar-powered trowels, aligning with the existing drive interface without modification.
- Broad STX and HTX Compatibility — Confirmed fitment for HTX44Y4, HTX44Y5, STX55J6, and STX55Y6 ride-on power trowels.
- Drivetrain Integrity — A properly functioning flywheel coupler maintains smooth, consistent power transfer from the engine to the trowel's hydraulic drive system; a worn or damaged coupler introduces vibration, slippage, and accelerated wear across downstream components.
- Correct OEM Part Number — Ordering by Multiquip part number 21921 ensures you receive the exact assembly specified for your machine, eliminating guesswork on interchangeable variants.
The flywheel coupler assembly connects the engine's flywheel to the drive system of the trowel, transmitting rotational power from the engine into the machine's hydraulic or mechanical drivetrain. It acts as the critical link between engine output and machine movement, and any wear, cracking, or misalignment in this component will disrupt power delivery — resulting in erratic trowel behavior, vibration, or a complete loss of drive. Keeping this assembly in sound condition is essential to maintaining consistent finishing performance on the slab.
Part Details
| Part Number | 21921 |
|---|---|
| Brand | Multiquip |
| Part Type | Genuine OEM |
| Description | Flywheel Coupler Assembly |
Compatibility & Fitment
| Name | Model |
|---|---|
| Whiteman Ride-On Power Trowels | HTX44Y4 |
| Whiteman Ride-On Power Trowels | HTX44Y5 |
| Whiteman Ride-On Power Trowels | STX55J6 |
| Whiteman Ride-On Power Trowels | STX55Y6 |
Verify Before You Order
Fitment is machine-number and revision-specific; always confirm your model and serial number against the fitment list.
Why Buy From DHS Equipment
Every part is verified against the manufacturer's part number before it ships, so what you order is what arrives. We carry parts from leading OEM brands and our own DHS Quality Parts line of professional aftermarket components. Need help finding the right part? Our team is available to confirm compatibility whenever you need it. Orders are processed fast to keep your jobs on track. We don't just sell parts. We keep you jobsite ready.
Questions? Contact our team at [email protected] or 866-611-9369 — DHS Equipment is here to help you maintain peak performance.
