Overview
The ZF 4644.306.262 PISTON is a critical hydraulic actuation component engineered for the WG 180 and WG 200 series transmissions. This OEM genuine part functions as a pressure-responsive plunger within the clutch pack or shift valve body assembly, converting hydraulic fluid force into precise mechanical movement to engage or disengage gear sets. The SKU 4644.306.262 is manufactured to exacting ZF tolerances, ensuring consistent sealing and stroke length under high thermal loads. When installed, this piston works in direct conjunction with the 4642101109: TRANSMISSION HOUSING and the 4642301205: TRANSMISSION HOUSING, which provide the sealed bore environment necessary for proper piston travel and pressure containment.
Symptoms of Failure
- Delayed or harsh gear engagement: A worn 4644.306.262 piston often causes a noticeable lag when shifting from Neutral to Drive or Reverse, followed by an abrupt clutch application.
- Intermittent transmission slipping under load: As the piston loses its sealing edge, hydraulic pressure bleeds past the component, leading to clutch pack slippage during acceleration or hill climbing.
- Low hydraulic pressure codes or erratic shift patterns: Internal leakage past a degraded piston can trigger diagnostic trouble codes (DTCs) related to insufficient line pressure, causing the transmission to hunt between gears.
- Visible oil contamination in the valve body area: Cracks or scoring on the piston surface allow ATF to bypass, often resulting in burnt-smelling fluid or metallic debris in the pan.
Technical Specifications
| Parameter | Specification |
|---|---|
| Part Number | 4644.306.262 |
| Material | Hardened aluminum alloy with anodized surface |
| Outer Diameter | 38.5 mm (estimated) |
| Overall Length | 42.0 mm (estimated) |
| Weight | 0.085 kg (estimated) |
| OEM Reference | ZF 4644.306.262 (Genuine) |
| Seal Type | Integrated PTFE lip seal |
Compatibility
This piston is specifically designed for ZF WG-series powershift transmissions. Verified compatibility includes the WG 180 and WG 200 series, as well as the WG 100, WG 150, and WG 201 series where the same hydraulic circuit architecture is employed. It is commonly used in construction equipment, agricultural tractors, and material handling machinery. For proper installation, ensure the 0730365125: TYPE PLATE is referenced to confirm transmission model identification, and verify that the 0631311009: GROOVED STUD is torqued correctly to secure the piston bore cover.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4642101109 | TRANSMISSION HOUSING | Encloses the piston bore and gear train |
| 4642301205 | TRANSMISSION HOUSING | Secondary housing for valve body support |
| 0730365125 | TYPE PLATE | Identification plate for transmission model |
| 0631311009 | GROOVED STUD | Fastener for piston bore cover |
| 4642301168 | SCREEN SHEET | Filter screen for hydraulic circuit |
| 4642301169 | SCREEN SHEET | Secondary filter screen |
| 0636100621 | HEXAGON SCREW | Mounting screw for housing assembly |
| 4642301186 | SCREEN SHEET | Fine mesh screen for oil return |
| 4644106231 | SHIFT SYSTEM | Complete shift control assembly |
| 4644306470 | GASKET | Seal between housing and valve body |
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