Trailer Components

Do Demco couplers require a safety pin?
No, Demco EZ-Latch™ couplers are designed to exceed SAE J684 safety standards without the use of a safety pin. As a result, we do not offer one. However, for anti-theft protection, we offer a locking pin (Part #16244) by Trimax, available through our distributors.

Where can I purchase Demco couplers locally?
To find a local distributor, give us a call at 800-543-3626, and our team will connect you with the nearest supplier.

Can I switch between a metal handle and a composite handle on my coupler?
Currently, Demco EZ-Latch couplers are not interchangeable between handle types. However, we are actively working to make this possible in future designs.

How do I know which repair kit fits my coupler?

• For 2” couplers, refer to page 38 of our catalog.

• For 2 5/16” couplers, refer to page 41 of our catalog.
  You can also contact Demco customer service for assistance.

Are Demco couplers adjustable?
All Demco couplers are factory-set for optimal performance. Field adjustments are not recommended unless specifically authorized by Demco.

What’s the difference between stamped and cast couplers?

• Cast couplers are made by pouring molten metal into a mold, resulting in a smooth, rounded finish.

• Stamped couplers are formed using a cold-working process, resulting in a sharper, flared edge.
  Both designs are strong, but they differ in appearance and manufacturing process.

Can I use only two bolts on a channel mount coupler?
Demco recommends using all four bolts to maintain the coupler’s full G.V.W.R. rating. Using only two bolts may reduce the rated capacity and compromise safety.

How do I bleed my hydraulic brake system?
To ensure safe and reliable braking, always use high-quality DOT-3 or DOT-4 brake fluid from a sealed container.

If using a pressure bleeder:
Follow the manufacturer's instructions for proper bleeding.

If bleeding manually:

1. Fill the master cylinder with brake fluid.

2. Attach a bleeder hose to the top bleeder screw on the first caliper. Submerge the loose end of the hose in brake fluid in a clear container to monitor for air bubbles.

3. Loosen the top bleeder screw one turn.

4. Pump the actuator with long, steady strokes. Continue until no bubbles appear in the fluid.

5. Tighten the bleeder screw securely.

6. Repeat this process at each caliper.

7. During bleeding, regularly check and refill the master cylinder to maintain at least half full.

8. Once finished, ensure the master cylinder is full and the cap is secure.

9. Pressurize the system and inspect for leaks.

Where can I purchase Demco brake components locally?
Call us at 800-543-3626 and we’ll help you locate a distributor near you.

Does your actuator come with a manual lockout option?
All of our actuators except the DA70 include or offer a manual lockout option. Specific kits are available per model.

What’s the difference between a disc and drum brake actuator?

• Disc brake actuators have a bypass solenoid on the back.

• Drum brake actuators include an additional valve in the master cylinder that controls fluid release.
  This structural difference affects how fluid is managed during braking.

Can I use a disc brake actuator with drum brakes—or vice versa?

• Yes, disc brake actuators can be used with drum brakes, though a slight braking delay may occur.

• Do not use drum brake actuators with disc brakes, as they aren’t designed to handle the fluid volume and pressure required.

What size is the fitting on the back of the master cylinder?
The fitting is 0.125” MPT x 0.188” Full Flow Inverted Flare.

My trailer brakes are locked and the emergency lever is engaged. How do I release them?
Use a flathead screwdriver to lift the front of the emergency lever spring while pulling the lever forward. This will release the locked position.

How many bolts do I need to mount my actuator?
Bolt count requirements vary by mounting style. Please contact Demco at 800-543-3626 for model-specific guidance.