How Can You Add Trailer Air Brake Connections to a 2006 Mack Granite CV713

[MikePhua]

Quick Answer
To equip a 2006 Mack Granite CV713 dump truck with trailer air brake connections, you’ll need a combination of air line plumbing, gladhand fittings, control valves, and possibly a tractor protection valve. While no universal kit exists, assembling the right parts based on your truck’s configuration is straightforward.
Mack Granite CV713 Background and Brake System Design
The Mack Granite CV713 was introduced in the early 2000s as part of Mack’s heavy-duty vocational lineup. Designed for dump, mixer, and construction applications, it features a rugged chassis, high ground clearance, and a powerful Mack MP7 or ASET engine. By 2006, the CV713 had become a staple in North American fleets, known for its durability and adaptability.
The truck’s air brake system includes:

• Dual air tanks (primary and secondary)
  
• Foot valve (service brake control)
  
• Spring brake chambers for parking/emergency
  
• ABS module (on most units)
  
• Optional trailer air supply port (not always factory-installed)
  

To tow a trailer with air brakes, the truck must supply both service and emergency air through gladhand connectors mounted at the rear.
Required Components for Trailer Air Connection

• Gladhand connectors
  Standard red (emergency) and blue (service) couplers mounted on the rear crossmember or frame extension.
  
• Air lines
  DOT-approved nylon or rubber lines routed from the truck’s air system to the gladhands. Use color-coded lines for clarity.
  
• Trailer hand valve (optional)
  Also called a “trolley valve,” this allows manual trailer brake application. Useful for spot braking or testing.
  
• Tractor protection valve
  Prevents air loss from the truck if the trailer breaks away. Often integrated into the dash-mounted trailer supply valve.
  
• Trailer supply valve
  Dash-mounted red knob that controls emergency air to the trailer. Must be plumbed into the secondary tank circuit.
  
• Relay valve (if needed)
  Boosts air signal to the trailer brakes, especially on longer wheelbase trucks.
  

Installation Tips and Safety Considerations

• Use DOT-rated fittings and tubing
  Brass push-to-connect fittings are common, but ensure they’re rated for 150 psi minimum.
  
• Secure lines with clamps and grommets
  Prevent chafing and vibration damage. Avoid routing near exhaust or sharp edges.
  
• Test for leaks and pressure drop
  After installation, pressurize the system and check for leaks using soapy water. Monitor pressure stability over time.
  
• Verify brake timing and balance
  Trailer brakes should engage slightly after truck brakes. Use a brake tester or stopwatch method to confirm.
  

Field Anecdote
In Delaware, a fleet operator retrofitted his 2006 Mack Granite CV713 to haul a tag trailer with air brakes. He sourced gladhands and valves from a local truck parts supplier and used color-coded nylon lines. After installation, he noticed the trailer brakes were sluggish. A technician recommended adding a relay valve to boost signal strength. Once installed, braking performance improved dramatically, especially on downhill grades.
Recommended Parts List

• 2 gladhands (red and blue)
  
• 20–30 ft of DOT air line (red and blue)
  
• Trailer supply valve (dash mount)
  
• Tractor protection valve
  
• Relay valve (optional)
  
• Brass fittings and clamps
  
• Mounting bracket for gladhands
  

Conclusion
Adding trailer air brake connections to a 2006 Mack Granite CV713 is a practical upgrade for operators needing towing capability. While no off-the-shelf kit exists, assembling the right components and following proper plumbing practices ensures safe and reliable trailer braking. With attention to valve placement, line routing, and pressure testing, your dump truck can become a fully functional tow rig.