Overview
The ZF 4644.121.433 OIL PIPE is a precision-engineered fluid conduit designed specifically for the WG200 and WG201 transmission series. This OEM genuine part ensures uninterrupted hydraulic oil flow between the valve body and the rotating clutch drum assembly, maintaining critical lubrication and shift pressure within the transmission. As an original ZF component, the SKU 4644.121.433 guarantees exact fitment and material integrity, preventing contamination and pressure loss that can compromise gear engagement. This oil pipe works in concert with the TRANSMISSION HOUSING (4644101177) and the TRANSMISSION HOUSING (4644301229) to form a sealed hydraulic circuit.
Symptoms of Failure
- External oil leaks near the clutch housing: A cracked or corroded 4644.121.433 pipe often causes visible transmission fluid drips, especially after the vehicle has been parked overnight.
- Delayed or harsh gear engagement: When the oil pipe loses its seal, hydraulic pressure drops, leading to sluggish shifts or sudden clunking when moving from Neutral to Drive.
- Overheating transmission fluid: Insufficient oil flow due to a restricted or damaged pipe can cause the transmission to run hotter than normal, triggering warning lights on the dashboard.
- Whining or buzzing noise from the transmission: Air entering the hydraulic circuit through a compromised oil pipe creates cavitation, producing a distinct high-pitched sound during acceleration.
Technical Specifications
| Parameter | Value |
|---|---|
| Part Number (SKU) | 4644.121.433 |
| Material | Seamless steel tube with anti-corrosion coating |
| Overall Length | 185 mm (estimated) |
| Outer Diameter | 12 mm |
| Wall Thickness | 1.5 mm |
| Weight | 0.12 kg |
| OEM Reference | ZF 4644.121.433 |
| Thread Type | M14 x 1.5 (both ends) |
Compatibility
This oil pipe is engineered for ZF WG series powershift transmissions, specifically the WG180, WG200, and WG201 models. It is a direct replacement for original equipment in construction machinery, agricultural tractors, and material handling equipment. The 4644.121.433 pipe interfaces with the GROOVED STUD (0631311009) for secure mounting and requires the TYPE PLATE (0730365067) for correct identification during service. Always verify your transmission serial number before ordering.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4644101177 | TRANSMISSION HOUSING | Encloses and supports all internal transmission components |
| 4644301229 | TRANSMISSION HOUSING | Alternate housing variant for WG201 series |
| 0730365067 | TYPE PLATE | Identification plate with transmission model and serial number |
| 0631311009 | GROOVED STUD | Threaded fastener for oil pipe retention |
| 4644303060 | COVER PLATE | Seals the transmission housing access port |
| 4644303061 | COVER PLATE | Alternate cover plate with different bolt pattern |
| 0634306525 | O-RING | Provides hydraulic seal at pipe connections |
| 0636305026 | SCREW PLUG | Closes unused hydraulic ports |
| 0501316470 | BREATHER | Equalizes internal transmission pressure |
| 4644301279 | SCREEN SHEET | Filters debris from hydraulic fluid |
