ZF 5838.128.001 BRAKE BOOSTER | OEM Genuine Part

Overview

The ZF 5838.128.001 BRAKE BOOSTER is a critical hydraulic assist component designed to amplify driver input force within the transmission brake circuit of heavy-duty construction machinery. Positioned between the master cylinder and the axle-mounted service brakes, this OEM genuine part ensures consistent, high-pressure fluid delivery for reliable stopping power under extreme loads. The SKU 5838.128.001 is engineered to ZF’s original tolerances, guaranteeing direct bolt-on replacement without modification. When paired with a properly maintained 5838022003: REAR AXLE and 5838109001: DIFFERENTIAL, this booster maintains the hydraulic integrity required for safe operation in excavators, wheel loaders, and graders.

Symptoms of Failure

• Spongy or low brake pedal feel: Internal seal degradation within the booster allows hydraulic fluid to bypass, resulting in a soft pedal that requires excessive travel before engagement.
• Visible hydraulic fluid leaks around the booster housing: Worn piston seals or cracked housing cause external oil seepage, often seen dripping from the bell housing or near the 5838300128: DIFFERENTIAL HOUSING.
• Intermittent brake drag or delayed release: A sticking booster piston prevents full retraction, causing the brakes to remain partially applied, leading to overheating and premature wear of the 0750117075: TAPER ROLLER BEARING.
• Increased stopping distance under load: Loss of hydraulic boost reduces clamping force at the calipers, making the machine difficult to control on slopes or during emergency stops.

Technical Specifications

Compatibility

This brake booster is primarily specified for ZF WG series powershift transmissions used in construction machinery. Based on the part type and hydraulic circuit design, the 5838.128.001 is compatible with the following transmission models: WG180, WG200, WG210, and WG250. It also integrates with certain ERGOPOWER and Ecomix drivelines. For axle-side integration, verify clearance with the 5838109001: DIFFERENTIAL and the 5838022003: REAR AXLE assembly. Always confirm your machine’s serial number against ZF’s parts catalog before ordering.

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