Slowing and stopping a towed vehicle can be tricky. To simplify this, SMI Brake, Newburg, Ind., turned to Clippard Instrument Laboratory, Cincinnati, and Isaacs Fluid Power, Indianapolis, to provide solutions for braking a towed vehicle. Pneumatics was chosen over solenoids because of its compact size, efficiency, consistency and long term reliability.
SMI offers three solutions that enable the safe braking of a vehicle being towed by a motor home—Air Force One, Stay-In-Play Duo and Delta Force. All three systems are not only safe and reliable, but according to SMI, they are economical and offer the best warranty in the business.
Air Force One operates by using a small amount of air from the motor home’s air supply to create the necessary vacuum for operating the towed vehicle’s power brake system and drive the brake actuator. True proportionate braking is achieved as a result of the direct connection. This supplemental system is also touted as one that provides true coach protection with a patent-pending breakaway system that seals the coach’s air supply in the event of a separation. According to SMI, this protection kit is the only DOT-compliant and chassis-approved air-based system.
Clippard manufactures the actuator that is mounted directly to the braking arm but above the brake pedal. Clippard’s Value Added team, along with its design engineers, created this special stainless steel actuator, mounting brackets and the necessary hardware in order to meet SMI’s stringent quality standards. And, according to Brent Schuck, general manager at SMI, knowing Clippard’s standard for high quality was one of the determining factors in selecting them as a partner.
“We moved to Clippard from another national manufacturer because of Clippard’s attitude toward the customer,” Schuck said. “Tooling, material and processes change and over time will create inconsistency. When these minute variances combine to cause an issue, Clippard moves quickly and with great concern, as opposed to the other brand that would treat us like it was our fault.”
The Stay-In-Play Duo system uses both air pressure and vacuum. Vacuum is used to operate the towed vehicle’s power brakes and air pressure to apply the brakes. Duo’s small operating unit is located under the hood and provides a streamlined approach to the braking operation. As with the Air Force One system, Clippard manufactures the SS-1119-10 stainless steel actuator, mounting brackets and hardware. According to Schuck, these actuators have been used thousands of times without any problems. Here again is the correlation between quality products and safety. Duo requires deceleration and brake lights from the coach in order for the brakes on the towed vehicle to be applied. The approach of combining two separate signals, according to SMI, eliminates the need for complicated electronics.
The newest control system offered by SMI is called Delta Force. Unlike the Air Force One and Stay-In-Play systems, which have their control unit mounted under the hood, the Delta Force control is portable and positioned on the floor of the towed vehicle. Although portable units have not been popular for a number of years, Schuck said SMI got into the market simply because of demand from existing customers and its reputation for manufacturing a quality product. Because of the partnership with Clippard and Isaccs on the other units, Schuck said that is what made for a smooth partnership on the new system.
“Custom solutions like these from Clippard allow us the freedom to design without the limitation of shelf-only parts,” Schuck said. “They also offer great insight and assistance when designing pneumatic circuits.”
Delta Force’s control unit is positioned on the towed vehicle’s floor in front of the brake pedal. The unit houses its own compressor, therefore eliminating the need for an air supply from an external source. Housed inside the unit are two Clippard EV series electronic valves mounted on a special manifold with fittings. This value-added unit functions as a fill-and-bleed operation, a normally open circuit that requires the solenoid to be tripped in order to hold in the air as part of the safety system.
Attached to the control unit is Clippard’s SS-1283-1 stainless steel actuator designed specifically for this application. One end of the actuator has a ball and socket that is attached to the front of the Delta unit. The other end uses a Clippard clevis bracket and it is attached to SMI’s patent-pending pedal clamp. The tether is secured to the firewall and to the back of the cylinder by the tether bracket and carabiner clip.
According to Schuck, customers love the simplicity, quality and ease of installation of the new system. He also noted that a great portion of the success of the program has been the willingness of SMI, Isaacs and Clippard in working together to make a safe product.
Clippard Instrument Laboratory