Trailer Sensors Bring Missing Visibility to Maintenance

Sensors can show whether brakes are out of adjustment or linings are worn, which are two common violation triggers. (Julian Alexander/Cox Fleet)

Trailers are typically the less visible half of a combination vehicle, often spending days or weeks in yards, drop lots or distribution centers without being attached to a tractor. That lack of visibility can make them harder to monitor and maintain, increasing the risk that maintenance issues go unnoticed until a roadside inspection or an over-the-road failure occurs.

Fleets are increasingly turning to connected trailer technology for real-time monitoring to close that gap, gain continuous insights into trailer health and address problems before they escalate.

“Real-time trailer health data is fundamentally shifting maintenance from reactive to predictive,” said Michael Quimby, chief operating officer for Kooner Fleet Management Solutions. “It also brings trailers into the same visibility framework as powered assets, which historically hasn’t been the case.”

James Grier, director of fleet service at Nussbaum Transportation, described this technology as “another set of eyes” on trailers.

The truckload carrier has outfitted its trailers with sensors from Phillips Connect to monitor tire pressure, automatic inflation systems, tire events and brakes. It also has light-out detection on many of its trailers.

“When that driver actually shows up to pull that trailer, they’ve got a clean bill of health,” Grier said, adding that roadside events have dropped significantly and the fleet’s already-strong Compliance, Safety, Accountability score has improved further.

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With better visibility, many fleets are shifting to condition-based maintenance planning. (Phillips Connect)

For many fleets, regulatory compliance is the primary driver behind trailer sensor adoption. Brakes, lights and tires account for more than 75% of out-of-service violations during Commercial Vehicle Safety Alliance inspection events, according to Mark Wallin, general manager and senior vice president of products at Phillips Connect. Those systems are also the ones most often monitored by trailer sensors.

Tim Moore, director of fleet operations at Cox Fleet, said tire pressure and brake monitoring are especially important because both directly affect out-of-service determinations. Sensors can show whether brakes are out of adjustment or linings are worn, which are two common violation triggers.

Tire pressure monitoring also helps fleets prevent roadside failures by alerting them to slow leaks before they turn into blowouts. Catching an issue early can mean the difference between a repairable tire casing and a destroyed one, Moore said.

Randy Obermeyer, vice president of safety and maintenance for Online Transport, said real-time alerts for low tire pressure and high temperatures are particularly valuable because those problems can escalate quickly. The faster maintenance teams can respond, he said, the more damage they can prevent to tires and wheel ends.

Beyond avoiding breakdowns, maintaining proper tire pressure helps reduce premature wear and extend tire life. In addition to using tire pressure monitoring systems, Online Transport is testing sensors that provide tread depth data, which can help predict replacement needs based on remaining tread.

For fleets like Maverick Transportation, the financial case for acting on real-time data is straightforward.

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“If you wait until the tire has a catastrophic failure, you just blew $400,” said Brent Hilton, Maverick’s director of maintenance.

The same logic applies to wheel-end failures. With an early alert, he said, the issue might be resolved with a $50 wheel seal and an hour of labor. If a wheel-end meltdown occurs, however, downtime increases and axle replacement costs can climb into the $7,000 to $9,000 range, Hilton said.

Rocco Marrari, vice president of sales for telematics vendor Pedigree Technologies, said those numbers can go even higher if a fire occurs.

“We had one prospect whose tire overheated, caught fire, and they lost the entire load, their trailer and their tractor,” he said.

Data-Driven Trailer Maintenance

Trailer sensor data also helps fleets decide which issues require immediate attention and which can wait.

Phillips Connect’s Wallin said brake fault codes are a good example. A fault code does not necessarily mean a trailer is unsafe to operate, he said. Instead, fleets must understand where an issue falls on a spectrum ranging from “needs attention soon” to “pull it now.”

As fleets gain more visibility into trailer health, many are shifting from calendar-based maintenance schedules to condition-based planning.

Nussbaum Transportation is among the fleets using sensor data to refine preventive maintenance routines.

“Before, schedules were interval-based,” Grier said. “Now we’re able to fine-tune our PMs and what’s truly being addressed and at what times.”

Improved visibility can also increase efficiency inside the shop. With limited technician time and bay capacity, remote monitoring helps fleets avoid pulling trailers in solely for routine checks, said Matt Wilson, vice president of the vehicle technology group at Hendrickson. Instead, teams can focus on inspections and repairs where data indicates emerging issues.

Real-time and historical data also allow service providers to diagnose problems faster and arrive with the right parts, reducing trial-and-error repairs. That improves first-time fix rates, shortens repair cycles and enhances communication with customers, Kooner’s Quimby said.

As fleets deploy more sensors, however, data management becomes a challenge. Fleets often rely on hardware from multiple suppliers, creating complexity around integration and return on investment.

Too much data can also overwhelm drivers if alerts are not carefully filtered.

At Maverick Transportation, tire pressure information appears on in-cab displays, while other alerts, such as wheel-end conditions and lighting issues, are routed to maintenance coordinators, who then contact the driver if needed.

For more value, fleets increasingly are looking to bring information from multiple systems into a single view.

“On their own, each system provides a partial picture,” said Barry Brookins, director of sales engineering for diagnostics intelligence firm FleetHD. “The real value comes from bringing all of that data into one place where it can be correlated.”

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Products like Samsara's vehicle telematics app help fleets compile data points into one place. (Samsara)

Some fleets are combining trailer data with tractor data and driver vehicle inspection reports to add context. David Gal, vice president of connected operations for Samsara, said that approach has helped identify recurring issues such as blown antilock braking system fuses on certain tractors. By monitoring power loss to trailers at scale, fleets can pinpoint patterns that would be difficult to detect otherwise.

Return on Investment

The fleets seeing the biggest impact from smart trailer data are not necessarily those with the most sensors. Instead, they are the ones that have rebuilt their processes around what the data is telling them, said Wallin of Phillips Connect.

While brakes, lights and tires remain the primary focus, fleets are also using sensor data to monitor electrical systems and liftgate batteries. Junior Barrett, global director of business development for battery supplier Clarios, said liftgate battery failures are common because trailers often sit unused, allowing batteries to discharge.

When a trailer begins its route with a partially depleted battery, repeated liftgate use can drain it completely before deliveries are finished. Other issues, such as improper tractor-trailer connections or aging batteries that no longer reach full charge, can also contribute to failures.

Those failures often occur at customer locations, outside a fleet’s service network, where repairs are more expensive and time-sensitive, said Cagatay Topcu, vice president of connected services at Clarios.

Before, schedules were interval-based. Now we’re able to fine-tune our PMs and what’s truly being addressed and at what times.

James Grier, Nussbaum Transportation

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For many fleets, the most immediate return on investment from trailer sensors comes from avoiding unexpected repairs.

“The fastest real numbers payback comes from saving on-the-road tire, brake or wheel-end failures,” Online Transport’s Obermeyer said.

Tires are often one of a fleet’s largest expenses after fuel and labor. Even small reductions in cost per mile can translate into significant savings at scale.

Proactive maintenance can also extend the life of trailers and their components.

Nussbaum Transportation has pushed its trailer trade cycle from 10 years to 13 and expects to extend it further as asset health data continues to improve, Grier said.

Some benefits, such as improved driver safety, reduced stress and better customer service, are harder to quantify. Better uptime helps carriers meet service-level agreements and protect their reputations, Pedigree’s Marrari said.

Despite the benefits, trailer sensors still have limitations. A lack of standardized communication between tractors and trailers means many systems rely on cloud connectivity, which can create latency, connectivity gaps and additional costs, Hendrickson’s Wilson said.

Depending on the system, some tire data may only transmit when a trailer connects to a tractor or at infrequent intervals.

Certain issues also still require human inspection. Structural concerns such as frame integrity or corrosion remain difficult to monitor remotely, Kooner’s Quimby said.

The North American trailer market is still in the early stages of trailer telematics adoption compared with Europe, but interest continues to grow as fleets recognize trailers as critical assets rather than passive equipment.

Maintenance of engine-based assets may always come first, but fleets increasingly understand that trailer reliability is just as essential, said Gal of Samsara. “That trailer is what’s going to get the load to the customer on time.”