Powering asphalt production

ACCORDING TO the European Asphalt Pavement Association (EAPA), the European road network consists of over 5.5 million kilometres of roads, and over 90 per cent of this is paved with asphalt. Asphalt is a mixture of aggregates and bitumen primarily used in road construction due to its durability and reliability. During production, these aggregates are dried, screened and mixed with bitumen.

There are currently around 4000 asphalt plants in Europe producing 300 million tonnes per year and at this scale reliability is non-negotiable. However, in an asphalt plant, the drive systems in the machinery required to carry out key processes are subjected to constant torque demands from heavy rotating drums and material conveyors.

At the same time, dust and abrasive particulates accelerate wear, placing strain on seals, bearings and lubrication systems. Standard drives often struggle in these conditions, but a carefully engineered approach can significantly extend equipment service life and improve reliability.

Reliable operation in challenging environments

High ambient and process temperatures mean that motors and gear units that can operate reliably under thermal stress are essential, as depending on the type of asphalt, the temperature can range from 100-190°C.

Using the right lubricant is key under these conditions, as for every 10-5 °C increase in temperature, the life of the lubricant is typically halved. Considering operating temperature and ensuring that appropriate high-temperature lubricants are used to protect critical bearing surfaces is one way that engineers can keep asphalt production machinery running under heat and load. Robust sealing solutions can also prevent heat-induced degradation of components and ensure smooth bitumen handling in the mixer and transfer lines.

Ensuring reliable operation at elevated temperatures also depends on choosing motors and gearboxes that are designed for continuous heavy loads and effective heat dissipation. Gearboxes like the Bonfiglioli 300 Series heavy-duty planetary gear unit can provide the high torque density and mechanical robustness needed for asphalt plant applications where load and temperature are combined.

Helical bevel and parallel shaft gearmotors are also a good choice, offering compact designs for operations where space may be limited, along with efficient power transmission and improved heat management to maintain performance even in the harshest conditions.

Managing shock and load variability

Torque surges are another major challenge in asphalt mixing operations. Drum mixers and conveyors frequently experience sudden load changes during start-up or when material flow fluctuates. Without proper control, these surges can cause mechanical shock and accelerate wear on gearboxes and bearings.

To address this, plant managers can integrate intelligent drive control solutions such as variable speed drives (VSDs) and motor control systems. By precisely managing acceleration, speed and torque, VSDs reduce start-up stress by gradually increasing the voltage and frequency, providing a ‘soft start’ that can protect machinery from damaging shock loads.

Advanced control systems also allow operators to adapt to changing process conditions in real time. Adjusting motor speed to match material flow not only improves reliability but can also enhance energy efficiency and process consistency by limiting unnecessary energy usage.

Asphalt mixing plants will always push drive systems to their limits. However, with a carefully chosen combination of high-performance motors, durable gear units and smart drive control, the limits can be managed effectively. The right solutions can enable operations to withstand extreme temperatures, abrasive conditions and demanding torque requirements, delivering reliable performance and extended service life in one of industry’s toughest environments.

David Strain is technical director at Technidrive

www.technidrive.co.uk