The Wacker Neuson 5200021726 Square Key is a genuine OEM component designed for the APT6T and APT6S series self-priming trash pumps. This includes APT6T configurations with surge brake, electric brake, and cold weather packages, as well as APT6S pump-with-skid and cold weather variants. As a direct factory replacement, the 5200021726 ensures correct power transfer between the shaft and impeller assembly with no guesswork on sizing or fitment. Keep a spare on hand — this small but critical component is a common service item on high-cycle pump operations.
Key Features
- Genuine OEM Dimensional Accuracy — Machined to Wacker Neuson's exact width and depth tolerances, ensuring full contact engagement across the keyway without slop or play.
- Drop-In Keyway Fit — Seats directly into the existing shaft and hub keyway on APT6T and APT6S pumps, requiring only standard hand tools for installation.
- Broad APT6 Series Coverage — Compatible with APT6T (surge brake, electric brake, cold weather) and APT6S (skid-mount and cold weather) pump configurations.
- Torque Transfer Integrity — A correctly seated square key locks the impeller to the drive shaft so engine power converts cleanly into pumping output — a worn or sheared key causes impeller slip and immediate loss of flow.
- Sourced Direct from Wacker Neuson — Genuine OEM part, carrying the same part number used by authorized Wacker Neuson service centers.
A square key is a small, precision-cut block of metal that fits into a matching slot — called a keyway — machined into both the drive shaft and the hub of the impeller or pulley it drives. Its job is to transmit rotational torque from the shaft to the driven component, preventing the two from spinning independently of each other. When a square key shears or wears, the shaft continues to rotate but the impeller does not, resulting in zero pump output even though the engine is running. Replacing a failed key promptly with the correct OEM part restores full pumping capacity and prevents secondary damage to the shaft or hub keyways from metal-on-metal contact.
Part Details
| Part Number | 5200021726 |
|---|---|
| Brand | Wacker Neuson |
| Part Type | Genuine OEM |
| Description | Square Key |
Compatibility & Fitment
| Name | Model | Machine Number |
|---|---|---|
| APT6T Pump, Electric Brake | APT6T | 5200019647, 5200019646 |
| APT6T Pump, Surge Brake, Cold Weather | APT6T CW | 5200019794, 5200019795 |
| APT6S Pump w/Skid | APT6S | 5200018982 |
| APT6S Pump w/Skid, Cold Weather | APT6S CW | 5200019799 |
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.
