There is a chance that an automobile owner needs to adjust the headlamp aim of the vehicle headlamp assembly. Sometimes it is simply because the owner prefers higher or lower beams. Other times, for safety reasons, it is important to avoid directing the headlamp aim in a direction that may shine directly into the eyes of oncoming traffic. Recognizing these needs, manufacturers make most headlamp assemblies incorporating a means of adjusting the headlamp aim relative to a given vehicle configuration.
In the past, many headlamp assemblies were designed so that the entire headlamp assembly (lens, headlamp, and housing) could be tilted for a desired aim. However, it is often desirable to have a headlamp assembly that is flush mounted and follows the contours of the vehicle's body panels to enhance aerodynamics or styling, and the seam where the headlamp's circumference meets the vehicle's body sealed so the vehicle's inner body and/or electrical components are protected from water. Thus, modern headlamps have a fixed outer headlamp lens, and movable reflector, bulb, and other components. In a headlamp assembly with a fixed outer lens, the headlamp typically can be tilted within the housing relative to the fixed outer lens for headlamp aim adjustment.
Various adjustment mechanisms for adjusting headlamp aim have been disclosed. Past and current adjustment mechanisms have an adjustment screw that engages with either the vehicle chassis or the headlamp assembly to push/pull the headlamp actuating a tilt in the headlamp relative to the vehicle chassis or relative to the headlamp assembly in a fixed lens assembly. In the past, the adjustment screw was typically turned by engaging the screw head with a tool directly. For example, many headlamp adjustment mechanisms found on passenger cars and pickup trucks have at least one adjustment screw that has a slot formed in the screw head adapted to receive a phillips-head screwdriver.
For headlamp assemblies without a fixed outer lens, the headlamp aim can be adjusted from outside the vehicle with a screwdriver directly. Other vehicle configurations only provide access to the headlamp adjusters from within the engine bay, which means the hood needs to be open during adjustment. For headlamp assemblies with a fixed outer lens, the headlamp adjusters must be accessed from within the engine bay area, from the backside of the body panel, or from underneath the vehicle because the adjuster is only accessible from the rear of the vehicle.
Obviously the cumbersome accessibility hinders the vehicle maintenance and repair, and increases repair cost. Furthermore, in some configurations, for example, vehicles with their headlamp assemblies are mounted to the hood, the requirement that the hood must be open would not be very practical because it is impossible to adjust the headlamp's aim when it was in a high up position with the opened hood, and pointing at a different direction other than the horizontal direction. Thus, in such vehicle configurations, it is desirable to adjust the headlamp's aim when the headlamp is in its normal operating position, somewhat horizontal to the ground; i.e., with the hood closed.