Intersection 10 Hudson Yards
+34 948 14 56 11



FRENOS ELÉCTRICOS UNIDOS S.A. (FRENELSA) is one of the world’s leading manufacturers of eddy current retarders for dynamometers, commercial vehicles dedicated to the transport of people and goods by road (buses, coaches, trucks, tractors and trailers) and other braking solutions.

We export more than 95% of our production to more than 50 countries on five continents.

Thanks to our experience and Know-How, we offer high-quality products, components and services, always seeking maximum customer satisfaction.

Unlike other brands, we manufacture all the components in our plant, so we have greater control over the manufacturing and assembly of the components and the requested delivery times.


The objective of FRENELSA’s quality policy is to supply products and services to the market that offer maximum customer satisfaction in terms of EFFICIENCY, SAFETY, SERVICE and RELIABILITY, through continuous improvement in all actions.


All FRENELSA staff accept personal responsibility in achieving this objective, and strive to exceed the expectations of our clients through strict compliance with internal procedures and regulations, contributing to improving SAFETY, HEALTH and the ENVIRONMENT.


For all these reasons, we have implemented and apply a quality system in accordance with the requirements of the DIN EN ISO 9001 standard, which is regularly verified by the TÜV CERT entity of Germany.


FRENELSA’s management recognizes that complying with the quality policy as well as current regulations and legislation is a key responsibility for the future, and is also committed to continuously improving the safety and health at work of all employees.

This entire means that today FRENELSA is a synonym of QUALITY.









FRENELSA Retarders - Ralentizadores eléctricos - Frenos eléctricos

Our history


The companies Onecasa, Frenos Iruña and Superfrenos develop, manufacture and market electric retarders.


Foundation of FRENOS ELÉCTRICOS UNIDOS S.A. (FRENELSA) by the merge of the 3 previous companies.


First brake exported.
Opening to the European, American and African markets.


Launch of the first axle with electric retarder for semi-trailers.
The staff is doubled.


Expansion and modernization of the R&D and Quality departments, new test bench and laboratory.
The German subsidiary FRENELSA RETARDER GmbH is created.
Opening of markets in Oceania and Asia.
First obtaining of ISO 9001 quality system certification.


Move due to expansion to new facilities.
Incorporation of new production lines.

2010 years

Opening of the subsidiary FRENELSA MEXICO.
Expansion of machining lines.
Range renewal.

2020 years

Expansion of non-destructive testing facilities.
Power generation for self-consumption.
Digitalization production process.

Our values


All our actions are based on ethical criteria and values in the relationship with all our areas of relationship: clients, suppliers, administration, institutions and society in general.


We are firmly convinced that people are our main asset. We are committed to talent by promoting diversity and equal opportunities.


Both, the products we offer and the production means we use to manufacture them, actively contribute to protect the environment.


We prioritize the health and safety of our employees and collaborators, the reduction of accidents and the continuous improvement of working conditions.


More than 50 years of continuous work and research in the sector guarantee our experience and make FRENELSA present in the markets of the five continents with an export volume of 95% of production.


Frenelsa RDI

Continuous research, innovation, the constant development of our products and diversification are the keys that allow us to be competitive in today’s environment.

The Know-How acquired in our more than 50 years of experience is the fundamental basis of our work.

With our sights set on the future, at FRENELSA we invest significant resources in Research and Development of our products. The use of advanced computer programs in design and simulation together with the most modern testing technology makes it possible for us to be at the forefront of our field.

All of this together with the most modern technology in the manufacture of the components of our products, makes our clients have the peace of mind that the products supplied by FRENELSA are reliable, safe and very profitable.


We take care of the environment

Our products and the way we manufacture them actively contribute to the conservation of the planet.

The FRENELSA retarder reduces the emission of fine particles from friction brakes, minimizing the associated health risks.