Interpretation ID: nht75-3.43

DATE: 10/10/75

FROM: AUTHOR UNAVAILABLE; F. Berndt; NHTSA

TO: Truck Body and Equipment Association

TITLE: FMVSS INTERPRETATION

TEXT: This responds to your September 8, 1975, question whether trucks that carry specialized equipment (such as emergency medical equipment, fire fighting apparatus, or mobile power generator equipment), would qualify for exclusion from Standard No. 121, Air Brake Systems, if they are geared down or governed so that their speeds attainable in two miles are not more than 45 mph. You state that each vehicle's empty weight is more than 95 percent of its gross vehicle weight rating (GVWR).

The section of Standard No. 121 that lists the vehicles to which the standard applies reads as follows:

S3. Applicability. * * * In addition, the standard does not apply to any trailer whose unloaded vehicle weight is not less than 95 percent of its GVWR, or any vehicle that meets any one of criteria (a) through (d) as follows:

(d) (1) A speed attainable in two miles of not more than 45 mph; and

(2) An unloaded vehicle weight that is not less than 95 percent of the vehicle GVWR; and

(3) No passenger-carrying capacity.

From your description, it would appear that these vehicles would qualify for exclusion under category (d) of Section S3. The National Highway Traffic Safety Administration assumes that your description of emergency medical vehicles does not include an ambulance equipped with air brakes.

Sincerely,

TRUCK BODY AND EQUIPMENT ASSOCIATION, INC.

September 8, 1975

Richard Dyson, Assistant Chief Counsel National Highway Traffic Safety Administration

The recent amendment to FMVSS 121 relieving vehicles with an empty weight greater than 95% of the GVWR, no passenger or cargo carrying capacity and incapable of speeds in excess of 45 mph, from standard compliance has caused a number of questions from the truck body industry.

The questions center around a number of special duty vehicles designed and built to transport their self contained equipment rather than cargo. Examples of these vehicles would include: 1. Emergency communication vehicles

2. Emergency medical vehicles

3. Emergency electrical supply vehicles

4. Fire apparatus

Each of these vehicle types is generally completed on a commercial truck chassis with a piece or pieces of permanent equipment and its associated enclosures, i.e. large output generator sets, aerial ladder or elevating platform, mobile medical equipment. The chassis portion serves only as a means for transporting these pieces of equipment to the job site.

Where these vehicles are not designed or equipped to carry passengers or cargo, and their empty weight is always above 95% of the GVWR, are we correct in assuming that if the subject vehicles are physically restricted (governed, geared etc.) to speeds less than 45 mph then FMVSS 121 does not apply.

Byran A. Crampton Manager of Engineering Services