Federal Motor Carrier Safety Administration, DOT § 393.55

[36 FR 20298, Oct. 20, 1971, as amended at 37 the requirements of FMVSS No. 105 (49 FR 5251, Mar. 11, 1972; 37 FR 11336, June 7, CFR 571.105, S5.3). 1972; 68 FR 51777, Aug. 9, 2002] (c) Air brake systems. (1) Each truck tractor manufactured on or after § 393.53 Automatic brake adjusters and brake adjustment indicators. March 1, 1997 (except truck tractors engaged in driveaway-towaway oper- (a) Automatic brake adjusters (hydrau- ations), shall be equipped with an lic brake systems). Each commercial antilock brake system that meets the motor vehicle manufactured on or after requirements of FMVSS No. 121 (49 October 20, 1993, and equipped with a CFR 571.121, S5.1.6.1(b)). hydraulic brake system, shall meet the (2) Each air braked commercial automatic brake adjustment system motor vehicle other than a truck trac- requirements of Federal Motor Vehicle tor, manufactured on or after March 1, Safety Standard No. 105 (49 CFR 571.105, 1998 (except commercial motor vehicles S5.1) applicable to the vehicle at the engaged in driveaway-towaway oper- time it was manufactured. ations), shall be equipped with an (b) Automatic brake adjusters (air brake antilock brake system that meets the Each commercial motor vehi- systems). requirements of FMVSS No. 121 (49 cle manufactured on or after October CFR 571.121, S5.1.6.1(a) for trucks and 20, 1994, and equipped with an air brake buses, S5.2.3 for semitrailers, converter system shall meet the automatic brake dollies and full trailers). adjustment system requirements of (d) ABS malfunction circuits and sig- Federal Motor Vehicle Safety Standard nals for air braked vehicles. (1) Each No. 121 (49 CFR 571.121, S5.1.8) applica- truck tractor manufactured on or after ble to the vehicle at the time it was March 1, 1997, and each single-unit air manufactured. braked vehicle manufactured on or (c) Brake adjustment indicator (air after March 1, 1998, subject to the re- brake systems). On each commercial quirements of paragraph (c) of this sec- motor vehicle manufactured on or after tion, shall be equipped with an elec- October 20, 1994, and equipped with an trical circuit that is capable of sig- air brake system which contains an ex- naling a malfunction that affects the ternal automatic adjustment mecha- generation or transmission of response nism and an exposed pushrod, the con- or control signals to the vehicle’s dition of service brake under-adjust- antilock brake system (49 CFR 571.121, ment shall be displayed by a brake ad- S5.1.6.2(a)). justment indicator conforming to the (2) Each truck tractor manufactured requirements of Federal Motor Vehicle on or after March 1, 2001, and each sin- Safety Standard No. 121 (49 CFR 571.121, gle-unit vehicle that is equipped to tow S5.1.8) applicable to the vehicle at the another air-braked vehicle, subject to time it was manufactured. the requirements of paragraph (c) of [60 FR 46245, Sept. 6, 1995] this section, shall be equipped with an electrical circuit that is capable of § 393.55 Antilock brake systems. transmitting a malfunction signal from (a) Hydraulic brake systems. Each the antilock brake system(s) on the truck and bus manufactured on or after towed vehicle(s) to the trailer ABS March 1, 1999 (except trucks and buses malfunction lamp in the cab of the engaged in driveaway-towaway oper- towing vehicle, and shall have the ations), and equipped with a hydraulic means for connection of the electrical brake system, shall be equipped with circuit to the towed vehicle. The ABS an antilock brake system that meets malfunction circuit and signal shall the requirements of Federal Motor Ve- meet the requirements of FMVSS No. hicle Safety Standard (FMVSS) No. 105 121 (49 CFR 571.121, S5.1.6.2(b)). (49 CFR 571.105, S5.5). (3) Each semitrailer, trailer con- (b) ABS malfunction indicators for hy- verter dolly, and full trailer manufac- draulic braked vehicles. Each hydraulic tured on or after March 1, 2001, and braked vehicle subject to the require- subject to the requirements of para- ments of paragraph (a) of this section graph (c)(2) of this section, shall be shall be equipped with an ABS mal- equipped with an electrical circuit that function indicator system that meets is capable of signaling a malfunction in

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the trailer’s antilock brake system, mm (1 inch) border at each side of the and shall have the means for connec- windshield or windshield panel. Excep- tion of this ABS malfunction circuit to tions: the towing vehicle. In addition, each (1) Coloring or tinting which meets trailer manufactured on or after March the requirements of paragraph (d) of 1, 2001, subject to the requirements of this section; paragraph (c)(2) of this section, that is (2) Any crack that is not intersected designed to tow another air-brake by any other cracks; equipped trailer shall be capable of (3) Any damaged area which can be transmitting a malfunction signal from covered by a disc 19 mm (3⁄4 inch) in di- the antilock brake system(s) of the ameter if not closer than 76 mm (3 trailer(s) it tows to the vehicle in front inches) to any other similarly damaged of the trailer. The ABS malfunction area. circuit and signal shall meet the re- (d) Coloring or tinting of windshields quirements of FMVSS No. 121 (49 CFR and windows. Coloring or tinting of 571.121, S5.2.3.2). windshields and the windows to the im- (e) Exterior ABS malfunction indicator mediate right and left of the driver is lamps for trailers. Each trailer (includ- allowed, provided the parallel luminous ing a trailer converter dolly) manufac- transmittance through the colored or tured on or after March 1, 1998 and be- tinted glazing is not less than 70 per- fore March 1, 2009, and subject to the cent of the light at normal incidence in requirements of paragraph (c)(2) of this those portions of the windshield or section, shall be equipped with an ABS windows which are marked as having a malfunction indicator lamp which parallel luminous transmittance of not meets the requirements of FMVSS No. less than 70 percent. The transmittance 121 (49 CFR 571.121, S5.2.3.3). restriction does not apply to other windows on the commercial motor vehicle. [63 FR 24465, May 4, 1998] (e) Prohibition on obstructions to the driver’s field of view—(1) Devices mounted Subpart D—Glazing and Window at the top of the windshield. Antennas, Construction transponders, and similar devices must not be mounted more than 152 mm (6 § 393.60 Glazing in specified openings. inches) below the upper edge of the (a) Glazing material. Glazing material windshield. These devices must be lo- used in windshields, windows, and cated outside the area swept by the doors on a motor vehicle manufactured windshield wipers, and outside the on or after December 25, 1968, shall at a driver’s sight lines to the road and minimum meet the requirements of highway signs and signals. Federal Motor Vehicle Safety Standard (2) Decals and stickers mounted on the (FMVSS) No. 205 in effect on the date windshield. Commercial Vehicle Safety of manufacture of the motor vehicle. Alliance (CVSA) inspection decals, and The glazing material shall be marked stickers and/or decals required under in accordance with FMVSS No. 205 (49 Federal or State laws may be placed at CFR 571.205, S6). the bottom or sides of the windshield (b) Windshields required. Each bus, provided such decals or stickers do not 1 truck and truck-tractor shall be extend more than 115 mm (4 ⁄2 inches) equipped with a windshield. Each wind- from the bottom of the windshield and shield or portion of a multi-piece wind- are located outside the area swept by shield shall be mounted using the full the windshield wipers, and outside the periphery of the glazing material. driver’s sight lines to the road and (c) Windshield condition. With the ex- highway signs or signals. ception of the conditions listed in para- [63 FR 1387, Jan. 9, 1998] graphs (c)(1), (c)(2), and (c)(3) of this section, each windshield shall be free of § 393.61 Truck and truck tractor win- discoloration or damage in the area ex- dow construction. tending upward from the height of the Each truck and truck tractor (except top of the steering wheel (excluding a trucks engaged in armored car service) 51 mm (2 inch) border at the top of the shall have at least one window on each windshield) and extending from a 25 side of the driver’s compartment. Each

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