The Wacker Neuson 5200021639 is a genuine OEM Lock Nut designed for the APT4S and APT4T pump series. This includes the APT4S Pump w/Skid, APT4T Pump with Electric Brake, APT4T Pump with Surge Brake, and all corresponding Cold Weather variants. As a direct OEM replacement, the 5200021639 is manufactured to the same specifications as the original hardware, ensuring proper thread engagement and correct clamping force wherever it is installed. Confirm your machine's model and machine number before ordering to guarantee an accurate match.
Key Features
- Genuine OEM Thread Specification — Manufactured to the exact thread pitch and hardness grade of the original, ensuring full engagement and correct torque retention on APT4S and APT4T pump assemblies.
- Drop-In Hardware Replacement — Matches the original fastener profile and seating dimensions, threading directly into the factory position without rework or modification to the surrounding components.
- Broad APT Series Coverage — Compatible with APT4S Pump w/Skid, APT4T Pump with Electric Brake, APT4T Pump with Surge Brake, and all Cold Weather variants of each configuration.
- Secure Clamping Under Load — A properly torqued lock nut maintains component position under vibration and operational stress; a worn or missing lock nut can allow fastened assemblies to loosen and shift during pump operation.
- Critical Retention in Fuel and Fluid System Applications — On pump equipment, fastener integrity directly affects the security of fluid-carrying components; using a correctly spec'd OEM lock nut supports leak-free, stable assembly.
A lock nut is a hardened fastener engineered to resist loosening under vibration and dynamic loads — conditions that are common during pump operation. Unlike a standard nut, the locking feature (whether a nylon insert, deformed thread, or prevailing-torque design) grips the mating threads and holds the assembly in place even as the machine cycles through pressure changes and movement. When a lock nut fails, strips, or goes missing, the components it secures can shift or separate, leading to misalignment, leaks, or component damage. Replacing a worn or damaged lock nut with the correct OEM part is a straightforward service step that restores the integrity of the fastened joint.
Part Details
| Part Number | 5200021639 |
|---|---|
| Brand | Wacker Neuson |
| Part Type | Genuine OEM |
| Description | Lock Nut |
Compatibility & Fitment
| Name | Model | Machine Number |
|---|---|---|
| APT4S Pump w/Skid | APT4S | 5200018977 |
| APT4T Pump, Electric Brake | APT4T | 5200019644, 5200019643 |
| APT4S Pump w/Skid, Cold Weather | APT4S CW | 5200019798 |
| APT4T Pump, Electric Brake, Cold Weather | APT4T CW | 5200019793, 5200019792 |
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.
