ZF 4139.330.409 DIAPHRAGM for WG200 | OEM Genuine Part

Overview

The ZF 4139.330.409 DIAPHRAGM is a critical sealing component engineered for the WG200 series of powershift transmissions. This OEM genuine part functions as a flexible barrier within the hydraulic control system, precisely regulating oil flow and maintaining pressure integrity between chambers. Positioned inside the valve body or clutch housing assembly, the diaphragm ensures consistent actuation of clutch packs and shift valves. The SKU 4139.330.409 is manufactured to ZF’s exacting tolerances, providing reliable performance in heavy-duty construction, mining, and agricultural equipment. When paired with a robust TRANSMISSION HOUSING or a TRANSMISSION HOUSING, this diaphragm prevents cross-contamination of hydraulic circuits, directly supporting smooth gear engagement and extended transmission life.

Symptoms of Failure

When the ZF 4139.330.409 diaphragm wears out, operators may notice these specific failure indicators:

• Hydraulic oil leaks around the valve body: A cracked or hardened diaphragm allows pressurized ATF to escape, leaving visible puddles under the transmission housing.
• Erratic or delayed gear engagement: Loss of pressure differential across the diaphragm causes clutch packs to engage slowly or slip under load, especially during cold starts.
• Intermittent transmission shuddering: Worn material cannot maintain stable oil flow, leading to vibration during shifts between forward and reverse gears.
• Overheating of transmission fluid: A failed diaphragm disrupts the cooling circuit, causing the oil temperature to rise rapidly during normal operation.

Technical Specifications

Compatibility

This diaphragm is specifically designed for the ZF WG200 series transmissions, including models WG180, WG200, and WG210. It also fits select variants of the WG150 and WG250 series when used in hydraulic control modules with identical valve body configurations. Always verify the part number against your transmission’s serial plate; the TYPE PLATE provides the exact model designation. For secure mounting, use a GROOVED STUD to fasten the diaphragm cover during reassembly.

Related Components