Interpretation ID: aiam0923
Manager
Vehicle Legislation
Whitley Technical Centre
Chrysler United Kingdom Ltd.
Coventry CV3 4CB
England;
Dear Mr. Morris:#This is in reply to your letter of November 7, 1972 about Federal Motor Vehicle Safety Standard No. 102 as applied to a four speed automatic gear box.#As described, your transmission functions as follows:#>>>'When the gear selector is in any forward position and the vehicle speed falls the automatic mechanism will cause the drive ratio to eventually fall to the lowest gear and thereafter to disengage at about 6 mph leaving the vehicle in a state of 'free-wheel'.'<<<#Paragraph S3.1.2, Transmission Braking Effect, requires that:#>>>'In vehicles having more than one forward transmission gear ratio, one forward drive position shall provide a greater degree of engine braking than the highest speed transmission ratio at vehicle speeds below 25 miles per hour.'<<<#Your transmission, as described, does not meet this requirement, since, in downshifting, the drive ratio would disengage at about 6 miles per hour leaving the vehicle in a state of 'free-wheel' with no engine braking at all.#Sincerely, E. T. Driver, Director, Office of Operating Systems, Motor Vehicle Programs;