Interpretation ID: aiam3564
President
Transquip Industries
Inc.
1222 RepublicBank Oak Cliff
Dallas
TX 75208;
Dear Mr. Clapp: This responds to your recent letter asking whether Federal regulation allow a brake hose to be used as a dual purpose hose for both the service brakes and the emergency brake.; Standard No. 121, *Air Brake Systems*, does not preclude the use o common components in parking, emergency, and service air brake systems. Accordingly, nothing would prevent you from using a common hose in those systems. However, the common component would have to comply with the requirements for each system. This means that a failure of the hose would always be treated as a failure in the parking, emergency and service brake systems. Applying this to the standard in section S5.2.1.1, it would be necessary for the parking brakes to be capable of being released with a failure of the common hose at any time. If your system cannot perform in this manner, which it appears it cannot, it could not comply with the safety standard.; Our engineering staff has reviewed your brake system very carefull over the past years. It appears that your system can be properly plumbed in a manner that it would seem to comply with the requirements. You have continued to seek slightly less expensive methods to plumb your system. In our opinion, these methods would not be capable of complying with the standard. We cannot see how your system can comply with the standard without traditional plumbing that is being used by many brake manufacturers today. Accordingly, we suggest that you concentrate your efforts on constructing your system in that manner.; Sincerely, Frank Berndt, Chief Counsel