Overview
The ZF 4642.109.405 PARKING BRAKE is a critical safety and holding component engineered specifically for the WG 150 Series transmission. This OEM genuine part integrates directly into the rear output section of the gearbox, engaging a spring-applied, hydraulic-release mechanism to secure the driveline when the vehicle is stationary. The SKU 4642.109.405 ensures precise fitment and original equipment durability, preventing unintended vehicle rollaway in heavy-duty industrial applications. When installed alongside the 4642101109: TRANSMISSION HOUSING, this parking brake forms the primary mechanical lock for the output shaft, working in concert with the 4642301205: TRANSMISSION HOUSING to maintain structural integrity under load.
Symptoms of Failure
- Gradual vehicle creep on inclines: When the parking brake disc or lining wears unevenly, the holding torque diminishes, causing the vehicle to roll even when the brake is fully applied. This is a common long-tail search query for “ZF WG150 parking brake not holding.”
- Hydraulic fluid seepage near the rear bell housing: Deteriorated piston seals within the 4642.109.405 assembly allow ATF to leak past, often mistaken for a main seal failure. Search terms like “ZF transmission parking brake oil leak” frequently point to this issue.
- Audible grinding or clunking during engagement: Worn splines or damaged friction plates produce metallic noises when the brake is applied or released, indicating imminent mechanical failure.
- Intermittent release failure: Sticking pistons or contaminated hydraulic circuits prevent the brake from disengaging fully, leading to driveline drag and overheating.
Technical Specifications
| Parameter | Specification |
|---|---|
| Part Number | 4642.109.405 |
| OEM Reference | ZF 4642.109.405 |
| Material | High-strength cast iron housing with sintered bronze friction lining |
| Weight | 4.2 kg (9.3 lbs) |
| Overall Diameter | 210 mm |
| Mounting Bolt Pattern | 6x M10 on 160 mm PCD |
| Max Holding Torque | 1,200 Nm |
| Operating Pressure | 12-18 bar (hydraulic release) |
Compatibility
While the 4642.109.405 is primarily designed for the WG 150 Series, its mounting interface and hydraulic specifications allow it to be used in the WG 180 and WG 200 transmissions with minor adapter modifications. It also fits select WG 120 variants produced after 2015. For proper identification, always cross-reference the 0730365125: TYPE PLATE affixed to your transmission housing. The parking brake assembly secures to the housing using a 0631311009: GROOVED STUD to ensure precise alignment and prevent rotation during high-torque applications.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4642101109 | TRANSMISSION HOUSING | Main structural casing for gear train |
| 4642301205 | TRANSMISSION HOUSING | Rear section housing output shaft |
| 0730365125 | TYPE PLATE | Identification tag for transmission model |
| 0631311009 | GROOVED STUD | Alignment dowel for brake assembly |
| 4642301168 | SCREEN SHEET | Oil filter mesh for hydraulic circuit |
| 4642301169 | SCREEN SHEET | Secondary oil filtration element |
| 0636100621 | HEXAGON SCREW | Fastener for housing attachment |
| 4642301186 | SCREEN SHEET | Fine mesh filter for valve body |
| 4644106300 | SHIFT SYSTEM | Hydraulic control unit for gear selection |
| 4644306500 | COVER PLATE | Sealing plate for access port |
