The Multiquip 21583-001 is a genuine OEM HHC Screw 5/16-24 x 1-1/2 Grd 8 designed for HTX44 and STX55 series Whiteman ride-on power trowels. As a Grade 8 fastener, this screw meets the tensile and torque specifications required for the high-vibration, high-load environment of hydrostatic ride-on trowel operation. Sourced directly from Multiquip, it is an exact match to the hardware installed at the factory and confirms correct fitment for HTX44K4, HTX44K5, HTX44Y4, HTX44Y5, STX55J6, and STX55Y6 models. Keeping the correct grade and thread specification on hand means faster, accurate service when hardware needs replacement.
Key Features
- Grade 8 Tensile Strength — Rated for the elevated clamping loads and vibration exposure found throughout HTX44 and STX55 ride-on trowel assemblies.
- Exact Thread Specification — 5/16-24 fine-thread pitch matches the threaded interfaces on these machines precisely, ensuring full thread engagement without chasing or rework.
- Genuine OEM Sourcing — Supplied directly by Multiquip, this fastener carries the same part number and material grade as the original hardware used in production.
- Broad HTX44 and STX55 Coverage — Confirmed fitment across HTX44K4, HTX44K5, HTX44Y4, HTX44Y5, STX55J6, and STX55Y6 models, covering Kubota and Yanmar-powered variants in both series.
- Critical Structural Integrity — Using the correct grade fastener in load-bearing trowel applications prevents joint loosening, hardware failure, and potential damage to surrounding components during operation.
A hex head cap screw is a structural fastener used to clamp two or more components together under a specified torque load. In ride-on power trowels like the HTX44 and STX55, Grade 8 screws are specified in locations where high tensile strength and resistance to loosening under vibration are essential — such as blade assembly brackets, drive components, and frame-mounted hardware. Using an undersized or lower-grade substitute in these positions risks fastener stretch, loosening, or shear failure during operation, which can lead to component separation and machine damage. Replacing worn or damaged hardware with the correct OEM-specified 21583-001 restores the joint to its original engineered clamping specification.
Part Details
| Part Number | 21583 |
|---|---|
| Brand | Multiquip |
| Part Type | Genuine OEM |
| Description | HHC Screw 5/16-24 x 1-1/2 Grd 8 |
Compatibility & Fitment
| Name | Model |
|---|---|
| Whiteman Ride-On Power Trowels | HTX44K4 |
| Whiteman Ride-On Power Trowels | HTX44K5 |
| Whiteman Ride-On Power Trowels | HTX44Y5 |
| Whiteman Ride-On Power Trowels | HTX44Y4 |
| 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.
