When a motorhome flat-tows a car, the towed vehicle is not simply cargo: it has wheels and a braking system that need to work as intended. A supplemental brake can help share stopping work between coach and towed car, but choosing it is not as simple as shopping by “best brand.” Your coach’s braking architecture, the specific car, its flat-towing approval and the breakaway arrangement all affect the answer. Get those pieces wrong and even a premium product can become an expensive safety problem.
Side-by-side comparison
Start with these product and compatibility distinctions, then inspect the shortlisted models and the decision factors below. Check the exact SKU before buying: model variants and bundles change.
| System | Coach use case | Install style | Check before purchase |
|---|---|---|---|
| Demco Air Force One | Air-brake motorhome | Permanent air-integrated | Coach air kit, chassis approvals and professional installation |
| Demco Stay-IN-Play DUO | Hydraulic-brake motorhome | Permanent progressive braking | Coach/towed vehicle electrical and pedal compatibility |
| Blue Ox Patriot / Brake Buddy class | Owners preferring portable equipment | Floor-mounted actuator in towed vehicle | Specific current model, battery setup and adjustment instructions |
| ReadyBrake-type mechanical systems | Compatible mechanical tow-bar setup | Cable-actuated | Tow-bar model, breakaway system and installation routing |
Products and systems worth comparing
These are specification-based editorial comparisons, not claims that RVGear purchased or personally tested each model. Always verify current manufacturer documentation, seller listings and vehicle-specific limits. Marketplace buttons use the RVGear eBay affiliate campaign already present in the site's existing links. Listings are searches, not claimed direct product matches.
Demco Air Force One
Air Force One integrates with supported coach air-brake arrangements to provide supplemental braking in the towed car. It is a permanent installation designed for owners who regularly tow the same vehicle. That convenience can be appealing, but it makes proper coach-side and vehicle-side installation central to the buying decision.
Permanent integration and an approach intended for air-brake coaches.
Air source approval, chassis-specific components, baseplate/towbar wiring and qualified installation.
Demco Stay-IN-Play DUO
Stay-IN-Play DUO uses a different system architecture for supported motorhomes without the air-brake arrangement Air Force One expects. Installation can be discreet once completed, which appeals to people who do not want to place a box on the driver’s floor every travel day.
Permanent setup for supported hydraulic-brake motorhomes.
Electrical setup, specific towed-car pedal behavior, breakaway details and current manual.
Portable pedal-actuating systems
Portable systems such as current Brake Buddy or Blue Ox Patriot-family products are positioned inside the towed car and actuate the brake pedal when properly installed. The main trade-off is repeatable setup. They may fit travelers who occasionally swap towed vehicles but do not want a permanent unit installed in each one.
Can be removed and transferred between eligible vehicles.
Current model compatibility, seat/footwell space, pedal calibration, power requirements and installation procedure.
ReadyBrake-style mechanical braking
Some mechanical systems use towbar motion and a cable arrangement rather than relying on the same electronics as portable and air-operated systems. Their simplicity can be attractive, but cable routing, steering movement and breakaway operation are not optional installation details.
Potentially simple operating concept when the entire towing system is compatible.
Exact towbar, car routing, safety cable and breakaway specifications.
First, verify the towed car is approved for flat towing
No braking system makes an otherwise incompatible car safe to tow with all four wheels on the ground. Owners’ manuals often distinguish between drivetrains, transmission types, model years and specific procedures for shifting into a tow mode. Some require special fuses, battery charging or steering and key-position procedures. Use the manufacturer’s instructions for the exact year and configuration, not a generic online list for that model name.
The motorhome’s tow rating, hitch receiver, towbar, baseplate, safety cables and auxiliary brake must also work as a single approved system. Always obey the lowest relevant rating. Consider the added weight of accessories and cargo inside the towed vehicle, not just its empty curb weight.
Air-brake coach versus hydraulic-brake coach
This is the fastest way to narrow the shortlist. Many diesel-pusher motorhomes have air brakes; many gasoline chassis use hydraulic service brakes. Those general patterns do not replace checking your chassis. Air Force One is built around an approved air-based signal and its installation kit. Stay-IN-Play DUO uses a different arrangement better suited to supported hydraulic-brake coaches. A product advertisement that says “universal” should not take precedence over the installation manual.
Why some owners prefer portable braking
Portable units avoid some permanent car-side hardware and may be more adaptable when changing tow vehicles. They also impose a pre-departure routine. You must place the unit correctly, attach the pedal mechanism, connect its power, perform setup/calibration as directed and verify functionality every time. If your travel is frequent and you keep one car for years, a permanent system may reduce daily work even when its installed price is higher.
A breakaway system is not an optional afterthought
The breakaway arrangement is intended to actuate the towed vehicle brakes if it detaches. Cables and switches have exact mounting and routing requirements. Do not attach a breakaway cable in a way that allows it to snag, disconnect with the towbar or operate incorrectly during a tight turn. Follow the manufacturer's test method, including battery support where required.
Checking the taillights or brake lights is useful for lighting setup, but it does not prove the towed vehicle’s brakes are physically applying. You need the specified functional check for your braking product.
Pre-trip flat-tow inspection
- Confirm towability and the required tow mode for the exact car and drivetrain.
- Check coach, hitch, towbar and baseplate ratings, fasteners and safety cable routing.
- Connect and inspect the brake system, its power supply and communication components as instructed.
- Test the breakaway system and braking function using the manufacturer's procedure.
- Verify all travel-route requirements; braking thresholds vary by state and jurisdiction.
Frequently asked questions
Can I use Air Force One with a hydraulic-brake motorhome?
Demco markets Air Force One for supported air-brake coaches. Do not assume it fits a hydraulic-brake motorhome; compare an appropriate hydraulic-compatible system.
Does a brake light test prove the supplemental system works?
No. Lighting and mechanical brake actuation are separate. Use the manufacturer’s actual braking and breakaway test procedure.
Are supplemental brakes required in every state?
Rules differ. The applicability may depend on weight thresholds, vehicle classes and other details along your route.
Can I move a portable brake system between cars?
Sometimes, if the specific model and each vehicle are approved and you repeat correct installation and calibration each time.
Will a supplemental brake make any car safe to flat tow?
No. The car itself must be approved for flat towing and prepared according to its own manual.
Read these related RV guides
Sources and editorial approach
This guide uses publicly documented manufacturer information, with important qualifications noted next to affected claims. Product configurations change; check actual manufacturer instructions and current listings before purchase. We do not imply personal testing, verified merchant availability, or guaranteed pricing.
- https://www.demco-products.com/rv-towing/supplemental-brakes
- https://www.demco-products.com/supplemental-braking-system-manuals
- https://www.blueox.com/
- https://www.readybrake.com/
Affiliate disclosure: RVGear may earn a commission from qualifying marketplace purchases. Affiliate relationships do not establish product performance or fit.