Interpretation ID: nht89-1.61

TYPE: INTERPRETATION-NHTSA

DATE: 04/03/89

FROM: ERIKA Z. JONES -- CHIEF COUNSEL NHTSA

TO: DERREL T. CRANCE -- AUTOMOTIVE ENGINEER SALT RIVER PROJECT

TITLE: NONE

ATTACHMT: LETTER DATED 07/14/88 FROM DERRAL T. CRANCE TO ERIKA Z. JONES -- NHTSA, OCC 2310

TEXT: Dear Mr. Crance:

This responds to your letter requesting an interpretation of Federal Motor Vehicle Safety Standard No. 121, Air Brake Systems. I regret the delay in responding.

You stated that Salt River Project ordered 16 air-braked material/reel trailers and two air-braked transformer oil trailers. The trailers were built in 1987 and delivered by a vendor representing the manufacturer. You asked whether the trailers were re quired to conform to Standard No. 121 and, if so, whether a protected reservoir for parking brake release was required and whether the service reservoirs must be protected by check valves or the equivalent. In a telephone conversation with Edward Glancy of this office, you indicated that the trailers receive daily use on the public highways, and were intended for such use. Your questions are responded to below.

By way of background information, the National Highway Traffic Safety Administration does not provide approvals of motor vehicles. Under the National Traffic and Motor Vehicle Safety Act, it is the responsibility of the manufacturer to ensure that its v ehicles comply with applicable Federal motor vehicle safety standards. The following represents our opinion based on the facts provided in your letter and in the aforementioned telephone conversation.

Your first question was whether the trailers identified in your letter were subject to Standard No. 121. Section S3 of the standard provides that it applies to air-braked trailers, with certain exceptions. Thus, one issue raised by your letter is wheth er the trailers come within any of the exceptions. As discussed below, it is our opinion that the trailers do not come within any of the exceptions.

You indicated in the telephone conversation that the vendor and/or manufacturer suggested that the trailers come within the exception set forth in section S3(e). That section provides that the standard does not apply to "(a)ny trailer that has gross veh icle weight rating (GVWR) of more than 120,000 pounds and whose body conforms to that described in the definition of "Heavy hauler trailer" set forth in S4." (Emphasis added.) Thus, in order to come within the exception, a trailer must meet both of the c onditions set forth in that section, i.e., it must (1) have a GVWR of more than 120,000 pounds, and (2) have a body that conforms to the standard's definition of heavy hauler trailer. Since the GVWR's of the two types of trailers identified in your lett er are well below 120,000 pounds, the trailers do not come within that exception. Moreover, while it is not apparent why the vendor and/or manufacturer would believe that the trailers conform to the standard's definition of heavy hauler trailer. In add ition, based on our review of the other portions of section S3, the trailers do not appear to come within any of the other exceptions to Standard No. 121. Thus, it is our opinion that the trailers were subject to Standard No. 121.

Your second question was whether a protected reservoir for parking brake release was required by Standard No. 121. The answer to that question is yes. Section S5.2.1.1 provides the trailers must have a reservoir that "is capable, when pressurized to 90 p.s.i., of releasing the vehicle's parking brakes at least once and that is unaffected by a loss of air pressure in the service brake system."

Your third question was whether the service reservoirs must be protected by check valves or the equivalent. The answer to that question is also yes. Section S5.2.1.5 provides that each service reservoir for trailers must "be protected against loss of ai r pressure due to failure or leakage in the system between the service reservoir and its source of air pressure by check valves or equivalent devices."

Since your letter suggests that you purchased trailers that may not have complied with Standard No. 121, I have referred the matter to our Office of Vehicle Safety Compliance for appropriate action.

Sincerely,