Interpretation ID: aiam2168
Divisional Manager
Quality Assurance
B. F. Goodrich Engineered Systems Company
500 South Main Street
Akron
OH 44318;
Dear Mr. Haines: This responds to your August 28, 1975, question whether use o compressed air from a trailer air brake system to supply non-brake equipment such as an air suspension would violate the requirements of Standard No. 121, *Air Brake Systems*.; The answer to your question is no. Standard No. 121 does not contain prohibition on the use of air pressure from the air brake system for powering auxiliary devices. The vehicle must of course conform to Standard No. 121 following installation of the device, if the installation occurs prior to the first purchase in good faith for purposes other than resale. For example, the brake actuation timing would still be required to meet S5.3.3 of the standard.; Although not a requirement of the standard, the NHTSA does consider i appropriate that a pressure protective valve be placed in the line to the auxiliary device so that a rupture of an auxiliary line does not cause depletion of air pressure in the brake system.; With respect to your request for approval of four installations o auxiliary equipment, the NHTSA does not issue approvals of specific designs, and therefore cannot state that vehicles modified in the described fashion would or would not be capable of meeting all requirements of the standard.; Yours truly, Richard B. Dyson, Assistant Chief Counsel