What Are Commercial Vehicle Weighing Systems and How Do Onboard Scales Work?

Commercial vehicle weighing systems measure how much a truck, trailer, or combined rig weighs while it is being loaded and while it is on the road. The onboard version uses load cells and strain gauges mounted on the vehicle to report axle and gross weight in real time, so a driver or fleet manager can see the load before leaving a site. This differs from a fixed weigh station or truck scale, which weighs a vehicle only when it drives onto a platform at a specific location. Onboard systems are most useful for operations that need to load to the legal limit every time, avoid overweight fines, and skip scale-line waits — particularly in general trucking, waste, aggregate, and timber work.

Onboard scales vs. fixed truck scales

The two are not mutually exclusive. A fleet can use onboard scales to load accurately and still pass through fixed scales for regulatory checks.

How onboard scales measure weight

The measurement chain in a Vulcan onboard system runs from the strain gauge through the load cell to the instrumentation, and VPG states that every part of every system — strain gage, load cell, EDOC coating, and instrumentation — is designed, manufactured, and supported in-house.

1. Strain gauges are bonded to a structure that flexes under load.
2. Load cells convert that mechanical strain into an electrical signal proportional to the weight carried.
3. Instrumentation in the cab translates the signal into axle and gross weight readings the driver can act on.

Because the sensors are on the vehicle, the reading updates as material is added or removed. That is what makes it possible to load to the maximum legal weight quickly rather than guessing and correcting at a scale.

What onboard weighing changes in daily operation

The benefits below come from Vulcan's own description of its onboard scale line:

• Maximize payload. Load to the maximum legal limit every time instead of leaving capacity unused out of caution.
• Avoid overweight fines. Keeping weights within legal limits removes a direct cost and a compliance risk.
• Cut loading and readjustment time. An accurate load weight eliminates waiting in scale lines and the chance of having to remove material after a check.
• Lower maintenance costs. Properly loaded vehicles reduce wear on brakes, tires, suspensions, and related equipment, which can extend vehicle life.
• Reduce liability exposure. Avoiding overweight vehicles can significantly reduce liability in the event of an accident, and keeping weights legal can improve vehicle stability and safety.

Suspension compatibility and fleet flexibility

Vulcan offers solutions for air, spring, and mixed suspensions. The practical effect is that fleets can mix and match tractors and trailers as needed without adjusting the weighing system for each combination — useful when equipment is pooled rather than assigned to a single driver or route.

Where these systems are used

Vulcan reports its scales are proven in tens of thousands of trucks across every trucking industry, with named applications in:

• General trucking and delivery
• Waste and refuse
• Aggregate
• Timber and forestry
• Aerospace, marine, medical equipment, heavy machinery, and process control

The company states its solutions are used in 30+ countries, that it has been innovating in integrated weighing for over 40 years, and that its systems are designed and assembled in the US. If your operation loads bulk material by volume or by guesswork, an onboard system is the category to evaluate; if you only need a weight reading at a fixed point, a platform scale is the simpler fit.