LEDs for heavy trucks and commercial vehicles

The proportion of LED lamps used in commercial vehicles is rising and LEDs will largely replace incandescent lamps in a few years.

Feb 15th, 2005
Content Dam Leds En Articles 2005 02 Leds For Heavy Trucks And Commercial Vehicles Leftcolumn Article Thumbnailimage File
The heavy truck market is very important to the health of the world’s economy. In the United States, nearly 60% of all cargo - over 9 trillion tons annually - is transported by road. A mixture of large and small truck fleets and individual owner-operators handles all of this freight.

LED marker lamp
The lighting for vehicles used in this market has its own unique set of requirements and challenges. This article will explain what the challenges are, why LED lights are well-suited to these requirements, and what the future looks like for LED lights in the trucking industry.

Lighting challenges

Heavy trucks and trailers provide a severe environment for lighting. Unlike lights in a typical car, the lights on a truck or trailer are often mounted on the exterior of the vehicle, so the lights and the wiring connected to them are not protected by the vehicle bodywork.

Stop/tail/turn lamp
Because of their exposed location, these lights are subjected directly to such environmental hazards as road spray, high-pressure washdowns, and corrosive chemicals. A tanker truck carrying chemicals or fuel, for example, cannot route the wiring inside the tank where it might cause a spark, so it is mounted directly on the exterior of the trailer. The lights attached to that wiring are subject to splashes of whatever substance is being carried whenever the tank is filled or emptied.

Heavy trucks can also be a high-vibration environment. One extreme example is the lights mounted on the rear of a dump truck. These lights not only undergo vibration as the truck travels on and off the road, but they also experience large shocks as loads are dropped into the truck, or as the tailgate slams closed after a load is dumped. The author was told by one dump truck driver that the bulbs in the lights on the back of his truck had to be replaced every few weeks.

In addition, heavy trucks are often on the road for many more miles and much more time than a typical passenger car. It is not uncommon for a truck to travel 100,000 miles or more in a year, and many of them leave their lights on whenever the truck is operating.

Rear lamps
The regulatory environment for heavy trucks is also a difficult one. The transportation industry is the most heavily regulated industry in the nation. Vehicles are inspected frequently, and if a required light is found to be non-functioning, the vehicle may be fined or taken out of service until the light is repaired.

Maintenance costs also have an impact on lighting for heavy trucks. When a light bulb burns out and must be replaced, the cost to the vehicle fleet is much more than just the cost of the bulb. The truck must be taken out of service, losing money that could be made on the road, and a maintenance technician must be paid for the time and equipment needed to replace the bulb.

Advantages of LED lights

LED lights can eliminate or alleviate many of the above-mentioned problems. The extremely long life of LEDs means that stops to replace burned-out bulbs are nearly eliminated. Being solid-state devices, LEDs are insensitive to shock and vibration.

Side turn lamp
The damage caused by water intrusion and corrosion can also be lessened by careful design of the LED lighting system. One part of that system is the circuit board and connections that provide power to the LEDs. Left unprotected, standard circuit boards can be easily damaged by water. For this reason, lighting manufacturers like Grote Industries encapsulate the circuit board in an epoxy potting material. Once encased in this material, the LEDs and circuit board become completely impervious to moisture.

One vulnerable part of the lighting system is the interface between the wiring harness and the lamp. If the wiring harness does not provide a good seal to the lamp, the terminals can corrode, causing it to stop functioning long before the LEDs have reached the end of their life. A properly designed lamp and harness system, like Grote Industries’ male pin lamps and UBS harness system, can eliminate this vulnerability. A study on long-term severe environment testing has shown that such a system can last 81% longer than the typical competing systems.

Another advantage of LED lamps that is very important to the trucking industry is their low power demand. Not only do trucks require a lot of electrical power, but they also need to transport that power over long distances. Large wires are required to keep electrical power losses to a minimum, especially when two or three trailers are being pulled by a single truck. With the addition of ABS braking systems a few years ago, this power demand increased. LED lamps typically use one fifth to one tenth of the power of incandescent lamps.

The market for LED truck lighting

When Grote Industries introduced the first LED marker lamp for the trucking industry in 1990, it was difficult to convince industry professionals that LED lamps were worth the extra money they cost. As those lamps began to be installed and used, however, their greater durability and long-term cost savings became apparent.

LED dome lamp
Those initial lamps were confined to low-light marker functions because the LEDs that were available at the time were not capable of producing enough light for the more demanding applications. As time passed, more powerful LEDs became available, allowing their use in stop lamps in 1994, after which they proliferated through the full line of exterior and interior lighting for both tractors and trailers.

Currently, the only vehicle lighting functions that cannot be provided by LEDs are the forward lighting functions such as headlamps and fog lamps. As LEDs continue to improve, even the forward lights will be replaced by LED lamps, with a few specialized lamps appearing this year, and more generally used lamps coming out by the end of the decade.

Along with the increase in the number of lamps available with LEDs there has also been an increase in the number of LED lamps purchased by the trucking industry. A large part of this sales growth has come through the intervention of large trucking fleets. Once these fleets realized how much maintenance costs could be reduced by using LED lights, they began specifying LED lights on all the trucks and trailers they ordered. Individual owner-operators also began installing LED lights because of their modern, up-scale appearance.

While the number of incandescent lamps sold still exceeds that of LED lamps, the proportion of LED lamps continues to increase. In a few years, incandescent lamps on a truck will be as uncommon as record players and typewriters.

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