The Wacker Neuson Rocker Arm Shaft is a genuine OEM component designed for the APT4S and APT4T pump series, including standard, cold weather, surge brake, and electric brake configurations. As a factory-sourced part, the is built to the same specification as the original, ensuring a direct fit with no guesswork at installation. Compatible across six confirmed model configurations — from the APT4S Pump with Skid to the APT4T cold weather variants — this shaft covers a wide range of Wacker Neuson diaphragm pump builds. When the rocker arm shaft wears or fails, sourcing the correct OEM replacement is critical to restoring full pump operation and protecting surrounding valve train components.
Key Features
- OEM-Spec Surface Hardness — Manufactured to Wacker Neuson's original hardness and dimensional tolerances, so the shaft maintains proper bearing contact and resists accelerated wear in the rocker arm assembly.
- Drop-In Shaft Replacement — Matches the original shaft diameter and length exactly, seating correctly in the rocker arm bores without machining or shimming.
- Broad APT Series Coverage — Confirmed fit across APT4S and APT4T pump configurations, including standard, electric brake, surge brake, and cold weather models.
- Protects Valve Train Integrity — A correctly dimensioned rocker arm shaft keeps rocker movement aligned and consistent, preventing side-load stress on valves and premature wear on adjacent components.
- Genuine Wacker Neuson Part — Sourced directly from Wacker Neuson, carrying the same part number (5200019886) used by authorized service centers for pump overhauls and scheduled maintenance.
The rocker arm shaft is the pivot point around which the rocker arms oscillate, converting rotational input into the reciprocating motion that drives the pump's diaphragm. It carries the full mechanical load of each pumping stroke, so consistent geometry and surface finish are essential — a worn or undersized shaft introduces slop into the rocker movement, which reduces flow efficiency and can cause erratic pressure output. Left unaddressed, a failing rocker arm shaft accelerates wear on the rocker arms themselves and can lead to diaphragm damage, making timely replacement the most cost-effective course of action.
Part Details
| Part Number | 5200019886 |
|---|---|
| Brand | Wacker Neuson |
| Part Type | Genuine OEM |
| Description | Rocker Arm Shaft |
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.
