SIDEBAR: Shining See

The trailer lighting market is experiencing its biggest era of change since sealed-beam units came into use decades ago, thanks to the introduction in the late 1980s of light-emitting-diode (LED) technology. In operation, LEDs shine over traditional filament-based incandescent lamps. They’re more vivid and bright, draw less power, and react more quickly when called upon. Truck and trailer OEMs have increasingly taken notice of LEDs for marker and signal lighting, offering them as standard options. On tractors, in fact, the Volvo VN’s cab-roof marker array started out as a standard option with LEDs and now has evolved to where this style of lamp is the standard specification.

But if LEDs are lights fantastic, how come they only snagged about 10% of the lighting spec’d for trailers in North America last year?

Brad Van Riper, vice-president of research and development at Truck Lite Co., calls it “perceived initial cost”-in plain language, “sticker shock.” LED lights today cost about five times as much as incandescent, Van Riper says. That’s better than 10 years ago when they were typically 10 times more expensive, but still too rich for the blood of most equipment buyers.

But prices are starting to fall, and for two reasons. One is market acceptance. Fleet managers are buying into the idea that LED lighting is an investment that will pay off over time. A typical incandescent unit has a life of about 5000 operating hours for tail lights, and 1500 hours for stop lights. That’s eight to 10 times as long as incandescent lamps, manufacturers say, so chances are an LED lamp won’t burn out during the trailer’s entire life. And being solid-state, LEDs resist the effects of shock and vibration and draw much less power to provide the same amount of brightness.

The second reason prices are dropping is that the technology is improving.

“Back in 1992, we had a stop/tail/turn light for trailers that required 62 diodes inside it,” says Van Riper. “Nowadays, lighting suppliers are producing lamps that require as few as 10 to 17 diodes to do the same job.” The fewer diodes you need, the less the overall lamp will typically cost.

And the less space it will take up on the vehicle. LED lamps can often fit better than incandescent in the top-of-the-frame area recently “re-mandated” by the U.S. National Highway Traffic Safety Administration for the trio of identification lights on a trailer’s rear end. (Given the frame-depth constraints of some van-body designs, over the years the positioning of these lights had in some cases moved down a fair bit from the roof line, but an October 1999 ruling firmly clarified the requirement for these to be at the very top of the frame.)

Another LED advantage is the low-current requirements. LEDs draw only one-tenth the amps of incandescents, and this is becoming important as antilock braking systems begin appearing on trailers. The industry has agreed that a minimum of 9.5 volts should be available at the rear of the trailer. The easiest, most reliable way to get that in double- and triple-trailer combinations, without going to heavier, more expensive wiring, is to use LED lamps.

For a typical 53-foot van trailer with just the basic, legally required suite of exterior lighting, an incandescent system would draw 18 amps and 230 watts; the same system using LEDs would demand just 2.8 amps and 36 watts.

Finally, LED lamps come on to full brightness marginally faster than incandescent, which could mean earlier perception of brake-light activation and therefore a vital few feet more in stopping distance if you’re the one who’s behind the trailer in question.

However, there are still legitimate concerns about LEDs. Maximum service life remains something of a question mark. With their demonstrated ability to handle shock and vibration-the culprits that damage filaments and shorten the life of incandescent bulbs-some enthusiastic marketing literature over the years has claimed a 100,000-hour illumination life for LEDs. This may be true, but since so few units have actually been in service enough years to get anywhere near to that level, their real-world (as opposed to lab) performance has yet to be confirmed.

While market acceptance slowly builds, research and development of new technology is steaming ahead to keep up with changes to vehicles, says Ed Bukowski, vice-president of engineering, at Grote Industries in Madison, Ind. “There’s research looking at going to a higher-than-12-volt vehicle electrical system. One serious proposal is looking at a 48-volt system, where you’d end up with about 42 volts usable power, which would allow smaller batteries and smaller starters.

“If you wanted to keep using incandescent lights with such a system, you’d have to reduce filament thickness, and then resistance to shock and vibration would be diminished. With LEDs you’d just have to alter the resistor-diode values. I expect such higher-voltage systems to show up first in cars-probably within the next three years-and then in commercial trucks and trailers around 2008 to 2010.”

Bukowski notes that there are options in addition to LEDs for such a higher-voltage environment, too: gaseous-discharge lamps, fluorescent, neon, and even “distributed lighting systems,” where there would be one central light source whose output was distributed by fiber-optic cable to the required illumination locations.

“For example, there’s R&D under way now to use fluorescent technology for centre-high-mount stop lamps in passenger cars, and I understand some experiments are being done with neon for various applications,” he says. “This hasn’t been focused on commercial vehicles yet as far as I know, but it’s probably just a matter of time.”


The North American trailer lighting market-whether incandescent or LED-is overwhelmingly supplied by just four firms. Here are a quick look at them and their products:

o Federal-Mogul, Southfield, Mich. The Signal-Stat 4070 Series of sealed incandescent signal and back-up lamps now incorporates “Fat Cartridge” bulbs (with minimal internal components and potential failure points) and an advanced silicone shock-mount bulb cradle.

o Grote Industries, Madison, Ind. and Scarborough, Ont. The SuperNova series of round, clearance/marker, and stop/tail/turn LED lamps offers easy retrofitting to replace incandescent installations, since they use the same mounting patterns and lamp-to-harness connections. A line of two- and 2-1/2-inch “beehive” red and yellow clearance/marker LED lamps has also been introduced.

o Peterson Mfg., Grandview, Mo. The Piranha line of 10-diode LED stop, turn, and tail lights replaces an earlier line that required 39 diodes, with this reduction made possible by a more efficient optic-lens design and brighter diodes.

o Truck-Lite, Falconer, N.J. The Model 15 and Model 19 families of narrow-profile red or yellow LED clearance/marker lamps are designed for areas where mounting space is at a premium, offering dimensions of 1-1/4 inches wide by 2-1/2 to 3-3/4 inches long. These units are direct replacements for the firm’s earlier Model 15 and 19 incandescent lamps.

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