Running overweight spells fines, running underweight spells lost potential revenue and running all over the place looking for a scale platform spells wasted time and yet more overhead. In an elegant avoidance manoeuvre, however, tens of thousands of trucks have on-board scales that let drivers avoid all three scenarios.

On-board scales have been around for three decades but the appearance of air suspension and lower costs have helped their expansion beyond niche markets into more mainstream fleets.

On-board scales can reduce liability associated with accidents involving overweight loads; avoid overweight fines; reduce out-of-route miles and waiting time driving to scale platforms; reduce maintenance; help companies prepare more accurate billing; and maximize loads.

On-board scales have two parts: The first are the load sensors, which can be mounted over spring suspensions, in hydraulic systems to measure fluid flow or spliced into air suspension lines to measure an increase in compensating air pressure as a trailer is loaded. The sensors can be mounted in trailers or the tractor and, depending on the number installed, can measure the total tractor and trailer weight, or the weight on individual axles.

The second part of the system is called the meter, which is the brain of the system. It collects and interprets the data from the sensors and displays it to the driver. Some are installed externally on trailers, some are dash-mounted and others are hand-held, battery-operated units.

On-board scale manufacturers offer various solutions to fit fleets with mixed suspension types of company and owner-operated trailer and tractor mixes. For example, Weigh-Right Incorporated, in Kansas, recently installed its Easy Air II system in over 4,000 tractors and trailers belonging to Prime Inc. of Springfield, Missouri. Most of the drivers are owner-operators with their own tractors, and they have been buying the hand-held Easy Air II meters, which connect with any of the sensors installed in the Prime trailers. “When the guy wants to scale the truck, he carries his meter back to the trailer and connects it to the quick connect port,” says Weigh-Right president Dave Dohrmann.

On-board scales can be ordered from the original equipment manufacturer as well as purchased as after-market add-ons. For example, Air-Weigh Scales, in Oregon, does 60% of its business selling its scale systems as a standard production option on trailers from 67 trailer manufacturers. Also, says Peter Powell, Air-Weigh’s vice president marketing, “we are working with all but one of the North American truck manufacturers to integrate Air-Weigh data into their in-dash displays. You will begin to see those appear in price book options beginning this fall and in the first quarter of 2004.”

Vulcan On-Board Scales, located near Seattle, Washington, sells two different meters that can read off the same tractor and trailer-mounted sensors. The Vulcan V600, says Eric Elefson, Vulcan’s director of sales and marketing, “has additional display capabilities and the ability to communicate with other smart devices. It can store and transmit to, say, a computer.” This is useful if load information has to be incorporated into a billing system. For over-the-road work, where weights need only be displayed to check weight limits, the Vulcan V300 is sufficient.

What should a fleet look for in an on-board scale system? It needs to match a system to its needs; for example, the ability to transmit weight data over a communications system to home base. If one’s freight is always going to be a legal gross vehicle load, a trailer-mounted scale and meter system may be all that is necessary to balance out the load. “The customers should interview companies and hold them responsible for proving what they have done. Check the references and background of the scale provider,” advises Elefson.

The biggest emerging trend may be the integration of scale systems with on-board computers and the ability to display weight data on existing dash displays. One day, weight will simply be one of many variables monitored by trucks’ electronic systems.