Interpretation ID: 86-1.22

TYPE: INTERPRETATION-NHTSA

DATE: 02/06/86

FROM: AUTHOR UNAVAILABLE; Erika Z. Jones; NHTSA

TO: Mr. Robert J. Crail

TITLE: FMVSS INTERPRETATION

TEXT:

February 6, 1986 Mr. Robert J. Crail Theurer, Inc. Route 1, Box 300 Helenwood, Tennessee 37755 Dear Mr. Crail: This responds to your letter of August 20, 1985, requesting an interpretation of Standard No. 121, Air Brake Systems (49 CFR 571.121). You asked whether an extendible intermodel container chassis which adjusts to haul containers which vary in length between 40 feet and 48 feet is a "heavy hauler trailer" as defined in Section S4 of Standard No. 121. Specifically, you would like to know whether the extendible container chassis described above must comply with Sections S5.2.1.2 and S5.3, and whether you or your customer may utilize the options available in Section S5.6 for parking brake systems and in Section S5.8 for emergency brake systems. By way of background information, this agency does not give approvals of motor vehicles or equipment. The National Traffic and Motor Vehicle Safety Act places the responsibility on the manufacturer to ensure that its vehicles or equipment comply with applicable requirements. A manufacturer then certifies that its vehicles or equipment comply with applicable requirements. The following represents our opinion based on the facts provided in your letter. The extendible container chassis trailers which you describe have brake lines which are designed to extend with the vehicle frame. According to Section S4 of Standard No. 121, a trailer whose "brake lines are designed to adapt to separation or extension of the vehicle frame...." is, by definition, a heavy hauler trailer. Thus, your extendible chassis trailer would be considered a heavy hauler trailer within the definition of S4. Section S5.2.1.2 of Standard No. 121 provides that trailers with air brakes are generally required to have total service reservoir volume which is "at least eight time the combined volume of all service brake chambers at maximum travel of the pistons or diaphragms." This general rule is limited by the last sentence of S5.2.1.2 which provides, "However, the reservoir on a heavy hauler trailer ... need not meet this requirement." Section S5.3 sets forth road test requirements, compliance with which must be certified for all trucks, buses and trailers. Generally, all trailers are required to be certified as complying with the timing requirements of S5.3.3 and S5.3.4. This general rule is limited by the last sentence of S5.3, which specifies, "However, a heavy hauler trailer ... need not meet the requirements of S5.3." Thus, heavy hauler trailers are expressly excepted from all of the requirements of S5.3. Finally, you asked whether the trailer you manufacture may take advantage of the options available in Section S5.6 for the parking brake system and in Section S5.8 for the emergency brake system. Both Sections S5.6 and S5.8 specifically give manufacturers of heavy hauler trailers the choice of complying with the requirements of those sections... "or at the option of the manufacturer, the requirements of sec. 393.43 of this title." Title 49 CFR section 393.43 sets forth requirements for breakaway and emergency brakes. An extendible container chassis which comes within the S4 definition of heavy hauler trailer may comply with the section 393.43 requirements or the parking emergency brake requirements or the parking and emergency brake requirements of Standard No. 121 Sections S5.6 and S5.8, respectively. If you have any further questions, please let me know. Sincerely, Original Signed By Erika Z. Jones Chief Counsel