Overview
The ZF 4699.109.026 BRAKE UNIT is a critical hydraulic-mechanical assembly designed to manage torque interruption and rotational deceleration within heavy-duty ZF powershift transmissions. Positioned directly on the output shaft housing, this OEM genuine part integrates the friction discs, piston, and return springs necessary for controlled braking during machine operation. The SKU 4699.109.026 is engineered to withstand extreme thermal loads and high-pressure cycles common in construction machinery, ensuring consistent stopping force under load. This brake unit interfaces directly with the 4699101025: HOUSING and the 4699301078: HOUSING to form a sealed, pressurized chamber that prevents contamination ingress while maintaining precise clutch-pack clearance.
Symptoms of Failure
- Delayed braking response or “soft pedal” condition: When the internal piston seals wear, hydraulic pressure bleeds past the O-rings, causing a spongy feel during deceleration. This often manifests as a lag between lever input and actual machine slowdown.
- Transmission oil contamination with friction material: Worn brake discs shed particulate debris into the hydraulic circuit. Operators may notice dark, metallic-smelling fluid during routine sampling, often accompanied by erratic shift quality.
- External oil seepage at the housing joint: Degraded shaft seals or housing gaskets allow ATF to weep from the brake unit interface. Look for wet spots near the 4699301015: HOUSING COVER or the 4699301085: COVER.
- Audible grinding or chattering during engagement: Worn return springs or warped friction plates produce a distinct metallic noise when the brake is applied under load, indicating imminent mechanical failure.
Technical Specifications
| Parameter | Value |
|---|---|
| Part Number | 4699.109.026 |
| Component Type | Brake Unit (Disc Pack Assembly) |
| Outer Diameter | 210 mm (est.) |
| Overall Height | 85 mm (est.) |
| Dry Weight | 3.2 kg (est.) |
| Primary Material | Steel friction discs with sintered bronze lining |
| OEM Reference | ZF 4699.109.026 |
| Operating Pressure | 12-18 bar |
| Temperature Range | -20°C to +120°C |
Compatibility
This brake unit is primarily specified for ZF WG180 and WG200 series powershift transmissions used in wheel loaders, telehandlers, and backhoe loaders. It also fits select variants of the ZF WG150 and WG310 models where the output brake assembly shares the same spline count and piston bore dimensions. Always verify the housing casting number against the 4699101025: HOUSING to confirm fitment before installation.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4699101025 | HOUSING | Encloses brake unit and supports output shaft |
| 4699301078 | HOUSING | Secondary housing for clutch pack retention |
| 4699301015 | HOUSING COVER | Seals the brake chamber and guides piston |
| 4699301085 | COVER | External cover protecting adjustment mechanism |
| 4699301014 | THREAD PROTECTIVE SHIELD | Prevents thread damage during assembly |
| 0634303980 | O-RING | Hydraulic seal between housing and cover |
| 0734307407 | PROTECTION CAP | Dust cap for hydraulic port |
| 0634319161 | SHAFT SEAL | Prevents oil leakage along output shaft |
| 0637885612 | BREATHER | Equalizes internal pressure and vents moisture |
| 0636102023 | CAP SCREW | Fastens cover to housing with specified torque |
