Interpretation ID: 17556.wkm

Mr. Enzo Bauk
Director of Engineering
Electric Vehicles International LLC
1331 Main Street
Anderson, IN 46016

Dear Mr. Bauk:

This responds to your letter of March 16, 1998 and refers to the telephone conversation of May 20, 1998 between Mr. O. L. Rand of your staff and Walter Myers of my staff. You stated that your company manufactures, among other things, electric buses and trolleys that use air-over-hydraulic (AOH) braking systems. You stated that there are currently no brake systems available that will permit you to comply with the antilock brake system (ABS) requirements of Federal Motor Vehicle Safety Standard (Standard) No. 121, Air brake systems. You enclosed a list of twenty-five manufacturers and suppliers whom you contacted but who could not or would not provide you the required equipment except at considerable additional cost because of the small number of units involved. You stated that you believe that the ABS requirement should not apply to your vehicles "until the market offers a reliable economically viable system for small equipment manufacturers."

Standard No. 121 defines air brake systems as follows:

Air brake system means a system that uses air as a medium for transmitting pressure or force from the driver control to the service brake, including an air-over-hydraulic brake subsystem, but does not include a system that uses compressed air or vacuum only to assist the driver in applying muscular force to hydraulic or mechanical components (emphasis added).

The standard further defines AOH brake systems as:

Air-over-hydraulic brake subsystem means a subsystem of the air brake system that uses compressed air to transmit a force from the driver control to a hydraulic brake system to actuate the service brakes.

Thus, the ABS requirements of Standard No. 121, by their terms, apply to your AOH-equipped vehicles.

In reviewing the list of companies that you contacted for AOH brake systems equipped with ABS, we noted that all those companies are U.S. manufacturers and suppliers. As Mr. Rand and Mr. Myers discussed in their telephone conversation, AOH systems are more commonly used in Europe and Japan than they are in the U.S. Thus, you could perhaps have better luck locating suppliers in those areas that could provide the components that you need. In that connection, I refer you to an article entitled Antilock Brakes, Part II which appears in the March 2, 1998 issue of Transport Topics, commencing at page 12. A brief discussion of the effect of antilock requirements on AOH systems appears at page 16 where the author comments on techniques used by Hino Diesel Trucks engineers in Japan (copy enclosed).

Mr. Rand and Mr. Myers also discussed the provisions of 49 Code of Federal Regulations, Part 555, TEMPORARY EXEMPTION FROM MOTOR VEHICLE SAFETY STANDARDS (copy enclosed). Mr. Taylor Vinson of this office ((202) 366-5263; fax (202) 366-3820) may be contacted for additional information on this procedure.

I hope this information is helpful to you. Should you have other questions or need additional information, feel free to contact Mr. Myers at this address or at (202) 366-2992, fax (202) 366-3820.

Sincerely,
Frank Seales, Jr.
Chief Counsel
Enclosures
d.7/9/98
ref:121