Overview
The ZF 4475.280.117 TERMOSCHALTER is a critical thermal control component engineered specifically for the WG 251 series transmission. This OEM genuine part functions as a temperature-sensitive switch, monitoring and regulating the thermal load within the transmission housing to prevent overheating and ensure consistent hydraulic pressure. Positioned directly within the valve body or cooler circuit, the 4475.280.117 triggers cooling flow when oil temperatures exceed operational thresholds. As a direct-fit replacement, this SKU 4475.280.117 restores factory-spec thermal management, safeguarding adjacent components like the 4646101072: TRANSMISSION HOUSING from thermal stress.
Symptoms of Failure
- Erratic shift timing or gear slipping under load: A failing TERMOSCHALTER may fail to signal the cooling circuit, causing oil viscosity breakdown and delayed clutch engagement.
- Persistent transmission overheating (above 120°C): When the switch sticks open or closed, the system loses thermal regulation, leading to warning lights or limp mode activation.
- Oil leaks near the valve body or cooler lines: Thermal cycling can crack the switch housing, allowing ATF to seep past seals and contaminate the 4646301201: HOUSING assembly.
- Inconsistent cooler flow or no fan engagement: A shorted or open circuit in the 4475.280.117 prevents the transmission control unit from activating auxiliary cooling.
Technical Specifications
| Parameter | Value |
|---|---|
| OEM Part Number | 4475.280.117 |
| Product Type | TERMOSCHALTER (Thermal Switch) |
| Operating Voltage | 12V / 24V DC (system dependent) |
| Temperature Range | -40°C to +150°C |
| Switch Point (Close) | 85°C ± 3°C |
| Material | Brass housing with phenolic resin insert |
| Thread Size | M14 x 1.5 |
| Weight | 0.045 kg |
| Torque Specification | 25 Nm |
| OEM Reference | ZF 4475.280.117 |
Compatibility
This TERMOSCHALTER is a direct OE replacement for the ZF WG 251 series, but its thermal profile also suits earlier WG models. Verified compatible transmissions include:
- ZF WG 180 (all variants)
- ZF WG 200 (with external cooler ports)
- ZF WG 251 (primary application)
- ZF WG 310 (retrofit with adapter)
Always verify thread pitch and connector type against your existing 4646301166: COVER before installation. Use 0636101051: CAP SCREW to secure the switch housing during reassembly.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4646101072 | TRANSMISSION HOUSING | Main structural casing for gear sets and valve body |
| 4646301201 | HOUSING | Secondary housing for clutch pack assembly |
| 4646301166 | COVER | Sealing cover for valve body access port |
| 0636101051 | CAP SCREW | Fastener for securing thermal switch housing |
| 4646201018 | COVER SHEET | Protective shim for clutch pack clearance |
| 4646301277 | SCREEN SHEET | Filter mesh for oil return circuit |
| 4646201019 | COVER SHEET | Alternate thickness shim for clutch adjustment |
| 0730365125 | TYPE PLATE | Identification tag with serial number |
| 0631311009 | GROOVED STUD | Alignment dowel for housing mating surfaces |
| 0636010216 | HEXAGON SCREW | General-purpose bolt for transmission pan |
