Code of Maryland Regulations
Title 11 - DEPARTMENT OF TRANSPORTATION
Subtitle 14 - MOTOR VEHICLE ADMINISTRATION-VEHICLE INSPECTIONS
Chapter 11.14.04 - Safety Standards for Trucks, Truck Tractors, Commercial Buses, and Type I School Vehicles
Section 11.14.04.12 - Lighting

(3) Preparation for Headlamp Aim Inspection. Preparation for headlamp and aim inspection is to be done by owner of vehicle before inspection. Frame leveling and wheel alignment inspection is done before inspection. Frame leveling and wheel alignment inspection is done at the station. Any one of the items listed below can affect the inspection results and may cause rejection of the vehicle. To prevent this and reduce inspection time, the owner should have the first three items completed before inspection.

(1) High Beam. Vehicle shall be equipped with either the dual headlighting system consisting of four 5 1/4-inch diameter units, two of which shall be No. 1 and two of which shall be No. 2; or four 6 1/2 x 4 1/2 inch rectangular units, two of which shall be No. 1A and two of which shall be No. 2A; four 5.93 x 3.64-inch rectangular-type F units, two of which shall be LF units and two of which shall be UF units; or a single headlighting system consisting of two 7-inch units; or two 8 x 5 inch rectangular units; or an approved bulb and reflector-type system. All units bearing the marking No. 2 shall be inspected and aimed on low beam. All units bearing the marking No. 1 or no number shall be inspected and aimed on high beam. Headlamp inspection and aiming by the photoelectric-optical method, not applicable to school vehicles, requires a level area sufficient for the vehicle and test equipment. The test equipment shall be accurately calibrated to the floor and accurately aligned to the vehicle. Additional lighting information is contained in §§E, F, and G (limits are in inches at 25 feet). Labeling requirements for sealed beam headlamps manufactured on or after July 1, 1979: 5 3/4 inch type 1-1C1, type 2-2C1; 6 1/2 inch by 4 1/2 inch type 1A-1A1, type 2A-2A1; 7 inch type 2-2D1; 8 inch by 5 inch type 2B-2B1; type F 5.93 inch by 3.64 inch-low beam-LF, high beam-UF. Type F units require a special aimer adapter and must be aimed in accordance with the manufacturers' recommended procedures. Bulb and reflector-type headlamps currently approved contain a 9004 Sylvania bulb in a normal reflector unit or an H-4 bulb in a sealed reflector unit. Sealed reflector units contain a glass bubble which encases the bulb when in place which can be detected by removing the bulb and determining if the bubble exists.

Agency Note: Labeling requirements for sealed beam headlamps manufactured on or after July 1, 1979: 5 3/4 inches Type 1-1C1, Type 2-2C1; 6 1/2 inches by 4 1/4 inches Type 1A-1A1, Type 2A-2A1; 7 inches Type 2-2D1; 8 inches by 5 inches Type 2B-2B1

Figure 28.

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Figure 29-TYPE 1-SCHOOL VEHICLE HEADLAMP CONFIGURATIONS.

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(2) Low Beam. Inspect the low beam headlamp in the same method as indicated for high beam. Always inspect the following sealed beam units on low beam only: 5 3/4 inch diameter or 6 1/2 x 4 1/4 inch rectangular marked type 2 or 2A and 7 inch diameter or 8 x 5 inch rectangular marked type 2 or 2B.

(1) To compensate for the various conditions of loading encountered during inspection, the frame or body floor shall be made level before checking. This will provide a standard condition for inspecting all vehicles and may be accomplished by using a combination of blocks under the rear wheels or a lifting device (jack) or both for the front end. A spirit level may be laid along the frame side member.

(2) Place vehicle in a darkened location of sufficient size for the vehicle and an additional 25 feet from lamps to screen. Level the vehicle frame as described in §C(1). The vehicle shall be located accurately in front of the screen. An approved marked screen and adequate test area are required.

Figure 30-AIMING SCREEN BEAM PATTERN-HIGH BEAM.

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(3) Inspect the low beam headlamp in the same method indicated as for high beam. Always inspect the following sealed beam units on low beam only: 5 3/4 inch diameter or 6 1/2 x 4 1/4 inch rectangular units marked type 2 or 2A and 7 inch diameter or 8 x 5 inch rectangular units marked type 2 or 2B.

Figure 31- AIMING SCREEN BEAM PATTERN-LOW BEAM.

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(1) "Asymmetrical beam" (nonsymmetrical) means a beam in which both sides are not symmetrical with respect to the median vertical plane of the beam. All lower beams are asymmetrical.

(2) "Back-up lamp" means a lamp used to provide illumination behind the vehicle, and to provide an indicator when the vehicle is in reverse gear.

(3) "Clearance lamp" means (on trucks and buses 80 inches or more wide) a lamp which shows to the front or rear of a vehicle, mounted on the permanent structure of the vehicle as near as practicable to the upper left and right extreme edges to indicate overall width and height of the vehicle.

(4) "Cornering lamp" means a steadily burning lamp used when the turn signal system is operating to supplement the headlamps by providing additional road illumination in the direction of the turn.

(5) "Driving lamp" means the auxiliary lamp or lamps that may be used to supplement the upper beam of the regular headlamps.

(6) "Emergency warning lamp" means a lamp which provides a flashing light to identify an authorized vehicle on an emergency mission. The emergency signal may be an oscillating lamp, a rotating beacon, or pairs of alternately or simultaneously flashing lamps.

(7) "Fog lamps" means a lamp which may be used with the lower beam headlights to provide illumination under condition of rain, snow, dust, or fog.

(8) "Hazard warning lamp" means a turn signal lamp which flashes simultaneously to warn of the presence of a vehicular hazard.

(9) Headlamps.

(10) "Headlamp lower beam" means a distribution of light so directed as to avoid glare in the eyes of oncoming drivers while providing illumination ahead of the vehicle and intended for use in congested areas and on highways when meeting other vehicles within a distance of 500 feet.

(11) "Headlamp upper beam" means a distribution of light intended primarily for distant illumination and for use on the open highway when not meeting other vehicles.

(12) "Identification lamps" (on trucks and buses 80 inches or more wide) means lamps used in groups of three, in a horizontal row, which show to the front or rear or both, having lamp centers spaced not less than 6 or more than 12 inches apart, mounted on the permanent structure as near as practicable to the vertical centerline and the top of the vehicle, to identify certain types of vehicles.

(13) "Indicator lamp" means a lamp visible to the operator of a vehicle that indicates:

(14) "Lane changer" means a device, usually incorporated in the turn signal switch which will actuate the turn signal lamps when held by the driver. It is intended for momentary use for signaling a lane change. When released by the operator, it will return to neutral and de-activate the signal lamp.

(15) "License plate lamp" means a lamp used to illuminate the license plate on the rear of a vehicle.

(16) "Operating units or switches" means devices by which the functioning lamps are controlled.

(17) "Parking lamp" means lamps used to designate the front of a parked vehicle.

(18) "Passing lamp" means an auxiliary lamp or lamps that may be used to supplement the low beam of a standard headlamp system. It is not intended for winding roads or congested city areas.

(19) "Reflective devices" means a device used on vehicles to give an indication to an approaching driver by reflected light from the headlamps of approaching vehicles.

(20) "SAE Lighting Identification Code" means a series of standardized markings for lighting devices which a manufacturer or a supplier may use to mark his product to indicate the SAE lighting standard or standards to which the device is designed to conform. The code is not intended to limit the manufacturer or supplier in applying other markings to the devices.

(21) "Sealed beam headlamp assembly" means a major lighting device used to provide general illumination ahead of the vehicle. It consists of the following:

(22) "Sealed beam unit" means an integral and hermetically sealed optical assembly with the name "Sealed Beam" molded in the lens.

(23) "Side marker lamp" means a lamp on the left and right sides, beamed to the side, and intended to indicate vehicle length. They are located near the front and rear on each side and, for vehicles over 30 feet in length, are also located at the midpoint (intermediate side marker).

(24) "Stop lamp" means a lamp giving a steady warning light to the rear of a vehicle, to indicate the intention of the operator of the vehicle to reduce speed or stop.

(25) "Symmetrical beam" means one in which both sides are symmetrical with respect to the median vertical plane of the beam. Lamps having symmetrical beam are:

(26) "Tail lamp" means a lamp used to designate the rear of a vehicle.

(27) "Turn signal lamp" means a lamp which provides a flashing warning light to indicate the intended direction of the turn.

(1) The following list is an identifying code for lights and signaling devices:

(2) All equipment for testing headlamps shall comply with the Society of Automotive Engineers Recommended Practice for Headlamp Inspection Equipment.

(1) Headlamp Testing Machine. When a headlamp testing machine is used, it shall give results equivalent to those obtained using a screen. It shall be in good repair and adjustment, and shall be used in accordance with the manufacturer's instructions. A machine using a photoelectric cell or cells to determine aim should also have a visual screen upon which the beam pattern is projected proportionally to its appearance and aim on a screen at 25 feet. The visual screen shall be plainly visible to the operator and have horizontal and vertical reference lines to permit visual appraisal of the lamp beam.

(2) Mechanical Aimer (applicable to school vehicles only). When a mechanical aimer is used, it shall be in good repair and adjustment, and shall be used according to the manufacturer's instruction and shall be calibrated to the slope of the floor on which the vehicle stands.

(3) Screen (applicable to school vehicles only). When a screen is used, it should be 5 feet high x 12 feet wide with a matte white surface well shaded from extraneous light, and properly adjusted to the floor on which the vehicle stands. Provisions may be made for moving the screen so that it can be aligned parallel with the rear axle so that a horizontal line drawn perpendicularly from the centerline of the screen will pass an equal distance midway between the two headlamps. The screen shall be provided with a fixed vertical centerline, two laterally adjustable vertical tapes, and one vertically adjustable horizontal tape.