Interpretation ID: aiam2383

Mr. Richard J. Brandewie, Program Manager, B.F. Goodrich Engineered Systems Company, P.O. Box 340, Troy, OH 45373; Mr. Richard J. Brandewie
Program Manager
B.F. Goodrich Engineered Systems Company
P.O. Box 340
Troy
OH 45373;

Dear Mr. Brandewie: This responds to your July 26, 1976, question whether the 'no lockup requirement of S5.3.1 and S5.3.2 of Standard No. 121, *Air Brake Systems*, requires wheel sensors on both axles of a tandem axle system in those cases where the 'no lockup' performance is provided by means of an antilock system. I have enclosed a detailed discussion of this issue that responded to a similar question from another manufacturer. The response should answer your question.; Yours truly, Frank Berndt, Acting Chief Counsel