Condition-based maintenance: what it is and how to apply CBM

Condition-based maintenance is a fleet maintenance method in which the decision to intervene starts from the actual state of the asset, and not from a fixed interval of time or mileage.

To know this state, the fleet needs condition data. It can come from motion, vibration and temperature sensors and other devices installed on the vehicles, or from measurements and technical inspections recorded routinely: what defines the method is the decision criterion, not a specific technology.

This data-driven approach can make maintenance decisions more precise than a fixed calendar, as long as the parameters tracked are the right ones and the operation is able to respond to what the data indicates.

Read on:

• What condition-based maintenance is and what it is for;
• Benefits of condition-based maintenance for your fleet;
• How condition-based maintenance works in the fleet;
• How to implement condition-based maintenance in the fleet.

What is condition-based maintenance and what is it for?

Condition-based maintenance is a strategy aimed at maximizing maintenance efficiency and reducing the occurrence of unexpected failures.

Its role is to keep close track of the fleet's assets — continuously, when there is instrumentation for it — to assess their current condition, instead of carrying out maintenance at fixed time intervals. No method eliminates the possibility of failure: what CBM seeks is to intervene before the observed deviation evolves into a breakdown.

This is the main point that sets this method apart from predictive maintenance, which combines the vehicle's data history and technological monitoring as the basis for analyses that try to predict when the failure will occur.

In short: condition-based maintenance responds to a deviation already observed, which has crossed a defined limit; predictive maintenance projects, from the trend in the data, how long it should take for that limit to be reached. Both depend on condition data and can coexist in the same fleet. To place them alongside more traditional routines, it is worth reviewing the types of maintenance.

This means that maintenance is only scheduled according to the actual state of the vehicle's components. In this way, condition-based maintenance allows fleets to identify problems before they become serious — as long as the parameter tracked really anticipates the failure you want to avoid.

Through this approach, the fleet can run more efficiently, reducing costs, avoiding unscheduled stoppages, extending the useful life of vehicles and improving the safety of operations. The size of this gain varies with the application, with the criticality of the chosen components and with the operation's recording discipline.

Benefits of CBM for your fleet

This method (CBM) brings together characteristics of preventive and predictive maintenance: like preventive maintenance, it acts before the breakdown; like predictive maintenance, it decides based on data from the asset itself, and not on a calendar. Here is a closer look at each benefit — and what each one needs in order to materialize:

Reduced maintenance costs

Condition-based maintenance makes it possible to identify problems at early stages, which can avoid major repairs and more expensive component replacements. When this is confirmed in practice, the effect shows up as a reduction in the fleet's maintenance costs.

In addition, scheduling the service in advance tends to make repairs more effective and can increase the vehicles' Mean Time Between Failures (MTBF) — an indicator that rises when failures become rarer, and not only when the repair is well executed.

There is a counterweight to consider: sensors, installation, integration and analysis also cost money. The math tends to work out for components that are expensive, critical or responsible for long stoppages, and not for every item in the fleet.

Increased reliability and availability

By keeping continuous track of the state of the fleet's assets, operations can become more reliable, achieving less unplanned downtime and greater availability of vehicles to meet the fleet's delivery schedules.

This gain depends on a point that often goes unnoticed: someone needs to receive the alert and have workshop time and parts available to act. An alert without the capacity to respond does not turn into availability — it only gives earlier notice of the stoppage.

Longer vehicle useful life

Condition-based maintenance makes it possible to identify problems at early stages. This results in corrections being scheduled in advance, which helps make interventions more precise.

By reducing the need for lengthy investigations and the risk of misdiagnosing problems, it also lowers the chance of secondary problems.

This, in turn, contributes to extending the useful life of vehicles, since problems tend to be corrected at the root, preventing additional complications. The limit is well known: the observed condition needs to be interpreted by someone who understands the component, otherwise the data turns into noise.

Better safety

Vehicles that receive proper maintenance are less likely to suffer failures during operations, which contributes to the safety of transport operations.

One caution here: keeping track of the condition does not replace the checks provided for in the manufacturer's recommendation and in the applicable regulations. CBM organizes the decision to intervene; it does not do away with inspection or with checking safety items.

Fuel consumption efficiency

Condition-based maintenance helps keep vehicles in proper working condition, which can lead to more efficient fuel consumption and reduce operating costs.

The effect on fuel does not come from the method itself, but from the items it keeps within the correct range — tire pressure, alignment, injection, filters. Without keeping track of these items, there is no reason to expect a consumption gain.

Optimized maintenance scheduling

Maintenance services are scheduled based on the actual condition of the vehicles, allowing more effective planning. This way, unnecessary interruptions to operations are avoided.

In practice, this changes the routine of maintenance planning and control (MPC): instead of a fixed list by mileage, the service queue is ordered by the state of the assets and the criticality of each deviation.

Environmental sustainability

With vehicles always operating in good condition, the fleet's environmental footprint tends to be reduced, because the emissions of gases released by burning fuel end up being reduced by the full functioning of the engine components.

The environmental gain also appears on the materials side: components that last longer and overhauls done at the right time reduce the number of parts discarded over the year.

How does condition-based maintenance work in the fleet?

This type of vehicle maintenance control usually works through advanced monitoring technologies. Among them are motion, vibration and temperature sensors and other technological devices deployed on the vehicles.

These technologies collect real-time data on the performance of the fleet's assets and transmit this data to a management system, where it is analyzed in an automated way.

Based on this analysis, the system is able to identify deviations from the expected operating conditions and flag when a maintenance intervention may be necessary. The final decision remains technical: the system points out the deviation, and it is up to the team to confirm the cause before scheduling the service.

Not every fleet starts from full instrumentation. Where a sensor is not viable (because of cost, the vehicle's age or the type of component), the condition can be captured by inspection routines with recorded measurement: tread depth, pressure, play, temperature, fluid level and appearance. The principle is the same: measure, compare with a limit and decide.

Two limits of the method deserve mention. The first is the reference: without a baseline of what is normal for that asset, any reading seems acceptable. The second is the calibration of the limits — a poorly set alarm generates false alerts, and repeated false alerts make the team stop paying attention.

Condition-based maintenance also works as a complement to Reliability-Centered Maintenance (RCM), which helps define which functions and failure modes deserve to be tracked before the fleet decides what to instrument.

How do you implement condition-based maintenance in the fleet?

Implementing condition-based maintenance (CBM) in the fleet requires careful planning and well-defined stages:

1 – Define the objectives and KPIs

First of all, it is essential to define the objectives and the key performance indicators (KPIs). This involves setting clear goals, such as reducing maintenance costs, increasing fleet availability or extending the useful life of vehicles.

For a precise definition of objectives, it is essential to carry out a comprehensive analysis of your operations and fleet vehicles. You need to identify the main difficulties and problems faced, which must be resolved to achieve substantial improvements.

This way, you will be able to set realistic and targeted goals, optimizing the effectiveness of this maintenance approach in your fleet.

Record the current value of each indicator before starting. Without this starting point, there is no way to know later whether the change came from CBM or from another change in the operation, such as a change of route, supplier or load profile.

2 – Select the necessary tools

The next step is to identify and acquire the tools and equipment needed for condition-based maintenance to happen.

Generally speaking, it is not necessary to monitor everything, but rather what is most essential for the fleet's availability, such as the functioning of the vehicles' engines.

Therefore, focus on the tools that make the most sense and that also contribute to achieving your defined objectives.

When comparing alternatives, look less at the feature list and more at three questions: does the data arrive reliably, is it comparable over time and can the team use it in day-to-day decisions?

3 – Define the critical parameters of the assets

A fundamental stage is to define the critical parameters of the assets and establish the alarm or notification limits for each one. This means determining which measurements are indicative of problems and defining what signals the need for intervention.

These limits should come from the manufacturer's technical recommendation and the asset's own history, and not from a number chosen for convenience. It is worth separating two levels: the attention level, which enters the scheduling queue, and the stop level, which takes the vehicle out of operation until the service is done.

4 – Deploy the sensors and monitoring systems

Deploying sensors and asset monitoring systems is the next stage, enabling real-time data collection.

Based on this data, CBM systems can automatically alert when an out-of-limits condition is detected, allowing an immediate response.

Start with a pilot: a small group of vehicles and a few parameters, with the response flow defined — who receives the alert, who confirms the diagnosis and how the work order is opened. Only after the cycle works from start to finish is it worth extending it to the rest of the fleet.

Once implemented, condition-based maintenance needs to be continuously evaluated and adjusted to ensure its effectiveness over time. Periodically review the parameters tracked, the limits defined and the alerts that were not confirmed: it is this review that keeps the routine from turning into bureaucracy.

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