This maintenance manual provides comprehensive instructions for the AxleTech Dura-Disc WDH-Series Wet Disc Brakes, covering models with 330mm, 432mm, and 560mm housing diameters . These hydraulically actuated friction brakes are designed for heavy-duty applications and utilize either sump or forced cooling systems to manage heat during operation.

Core Maintenance Procedures

1. Coolant Management

Coolant must be changed after the first month (200-250 hours) of operation and every six months (3,000 hours) thereafter .

Sump Systems: Use the lubricant in the housing as coolant. The operating temperature must never exceed 250°F (120°C) to avoid internal damage .
Forced Systems: Use a pump and reservoir to circulate fluid. When refilling, the housing cover plug must be loosened to bleed air until coolant leaks out .

2. Disassembly & Service

Piston Removal: Requires a lifting device and eye bolts; technicians must be careful not to damage the housing or piston surfaces .
Safety Warning: The piston return spring assemblies are under high pressure. A press must be used to slowly release the spring tension to prevent injury .
Parts Preparation: Ground and polished parts must be cleaned with solvent (kerosene or diesel), never water or steam .

3. Assembly & Leak Testing

Disc Pack: Discs must be installed in a specific alternating order (stationary, then friction), ensuring a stationary disc is always the last one installed .
Sealing: Silicone (RTV) gasket material must be applied in a 1/8 inch (3.0 mm) bead around fastener holes.
Hydraulic Testing: After assembly, the unit should be pressurized to 2000-2200 psi at least five times and held for one minute to verify there are no leaks .

Technical Specifications

Component	Torque Specification
Hydraulic Inlet Fitting	60-75 lb-ft (81-102 N·m)
Cover-to-Housing Capscrew	627-811 lb-ft (850-1100 N·m)
Magnetic Drain Plugs	20 lb-ft (27 N·m) Minimum
Bleeder Screw	15-20 lb-ft (20-27 N·m)