In heavy transport, the semi-trailer brakes system is not only a matter of road safety, but a critical pillar of operational efficiency. A failure in the brake system not only involves accident risks, but also costly downtime, fines in technical inspections and premature tire wear.
From Onyarbi Industries, specialists in the manufacture and distribution of high-precision components for axles and suspensions, we analyse the most recurrent failures in semi-trailer braking systems and how a preventive maintenance strategy can save your fleet.
Irregular Wear of Semi-trailer Brakes Pads and Linings
One of the most common problems of semi-trailer brakes is asymmetric wear. This occurs when one of the wheels or one of the axles brakes more intensely than the rest.
Technical causes:
Lack of lubrication in the calliper bolts: In disc brake systems, if the guide pins are gripped, the calliper does not float properly, causing a pad to constantly press the disc.
Automatic regulator mismatch: In drum brakes, a faulty slack adjuster may not maintain the necessary clearance between the lining and the drum.
Prevention with Onyarbi Industries:
The key here is the quality of the friction components of the semi-trailer brakes system. Using Onyarbi calliper repair kits ensures that the sealing and sliding elements withstand high temperatures and environmental corrosion, guaranteeing a fluid movement of the calliper.
Overheating and “Fading” of the System
The fading is the temporary loss of braking capacity due to excessive heat. In prolonged descents, the kinetic energy is transformed into heat that the disc or drum cannot dissipate.
Consequences:
Crystalisation: The friction material hardens and loses its grip coefficient.
Thermal cracks: Brake discs may have radial cracks that compromise their structural integrity.
Technical solution:
It is vital to ensure that the air cooling system of the shaft is not clogged and that the thickness of the discs is within the tolerance limits.
Air Leaks and Pressure Drops in the Pneumatic Circuit
The semi-trailer brakes system depends entirely on compressed air. A minimal leak can cause a delay in the brake response or, in severe cases, the automatic blocking of the emergency brakes (parking brake).
Critical inspection points:
Coupling sleeves: The wear of the rubber gaskets in the tractor-trailer connection.
Brake actuators (Lungs): Internal diaphragms perforated by fatigue or moisture entry.
Relay and ABS valves: The accumulation of oil and charcoal from the tractor compressor can damage the internal gaskets.
PRO Tip: Install brake actuators (lungs) from Onyarbi Industries. Our double chamber models (Spring Brake) pass rigourous fatigue tests to ensure that the force of the emergency spring acts instantly when the pressure falls below the safety levels of the semi-trailer brake system.
Problems with the ABS and EBS System
Electronics have revolutionised braking, within the semi-trailer brakes system, but adds complexity. A failure in the wheel speed sensor can deactivate the anti-lock system, increasing the stopping distance and the risk of “scissor effect”.
Common diagnosis:
Accumulation of ferrous waste: The magnetic sensor attracts metal particles that distort the signal.
Excessive distance between the sensor and the toothed crown: Due to vibrations or incorrect assembly.
To avoid these failures, it is imperative to check the condition of the ABS crowns. The crowns manufactured by Onyarbi guarantee exact dimensional accuracy, avoiding erroneous readings in the EBS control unit.
The “grip” of the Brake Levers and Camshafts
In the drum systems of the semi-trailer brakes, the camshaft is responsible for expanding the shoes. Over time, the entry of water and salt from the road oxidises the camshaft bushings.
Symptoms:
The brake gets “stuck” after releasing the pedal.
Unusual resistance to the vehicle’s advance, increasing fuel consumption.
Preventive maintenance of the semi-trailer brakes system:
It is not enough to grease; it is necessary to replace the bushings and seals when they are loose. Onyarbi Industries offers complete camshaft repair kits, with friction-resistant materials that extend the life of the axle.
Comparative Table: Preventive vs. Corrective Maintenance
| Element | Preventive Action (Onyarbi) | Risk of ignoring it |
|---|---|---|
| Pills/Filings | Visual inspection every 25,000 km | Irreversible damage to discs/drums |
| Brake lungs | Quarterly leak test | Unexpected roadblockBloqueo inesperado en carretera |
| Brake regulators | Grease with high pressure lubricant | Imbalance in braking (asymmetric braking) |
| Calliper bolts | Replacement of rubber protectors | Gripper of the calliper and loss of power |
Conclusion: Security is not an Expense, it is an Investment
The braking system of a semi-trailer is a set of interdependent components. The failure of a small checkpoint of Onyarbi Industries may seem insignificant, but its role in keeping the lubricant inside and the pollutants out is what prevents a camshaft from getting the flu at 90 km/h.
Focussing on spare parts with original equipment quality is the only way to ensure that your fleet is profitable and safe. At Onyarbi, we understand that every minute that a truck spends in the workshop is a minute that is not generating profits. Therefore, our products are designed for a “first-time-fit” installation, reducing assembly times and maximising durability.
Do you need to update the braking components of your fleet?
Explore our technical catalogue on the Onyarbi Industries website or contact our technical advisors to find the exact reference your axis needs.
