Interpretation ID: aiam2693

Mr. John W. Kourik, Chief Engineer, Wagner Electric Corporation, 11444 Lackland Road, St. Louis, MO 63141; Mr. John W. Kourik
Chief Engineer
Wagner Electric Corporation
11444 Lackland Road
St. Louis
MO 63141;

Dear Mr. Kourik: This responds to Wagner Electric Corporation's October 26, 1977 request for confirmation that S5.6.4 of Standard No. 121, *Air Brake Systems*, does not prohibit the use of a two-valve sequential means to release the parking brakes on a towed vehicle.; I have enclosed for your information an interpretation that addresse this question, stating that a two-valve sequential release is permissible under S5.6.4.; Sincerely, Joseph J. Levin, Jr., Chief Counsel