The Wacker Neuson Spring Washer is a genuine OEM component designed for the APT4S and APT4T pump series, including standard and cold weather configurations. As a factory-sourced part, the is manufactured to the same specification as the original, ensuring a direct drop-in replacement with no guesswork. It covers the full APT4S and APT4T lineup — including surge brake, electric brake, skid-mounted, and cold weather variants — so you can order with confidence knowing it fits your machine. When it's time to service your pump, using the correct OEM spring washer keeps the assembly performing exactly as Wacker Neuson intended.
Key Features
- Genuine OEM Tension Integrity — Manufactured to the original spring-load specification, delivering consistent clamping force and resistance to fatigue that keeps fastened joints secure under vibration.
- Direct Drop-In Installation — Matches the original bore diameter and seat profile, seating correctly against mating hardware without shimming or modification.
- Broad APT4S and APT4T Coverage — Compatible with APT4S Pump with Skid, APT4T Pump with Surge Brake, APT4T Pump with Electric Brake, and all corresponding cold weather variants.
- Vibration-Resistant Clamping — A properly functioning spring washer prevents fastener loosening caused by pump vibration and cyclic loading; a worn or flat washer allows joint movement that can lead to leaks or component damage.
- Sourced Direct from Wacker Neuson — Part number 5100040911 is an authorized OEM part, so the material grade and geometry are identical to what left the factory originally.
A spring washer is a small but critical fastening component that sits beneath a bolt or nut to apply continuous axial tension to the joint. Its curved or split profile exerts a spring force that resists loosening caused by vibration, thermal cycling, and dynamic loads — conditions common in water pump operation. When a spring washer loses its temper, flattens, or corrodes, the fastener it supports can back out, allowing components to shift, leak, or fail prematurely.
Part Details
| Part Number | 5100040911 |
|---|---|
| Brand | Wacker Neuson |
| Part Type | Genuine OEM |
| Description | Spring Washer |
Compatibility & Fitment
| Name | Model | Machine Number |
|---|---|---|
| APT4S Pump w/Skid | APT4S | 5200018977 |
| APT4T Pump, Surge Brake | APT4T | 5200019643, 5200019644 |
| APT4T Pump, Surge Brake, Cold Weather | APT4T CW | 5200019792, 5200019793 |
| APT4S Pump w/Skid, Cold Weather | APT4S CW | 5200019798 |
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.
