The Demco Air Force One is a supplemental braking system designed for use with diesel motorhomes equipped with air brakes. It operates by utilizing air from the coach’s air brake system to activate the towed vehicle’s power brakes, providing proportionate braking force. The system is designed for “hidden” installation and aims to provide a seamless towing experience without requiring setup or adjustments each time a vehicle is towed. It is noted as being DOT legal and designed to protect the coach’s air supply in the event of a disconnection.
System Overview and Operation
The Air Force One system is designed to apply proportionate braking effort in the towed vehicle, mirroring the braking action of the motorhome. This is achieved by using air from the coach’s air brake system to create a vacuum in the towed vehicle’s power brake system, thereby energizing the power brakes without requiring an electronic pump. The system does not rely on moving parts or circuit boards, which contributes to its reliability.
The system consists of several key components and air line connections. One air supply line connects to the air supply for the rear brakes on the coach, feeding a small reservoir tank with a flow restriction. A second, smaller air line connects to the signal line at the rear relay valve, originating from the treadle valve at the driver’s station. This line provides control to both the coach’s rear brake relay valve and a small relay valve on the Demco reservoir. A final air line connects from the Demco reservoir relay valve to an air coupler at the rear of the coach for connection to the towed vehicle. This configuration is intended to isolate the towed vehicle’s braking system from the coach’s system, preventing adverse effects to the coach’s brakes in case of air line disconnection.
Installation and Components
The Air Force One operating unit is mounted under the hood of the towed vehicle, making it largely invisible. Installation involves connecting air lines to the coach’s air brake system and to the towed vehicle. The system is designed to tap into the chassis in a manner approved by some manufacturers, avoiding potential warranty issues associated with connecting to the rear wheels.
The system is supplied complete with all necessary components, including easy-to-follow instructions and a DVD. Users do not need to purchase additional parts for installation. Technical support is available 24/7 from SMI Manufacturing.
Coach Notification and Safety Features
A key feature of the Air Force One system is a notification system for the coach driver. This is accomplished through a high-density LED light mounted on the dash or mirror of the towed vehicle, visible to the coach driver via the back-up camera. The LED light illuminates whenever the brakes are applied in the towed vehicle, providing a clear visual indication of braking activity. This system relies on the towed vehicle’s brake light switch for activation.
The system also includes a patent-pending breakaway system designed to seal the coach’s air supply in the event of a separation between the coach and the towed vehicle. This feature is intended to enhance safety and prevent uncontrolled braking situations.
Compatibility and Considerations
The Air Force One system is specifically designed for coaches with air brakes and is stated to fit every tow vehicle, including newer vehicles with “live” pedal cars. It is compatible with diesel motorhomes.
It is important to note that some vehicles may draw power from the battery even when not in operation, potentially causing a battery drain. The documentation suggests consulting the towed vehicle’s owner’s manual to determine if a battery disconnect is recommended. Some vehicles may illuminate dashboard lights when the brakes are applied, or require the ignition to be in the auxiliary position during towing, both of which can contribute to battery drain.
Troubleshooting
One potential issue after installation is the towed vehicle’s brakes remaining applied after the parking brake/spring brake is released. This is likely caused by the metered airline connection being incorrectly tied into the parking brake/spring brake airline. The parking brake/spring brake is released with air, so if the Air Force One is connected to this line, it will receive a constant signal to apply the brakes. Correcting this requires verifying the correct metered airline connection.
Power Brake Activation and Battery Draw
The Air Force One system utilizes a patented process to create vacuum in the towed vehicle’s power brake system, energizing the power brakes without the engine running. This process does not require an electronic pump, eliminating the risk of battery drain associated with such pumps. The system is designed with no moving parts or circuit boards, further enhancing its reliability and reducing the potential for failure.
Alternative Braking Systems
Demco also offers other supplemental braking systems, including the Stay-in-Play brake system for RVs with hydraulic brakes and the Delta Force portable braking system. However, the Air Force One is specifically highlighted as meeting regulations and including all necessary components for installation, unlike some other systems that may require additional purchases.
Customer Feedback
Customer reviews indicate satisfaction with the system’s performance and ease of hookup. One user reported that the towed vehicle was virtually undetectable from the driver’s seat, requiring use of the rear-view camera to confirm the towed vehicle was still connected and the brake indicator was illuminated during braking.
Conclusion
The Demco Air Force One supplemental braking system offers a comprehensive solution for safely towing vehicles behind diesel motorhomes equipped with air brakes. Its proportional braking, hidden installation, and safety features, including the breakaway system and coach notification light, contribute to a secure and convenient towing experience. The system’s design, which avoids electronic pumps and moving parts, aims to provide long-term reliability and minimize maintenance. Proper installation and verification of air line connections are crucial for optimal performance.