§ 393.41 49 CFR Ch. III (10–1–11 Edition)

(4) Electric systems. Motor vehi- be located so that the driver can oper- cles equipped with electric brake sys- ate it from the normal seating position tems must have a service brake system while restrained by any seat belts with that meets the applicable requirements which the vehicle is equipped. The of §§ 393.42, 393.48, 393.49 and 393.52 of emergency brake control may be com- this subpart. bined with either the service brake (5) Surge brake systems. Motor vehicles control or the control. equipped with surge brake systems However, all three controls may not be must have a service brake system that combined. meets the applicable requirements of (f) Interconnected systems. (1) If the §§ 393.42, 393.48, 393.49, and 393.52 of this brake systems required by § 393.40(a) subpart. are interconnected in any way, they (c) Parking . Each commercial must be designed, constructed, and motor vehicle must be equipped with a maintained so that in the event of a parking brake system that meets the failure of any part of the operating applicable requirements of § 393.41. mechanism of one or more of the sys- (d) Emergency brakes—partial failure of tems (except the service brake actu- service brakes—(1) sys- ation pedal or valve), the motor vehicle tems. Motor vehicles manufactured on will have operative brakes and, for ve- or after September 2, 1983, and hicles manufactured on or after July 1, equipped with a split service brake sys- 1973, be capable of meeting the require- tem must, at a minimum, meet the ments of § 393.52(b). partial failure requirements of FMVSS (2) A motor vehicle to which the re- No. 105 in effect on the date of manu- quirements of FMVSS No. 105 (S5.1.2), facture. dealing with partial failure of the serv- (2) systems. Buses, trucks ice brake, applied at the time of manu- and truck tractors manufactured on or facture meets the requirements of after March 1, 1975, and trailers manu- § 393.40(f)(1) if the motor vehicle is factured on or after January 1, 1975, maintained in conformity with FMVSS must be equipped with an emergency No. 105 and the motor vehicle is capa- brake system which, at a minumum, ble of meeting the requirements of meets the requirements of FMVSS No. § 393.52(b), except in the case of a struc- 121 in effect on the date of manufac- tural failure of the brake master cyl- ture. inder body. (3) Vehicles not subject to FMVSS Nos. (3) A bus is considered to meet the re- 105 and 121 on the date of manufacture. quirements of § 393.40(f)(1) if it meets Buses, trucks and truck tractors not the requirements of § 393.44 and subject to FMVSS Nos. 105 or 121 on § 393.52(b). the date of manufacture must meet the requirements of § 393.40(e). Trailers not [70 FR 48048, Aug. 15, 2005, as amended at 72 subject to FMVSS No. 121 at the time FR 9870, Mar. 6, 2007] of manufacture must meet the require- ments of § 393.43. § 393.41 Parking brake system. (e) Emergency brakes, vehicles manu- (a) Hydraulic-braked vehicles manufac- factured on or after July 1, 1973. (1) A tured on or after September 2, 1983. Each bus, truck, truck tractor, or a com- truck and bus (other than a school bus) bination of motor vehicles manufac- with a GVWR of 4,536 kg (10,000 pounds) tured on or after July 1, 1973, and not or less which is subject to this part and covered under paragraphs (d)(1) or school buses with a GVWR greater than (d)(2) of this section, must have an 4,536 kg (10,000 pounds) shall be emergency brake system which con- equipped with a parking brake system sists of emergency features of the serv- as required by FMVSS No. 571.105 (S5.2) ice brake system or an emergency sys- in effect at the time of manufacture. tem separate from the service brake The parking brake shall be capable of system. The emergency brake system holding the vehicle or combination of must meet the applicable requirements vehicles stationary under any condi- of §§ 393.43 and 393.52. tion of loading in which it is found on (2) A control by which the driver ap- a public road (free of ice and snow). Hy- plies the emergency brake system must draulic-braked vehicles which were not

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subject to the parking brake require- leased unless adequate energy is avail- ments of FMVSS No. 571.105 (S5.2) must able to immediately reapply the park- be equipped with a parking brake sys- ing brake with the required effective- tem that meets the requirements of ness. paragraph (c) of this section. (b) Air-braked power units manufac- [70 FR 48048, Aug. 15, 2005] tured on or after March 1, 1975, and air- § 393.42 Brakes required on all wheels. braked trailers manufactured on or after January 1, 1975. Each air-braked bus, (a) Every commercial motor vehicle truck and truck tractor manufactured shall be equipped with brakes acting on on and after March 1, 1975, and each all wheels. air-braked trailer except an agricul- (b) Exception. (1) Trucks or truck tural commodity trailer, converter tractors having three or more axles dolly, heavy hauler trailer or pulpwood and manufactured before July 25, 1980, trailer, shall be equipped with a park- are not required to have brakes on the ing brake system as required by front wheels. However, these vehicles FMVSS No. 121 (S5.6) in effect at the must meet the requirements of § 393.52. time of manufacture. The parking (2) Motor vehicles being towed in a brake shall be capable of holding the driveaway-towaway operation are not vehicle or combination of vehicles sta- required to have operative brakes pro- tionary under any condition of loading vided the combination of vehicles in which it is found on a public road meets the requirements of § 393.52. This (free of ice and snow). An agricultural exception is not applicable to: commodity trailer, heavy hauler or (i) Any motor vehicle towed by pulpwood trailer shall carry sufficient means of a tow-bar when another chocking blocks to prevent movement motor vehicle is full-mounted on the when parked. towed vehicle; and (c) Vehicles not subject to FMVSS Nos. (ii) Any combination of motor vehi- 105 and 121 on the date of manufacture. cles utilizing three or more saddle- (1) Each singly driven motor vehicle mounts. not subject to parking brake require- (3) Any semitrailer or pole trailer ments of FMVSS Nos. 105 or 121 at the (laden or unladen) with a gross weight time of manufacturer, and every com- of 1,361 kg (3,000 pounds) or less which bination of motor vehicles must be is subject to this part is not required to equipped with a parking brake system be equipped with brakes if the axle adequate to hold the vehicle or com- weight of the towed vehicle does not bination on any grade on which it is exceed 40 percent of the sum of the axle operated, under any condition of load- weights of the towing vehicle. ing in which it is found on a public (4) Any full trailer or four-wheel pole road (free of ice and snow). trailer (laden or unladen) with a gross (2) The parking brake system shall, weight of 1,361 kg (3,000 pounds) or less at all times, be capable of being applied which is subject to this part is not re- by either the driver’s muscular effort quired to be equipped with brakes if or by spring action. If other energy is the sum of the axle weights of the used to apply the parking brake, there towed vehicle does not exceed 40 per- must be an accumulation of that en- cent of the sum of the axle weights of ergy isolated from any common source the towing vehicle. and used exclusively for the operation (5) Brakes are not required on the of the parking brake. steering axle of a three-axle dolly Exception: This paragraph shall not be which is steered by a co-driver. applicable to air-applied, mechani- (6) Loaded housemoving dollies, spe- cally-held parking brake systems cialized trailers and dollies used to which meet the parking brake require- transport industrial furnaces, reactors, ments of FMVSS No. 121 (S5.6). and similar motor vehicles are not re- (3) The parking brake system shall be quired to be equipped with brakes, pro- held in the applied position by energy vided the speed at which the combina- other than fluid pressure, air pressure, tion of vehicles will be operated does or electric energy. The parking brake not exceed 32 km/hour (20 mph) and system shall not be capable of being re- brakes on the combination of vehicles

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