ZF 4699.309.079 BRAKE PLUNGER | OEM Genuine Part

Overview

The ZF 4699.309.079 BRAKE PLUNGER is a precision-machined hydraulic component engineered for the internal clutch and brake packs within ZF heavy-duty powershift transmissions. This OEM genuine part acts as a critical actuator, converting hydraulic pressure into mechanical force to engage or disengage the brake discs during gear changes. Located within the transmission housing assembly, the brake plunger (SKU 4699.309.079) ensures positive, slip-free braking action under extreme torque loads. For optimal sealing and alignment, this plunger is installed in conjunction with the 4699101155: HOUSING and the 4699201018: HOUSING, which provide the necessary bore support and fluid routing.

Symptoms of Failure

• Erratic gear engagement or delayed shifting: A worn brake plunger fails to apply consistent pressure, causing hesitation when selecting forward or reverse gears.
• Internal transmission oil leaks: Degraded plunger seals allow pressurized ATF to bypass, leading to visible drips from the bell housing or cooler lines.
• Clutch brake slippage under load: When the plunger cannot fully stroke, the brake pack slips during heavy digging or grading operations, generating excessive heat and burnt oil smell.
• Intermittent loss of drive in specific ranges: A sticking plunger may cause sudden loss of power in low or high range, often misdiagnosed as a valve body issue.

Technical Specifications

Compatibility

This brake plunger is designed for ZF WG series powershift transmissions commonly found in construction machinery. Estimated compatible models include the WG180, WG200, and WG210 series. It also fits select variants of the 4WG200 and 5WG200 torque converter transmissions. The plunger interfaces directly with the 4699309077: HOUSING COVER and is secured using 0636100132: TORX SCREW fasteners. Always verify your transmission model and housing bore dimensions before installation.

Related Components