The Multiquip 21508-001 Engine Assembly JD4020TF-005 55HP is a genuine OEM power unit designed for STX55Y6 and STX55J6 super-sized hydrostatic ride-on trowels. This is an exact-match replacement sourced directly through Multiquip, ensuring the assembly meets the original engineering specifications for the STX55 series. With a 55HP output rating, this engine assembly delivers the power needed to drive the hydraulic systems that control both blade pitch and machine travel on these large-format trowels. DHS Equipment supplies this part as a fully authorized Multiquip OEM replacement, giving buyers confidence in fitment and quality from the first installation.
Key Features
- Genuine OEM Engine Assembly — Sourced directly through Multiquip to meet the original power and torque output specifications required by the STX55 hydrostatic trowel platform.
- 55HP Rated Output — Delivers the full power capacity needed to sustain hydraulic pressure across blade pitch adjustment and drive functions simultaneously under load.
- Direct-Fit Replacement for STX55 Series — Engineered to drop into STX55Y6 and STX55J6 machines with correct mounting geometry and interface points for the existing hydraulic and electrical connections.
- Hydrostatic System Compatibility — Matched to the hydraulic drive demands of the STX super-sized series, where engine output directly governs finishing consistency and operator control response.
- Fuel System Safety Assurance — As a complete engine assembly, using a verified OEM unit ensures fuel, ignition, and exhaust configurations comply with the machine's original safety and emissions design.
The engine assembly is the primary power source for the STX55 hydrostatic ride-on trowel, converting fuel into mechanical energy that feeds the machine's hydraulic system. On hydrostatic trowels, the engine does not directly spin the blades — it drives hydraulic pumps that control both blade pitch and machine propulsion, meaning any drop in engine output directly affects finishing quality and operator control. A worn, damaged, or incorrect engine assembly can result in sluggish hydraulic response, inconsistent blade speed, or complete loss of drive function, making a correct OEM replacement critical to restoring full machine performance.
Part Details
| Part Number | 21508 |
|---|---|
| Brand | Multiquip |
| Part Type | Genuine OEM |
| Description | Engine Assembly JD4020TF-005 55HP |
Compatibility & Fitment
| Name | Model |
|---|---|
| Whiteman Ride-On Power Trowels | STX55Y6 |
| Whiteman Ride-On Power Trowels | STX55J6 |
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.
