Sealed Beams

Sealed beam bulbs are complete, self-contained lighting units where the filament, reflector, and lens are permanently sealed together in a single assembly. Unlike standard bulbs where you replace just the bulb and keep the fixture, sealed beams replace the entire optical unit. This design was the dominant technology for automotive headlights for decades and remains common in agricultural equipment, heavy machinery, older vehicles, and various industrial applications.

The sealed beam design offers several practical advantages. Because the reflector is integral to the bulb and sealed from contamination, it maintains optimal optical performance throughout its life – no dust, moisture, or oxidation can degrade the reflector's effectiveness. The precise factory alignment between filament and reflector ensures consistent beam patterns. The rugged construction stands up well to vibration, shock, and harsh environments, which is why sealed beams remain popular in tractors, construction equipment, and off-road vehicles.

Common sizes follow the old Sealed Beam (SAE) numbering system that indicates beam diameter and configuration. The 7-inch round sealed beams (like 6014, 6015, 6024) were standard on countless American cars from the 1940s through 1980s. The 5.75-inch round sealed beams fit many motorcycles, some cars, and various equipment. Rectangular sealed beams (like 4×6 inch and 6×9 inch) became common in the 1970s-80s. PAR36 and PAR46 sealed beams, named for their parabolic aluminized reflector construction, serve agricultural, marine, and industrial applications.

Three main technologies exist within sealed beams. Standard sealed beams use traditional incandescent filaments – reliable, inexpensive, and adequate for most applications, though not particularly efficient. Halogen sealed beams use halogen gas around the filament to produce brighter, whiter light with better visibility, making them popular upgrades for equipment that came with standard sealed beams. Quartz halogen sealed beams take this further with quartz glass envelopes that can withstand higher temperatures, allowing even brighter output.

One important consideration with sealed beam headlights is the beam pattern designation. Some sealed beams have a single filament for either high beam or low beam, requiring two separate sealed beams per headlight assembly (a four-headlight system). Others have dual filaments that handle both high and low beams in a single unit (a two-headlight system). The beam pattern is typically printed on the lens face – understanding whether you need high beam, low beam, or dual beam is essential when ordering replacements.

LED sealed beam replacements have become available in recent years, offering dramatic improvements in efficiency, light output, and lifespan compared to incandescent or even halogen sealed beams. They draw less power (important for equipment with smaller alternators), produce less heat, and can last 25,000-50,000 hours versus 500-1,000 hours for traditional sealed beams. However, LED sealed beams cost considerably more upfront, so the decision depends on usage hours and the value of reduced replacement frequency.

Common Sizes: 7-inch round (6014, 6015, 6024), 5.75-inch round, rectangular (4×6, 6×9), PAR36, PAR46, PAR56, PAR64

Technologies Available: Standard incandescent sealed beam, halogen sealed beam (brighter, whiter), quartz halogen (highest output), LED sealed beam (maximum efficiency and life)

Applications: Automotive headlights (older vehicles), agricultural equipment (tractors, combines), construction and heavy machinery, marine searchlights, industrial lighting, emergency vehicles, off-road vehicles