Overview
The ZF 4644.026.277 WENDEGETRIEBE Powershift Transmission Assembly is a complete, factory-sealed unit designed for heavy-duty directional shifting in industrial drivetrains. As a core component of the WG 200 Series, this assembly integrates the forward-reverse clutch pack, hydraulic control valve body, and output shaft housing into a single, ready-to-install module. The SKU 4644.026.277 specifically denotes a fully assembled “Wendegetriebe” (reversing gearbox) that manages torque flow during shuttle operations, eliminating the need for manual clutch engagement. This unit sits directly between the engine flywheel housing and the main transmission casing, acting as the primary interface for load-reversal under power.
Symptoms of Failure
When the ZF 4644.026.277 begins to degrade, operators will notice distinct operational issues. Recognizing these signs early can prevent catastrophic drivetrain damage.
- Delayed or Harsh Directional Shifts: A pronounced lag when shifting from forward to reverse, or a violent “clunk” during engagement, indicates worn clutch discs or degraded hydraulic seals inside the assembly.
- Internal Hydraulic Leaks at the Housing Seam: Oil weeping from the mating surface between the Wendegetriebe and the main transmission casing is a common failure point, often caused by a compromised O-ring or gasket under high backpressure.
- Loss of Power Under Load in Reverse: If the machine struggles to maintain torque when backing up a grade, the reversing clutch pack within the 4644.026.277 may be slipping due to burnt friction material or a stuck piston.
- Erratic Neutral Engagement: The transmission fails to fully disengage when the shuttle lever is in neutral, causing creep. This points to valve body sticking or residual pressure in the Wendegetriebe circuit.
Technical Specifications
| Specification | Value |
|---|---|
| Assembly Type | Complete Powershift Reversing Unit (Wendegetriebe) |
| OEM Reference | ZF 4644.026.277 |
| Overall Length | 385 mm (15.2 in) |
| Housing Diameter | 320 mm (12.6 in) |
| Dry Weight | 47.5 kg (104.7 lbs) |
| Housing Material | High-Grade Cast Iron (GGG-40) |
| Clutch Disc Material | Sintered Bronze on Steel |
| Max Input Torque | 1,200 Nm (885 lb-ft) |
| Hydraulic Pressure Range | 14-18 bar (203-261 psi) |
Compatibility
This ZF 4644.026.277 complete unit is engineered for the WG 200 Series of powershift transmissions. It is directly compatible with the following ZF transmission models and their derivatives:
- ZF WG 180 (4-speed and 6-speed variants)
- ZF WG 200 (all sub-variants including WG 200/2 and WG 200/4)
- ZF WG 210 (when used with specific bellhousing adapters)
- ZF WG 220 (early production models with standard clutch pack spacing)
This assembly is not compatible with the WG 150 series or any Ecoshift models without significant hydraulic circuit modifications. Always verify the input spline count and housing bolt pattern against your existing unit before installation.
