Bus Chassis Standards

(1) Air Cleaner. (a) The engine intake air cleaner system shall be furnished and properly installed by the chassis manufacturer to meet engine manufacturer's specifications. (b) The intake air system for diesel engines may have an air cleaner restriction indicator properly installed by the chassis manufacturer to meet engine specifications. (2) Axles. The front and rear ends, including suspension assemblies, shall have a gross axle weight rating, at ground, at least equal to that portion of the load as would be imposed by the chassis manufacturer's maximum gross vehicle weight rating. (3) Brakes. A braking system, including service brake and parking brake, that meets the following standards shall be provided. (a) Buses using air or vacuum in the operation of the brake system shall be equipped with warning signals, readily audible and visible to the driver, that will give a continuous warning when the air pressure available in the system for braking is 60 psi (pounds per square inch) or less or the vacuum in the system available for braking is eight inches of mercury or less. An illuminated gauge that will indicate to the driver the air pressure in pounds per square inch or the inches of mercury vacuum available for the operation of the brakes shall be provided. (b) Vacuum-assist brake systems shall have a reservoir used exclusively for brakes that shall be adequate to ensure loss in vacuum at full stroke applicable of not more than 30% with the engine not running. Brake systems on gas-powered engines shall include suitable and convenient connection for the installation of a separate vacuum reservoir. (c) Any brake system dry reservoir shall be so safeguarded by a check valve or equivalent device that, in the event of failure or leakage in its connection to the source of compressed air or vacuum, the stored dry air or vacuum shall not be depleted by the leakage or failure. (d) Buses using a hydraulic-assist brake system shall be equipped with warning signals, readily audible and visible to the driver, that will provide continuous warning in the event of a loss of fluid flow from primary source or loss of electric source powering the back-up system. (e) The brake lines and the hydraulic-assist lines shall be protected from excessive heat and vibration and be so installed as to prevent chafing. (f) All brake systems shall be designed to permit visual inspection of brake lining wear without removal of any chassis components. (4) Front Bumper. (a) School buses shall be equipped with a front bumper. The front bumper shall be furnished by the chassis manufacturer for all school bus types unless there is a specific agreement between the chassis manufacturer and the body manufacturer. (b) The front bumper shall be of pressed steel channel or equivalent material (except Type A buses having a GVWR of 12,500 lbs. or less which may be OEM supplied) at least 16 / inch thick and not less than eight inches wide (high). It shall extend beyond the forward- 3 most part of the body, grille, hood, and fenders and shall extend to the outer edges of the fenders at the bumper's top line. (c) The front bumper, except breakaway bumper ends, shall be of sufficient strength to permit pushing a vehicle of equal gross vehicle weight (GVW) without permanent distortion to the bumper, chassis, or body. (d) Tow eyes or hooks may be furnished. Tow eyes or hooks if provided, shall be attached so as not to project beyond the front bumper. Tow eyes or hooks attached to the frame chassis shall be furnished by the chassis manufacturer. This installation shall be in accordance with the chassis manufacturer's standards. (e) The bumper shall be designed or reinforced so that it will not deform when the bus is lifted by a chain that is passed under the bumper (or through the bumper if holes are provided for this purpose) and attached to both tow eyes. For the purpose of meeting this specification, the bus shall be empty and positioned on a level, hard surface and both tow eyes shall share the load equally. (f) An energy absorbing front bumper may be used providing its design shall incorporate a self-restoring energy absorbing system of sufficient strength to: 1. push another vehicle of similar GVW without permanent distortion to the bumper, chassis, or body; and 2. withstand repeated impacts without damage to the bumper, chassis, or body according to the following FMVSS performance standards: a. 7.5 MPH fixed barrier impact (FMVSS cart and barrier test); b. 4.0 MPH corner impact at 30° (49 CFR 581). 3. The manufacturer of the energy absorbing system shall provide evidence from an approved test facility (capable of performing the above FMVSS tests) that its product conforms to the above standard. (5) Rear Bumper. The rear bumper shall be made of pressed steel channel or equivalent 16 material at least / inch thick and eight inches wide (high), and of sufficient strength to permit 3 pushing by another vehicle without permanent distortion. (a) The bumper shall be wrapped around the back corners of the bus, and shall extend forward at least 12 inches, measured from the rear-most point of the body at the floor line; (b) The bumper shall be attached to the chassis frame as to be easily removed, and to discourage the hitching of rides, and shall be braced to develop the full strength of the bumper section from rear or side impact; (c) The bumper shall extend at least one inch beyond the rear-most part of body surface measured at the floor line; (d) The bumper provided by the chassis manufacturer may be used on Type A vehicles; (e) An energy-absorbing rear bumper may be used, providing its design shall incorporate a self-restoring energy absorbing bumper system of sufficient strength to: 1. permit pushing by another vehicle without permanent distortion to the bumper, chassis, or body; 2. withstand repeated impacts without damage to the bumper, chassis, or body according to the following FMVSS performance standards; a. 2.0 MPH fixed barrier impact (FMVSS cart and barrier test) b. 4.0 MPH corner impact at 30° (49 CFR 581) c. 5.0 MPH center impact (49 CFR 581) 3. The manufacturer of the energy-absorbing system shall provide evidence from an approved test facility (capable of performing the above FMVSS test) that its product conforms to the above standard. (6) Certification. Upon request, a chassis manufacturer will certify to the Registrar that its product meets Massachusetts minimum standards on items not covered by certification issued under the National Traffic and Motor Vehicle Safety Act. (7) Drive Shaft. The drive shaft shall be protected by a metal guard or guards around each section to reduce the possibility of it whipping through the floor or dropping to the ground if broken. (8) Exhaust System. The exhaust system, including the exhaust manifold, gaskets, pipes and mufflers, shall be secure, tight and free from exhaust leaks. The exhaust pipe will exit flush with bumper and left side will exit flush with outside of the bus body. (a) The exhaust pipe, muffler and tailpipe shall be outside the bus body compartment and attached to the chassis. (b) The tailpipe shall be constructed of a corrosion-resistant tubing material at least equal in strength and durability to 16-gauge steel tubing and shall extend to, but not beyond, the perimeter of the body or bumper. (c) The tailpipe shall extend beyond the rear axle and at least five inches beyond the chassis frame. It may be mounted outside of the chassis frame rail at end point, or may extend to the left side of the bus, behind the driver's compartment, outboard of the chassis centerline. It shall terminate from the chassis centerline as follows: Type A vehicles - Manufacturer's standard Type B, C, and D vehicles - 48.5 inches (d) On Type C and D buses, no exhaust pipe shall exit beneath an emergency exit or fuel fill. (e) The exhaust system on a gas-powered chassis shall be properly insulated from fuel tank connections by a metal shield securely attached at each point where it is 12 inches or less from tank or tank connections. (f) The muffler shall be constructed of corrosion-resistant material. (g) The exhaust system may be routed to the left of the right frame rail to allow for the installation of a lift on the right side of the vehicle. (9) Frame. (a) The frame (or equivalent) shall be of such design and strength characteristics as to correspond at least to standard practices for trucks of the same general load characteristics which are used for highway service. (b) Any secondary manufacturer that modifies the original chassis frame shall guarantee the performance of workmanship and materials resulting from such modification. (c) Frames shall not be modified for the purpose of extending the wheelbase. (d) Holes in top or bottom flanges or side units of frame, and welding to frame shall not be permitted except as provided or accepted by the chassis manufacturer. (e) Frame length shall be established in accordance with the design criteria for the complete vehicle. (10) Fuel Tank. (a) Fuel tank (or tanks) having a minimum 30-gallon capacity shall be provided by the chassis manufacturer. The tank shall be filled and vented to the outside of the body and the fuel filler should be placed in a location where accidental fuel spillage will not drip or drain on any part of the exhaust system. (b) Fuel lines shall be mounted to the chassis frame in such a manner that the frame provides the maximum possible protection from damage. (c) The fuel system shall comply with FMVSS No. 301. (d) Fuel tank(s) may be mounted between the chassis frame rails or outboard of the frame rails on either the left or right side of the vehicle. (e) The actual draw capacity of each fuel tank shall be a minimum of 83% of the tank capacity. (f) Installation of alternative fuel systems, including fuel tanks and piping from the tank to the engine, shall comply with all applicable fire codes in effect on the date of manufacture of the bus. (11) Horn. Buses shall be equipped with a horn or horns of standard make, each horn capable of producing complex sound in bands of audio frequencies between 250 and 2,000 cycles per second and tested per Society of Automotive Engineers Standard J377. (12) Instruments and Instrument Panel and Ignition Lock. Chassis shall be equipped with the following instruments and gauges or warning lights: (a) Speedometer. (b) Odometer which will give accrued mileage, including tenths of miles. (c) Voltmeter. Ammeter with graduated charge and discharge with ammeter and its wiring compatible with generating capabilities is permitted instead of voltmeter or warning light. (d) Oil-pressure gauge and/or warning light. (e) Water temperature gauge and/or warning light. (f) Fuel gauge. (g) High beam headlamp indicator. (h) Brake indicator gauge (vacuum or air). Light indicator instead of gauge is permitted on a vehicle equipped with hydraulic-over-hydraulic brake system. If ABS equipped, must have indicator light. (i) Turn signal indicator. (j) Glow-plug indicator light where appropriate. (k) Ignition lock, key or device to prevent starting of the engine by an unauthorized person. (l) All instruments shall be easily accessible for maintenance and repair. (m) Instruments and gauges shall be mounted on the instrument panel in such a manner that each is clearly visible to the driver while in a normal seated position, in accordance with School Bus Manufacturers Institute School Bus Design Objectives, January, 1985. (n) Instrument panel shall have lamps of sufficient candlepower to illuminate all instruments and gauges and shift selector indicator for automatic transmission. (o) Vehicles with an automatic transmission shall be equipped with a neutral safety switch to prevent starting in any gear other than park or neutral. For vehicles with a standard transmission clutch, pedal must be depressed to start vehicle. (13) Openings. All openings in the floorboard and the firewall between the chassis and the passenger-carrying compartment, such as for gearshift selector and parking brake lever, shall be sealed. (14) Shock Absorbers. Buses shall be equipped with front and rear double-action shock absorbers compatible with manufacturer's rated axle capacity at each wheel location. (15) Springs. Capacity of springs or suspension assemblies shall be commensurate with chassis manufacturer's gross vehicle weight rating. (16) Steering Gear. The steering gear shall be approved by the chassis manufacturer and designed to assure safe and accurate performance when the vehicle is operated with maximum load and at maximum speed. (a) Steering mechanism must be accessible to accomplish any required external adjustments. (b) No changes shall be made in the steering apparatus unless approved by the chassis manufacturer. (c) There shall be clearance of at least two inches between steering wheel and cowl instrument panel, windshield or any other surface. (d) Power steering is required and shall be of the integral type with integral valves. (e) The steering system shall be designed to provide means for lubrication of all wear-points that are not permanently lubricated. 32 (17) Tires. All tires must have a minimum tread depth of / inch. Reject all tires with less 4 32 than / inch tread depth when measured at any point in a major tread groove. 4 (18) Undercoating. A chassis manufacturer shall coat the undersides of front fenders with rustproofing compound. The compound manufacturer must issue to the chassis manufacturer a notarized certification that the compound meets or exceeds all performance and qualitative requirements of Federal Specification TT-C 520b, paragraph 3.4 (General Services Administration) using modified test. (19) Weight Distribution. Weight distribution of a fully loaded bus on a level surface shall be within the manufacturer's front gross axle weight rating and rear gross axle weight rating. (20) Wiring. All wiring shall comply with applicable recommended practices of the Society of Automotive Engineers.