Overview
The ZF 4644.230.052 DIAPHRAGM for WG200 is a critical pneumatic actuation component engineered to precisely control clutch engagement and disengagement within the WG 200 series transmission. This OEM genuine part, identified by SKU 4644.230.052, functions as a flexible sealing membrane that converts air pressure into mechanical force, ensuring smooth gear shifts under heavy-duty operating conditions. Located within the transmission’s valve body assembly, this diaphragm directly interacts with the TRANSMISSION HOUSING to maintain system integrity. When paired with a properly sealed COVER PLATE, it creates a leak-proof chamber essential for consistent hydraulic response.
Symptoms of Failure
When the ZF 4644.230.052 diaphragm deteriorates, operators typically notice these specific failure modes:
- Erratic gear engagement or delayed shifting – A worn diaphragm cannot maintain consistent air pressure, causing hesitation during upshifts or downshifts under load.
- External oil seepage near the valve body – Cracks or tears in the rubber material allow transmission fluid to bypass the seal, often visible as wet spots around the TRANSMISSION HOUSING interface.
- Audible air hissing during operation – A ruptured diaphragm permits compressed air to escape, producing a distinct hissing sound that worsens with throttle application.
- Intermittent loss of drive in forward gears – Severe diaphragm failure prevents full clutch pack engagement, leading to temporary power loss that mimics transmission slipping.
Technical Specifications
| Parameter | Specification |
|---|---|
| OEM Part Number | 4644.230.052 |
| Material | Nitrile rubber (NBR) with fabric reinforcement |
| Outer Diameter | 152 mm (6.0 in) |
| Thickness | 3.2 mm (0.126 in) |
| Operating Pressure Range | 4.5 – 8.5 bar (65 – 123 psi) |
| Temperature Range | -40°C to +120°C (-40°F to +248°F) |
| Weight | 0.085 kg (0.19 lb) |
| OEM Reference | ZF 4644.230.052 (Genuine) |
Compatibility
This diaphragm is engineered for the ZF WG200 series transmission family, including the WG180, WG200, and WG210 variants used in municipal buses, fire trucks, and heavy-duty construction vehicles. It is also compatible with select ZF Ecolife models that share the same pneumatic actuation architecture. For proper sealing during installation, always replace the O-RING that seats between the diaphragm and the housing to prevent cross-threading and fluid bypass.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4644101249 | TRANSMISSION HOUSING | Encloses gear train and valve body |
| 4644301402 | TRANSMISSION HOUSING | Alternate housing variant for WG200 |
| 4644301298 | COVER PLATE | Seals diaphragm chamber |
| 0634306323 | O-RING | Prevents fluid leakage at housing joint |
| 0636305026 | SCREW PLUG | Closes hydraulic test ports |
| 4644301279 | SCREEN SHEET | Filters debris from oil flow |
| 4644301088 | SEALING CAP | Protects valve body openings |
| 4644109044 | PARKING BRAKE | Engages parking lock mechanism |
| 0501211070 | BRAKE | Service brake assembly |
| 0501317036 | PISTON | Actuates clutch pack |
