History - from control technology to filter technology

Two names

Two names are important when it comes to the foundation in 1949 of the RT Filtertechnik company:

Qualified engineer Wilhelm Binder, development engineer at Binder Magnets in Villingen and qualified engineer Friedrich Landwehr.                                                                                                                    The first person was responsible for the idea, and the second one for its implementation.

Friedrich Landwehr
Altes Gebäude Seemoser Horn

Difficult start

The founder years were characterised by circumstances resulting from the war. It was very difficult to find a room or even only land for a new company. The city of Friedrichshafen on Lake Constance offered some land with a destroyed building directly next to the totally bombed-out Dornier premises.

In spite of an annual rent of DM 1500 and no support from the city council during the provisional setup, the first head office was built here. The first months were characterised by the procurement of material, the provision of financial funds, the organisation of living space, and compliance with the regulations of the trade and industrial inspectorate. At the end of 1948, 3 persons were employed for clearing the ruins, even through the actual company had not yet been founded. Production needed to start to be able to cope with the expenses. In the spring of 1949, an application was made to found a company for the production of electrical devices. In June 1949, the Federal Department of Trade and Industry of the Federal State of Württemberg-Hohenzollern issued the approval to found the company: Regeltechnik Friedrichshafen Dipl.-Ing. Friedrich Landwehr.

Electrical devices

Operations were started with the production of coils. Wilhelm Binder was one of the most important persons of this time. He had the technical knowledge, information on raw materials and business knowledge of the market and customer information.

There were many start-up problems in 1949 until the end of the year. Money was required for wages, rental costs, extension or for purchasing raw materials and initial products, such as insulated copper wire, on the one hand. On the other hand, there were not enough incoming orders or only very small orders.



Hydraulic start: magnetic filter

In this state of emergency at the end of 1949, Professor Dr. Ing. Hans Thoma, the father-in-law of Friedrich Landwehr, already known worldwide in the field of hydraulics, visited the new company in Friedrichshafen together with Mr Binder. Together they laid the foundation for the current field of activities.

Prof. Dr. Thoma
MFK Filtergehäuse

Magnetic filter - hydraulic filter

Prof. Hans Thoma developed the first magnetic filters already in 1930 and filed a patent in 1943. After the war, he continued this development in Switzerland. Prof. Thoma passed his entire knowledge on to the company and ensured every possible support for the future. It soon became clear, as revealed in a letter from Friedrich Landwehr to Prof. Hans Thoma "that something can be achieved with filters and that is a question of survival for"

In the summer of 1950, the first sample filters were provided to companies for testing. The response was very good. From autumn 1950 to spring 1951, this was reflected by letters of recommendation due to excellence from well-known companies such as the machine factory Meer in Mönchengladbach, the Heller brothers in Nürtingen, the machine factory of the Jahn Regulators company in Offenbach am Main or the Ludw. Von Rollschen ironwork company in Switzerland.

This boom was secured by the take-over of the sales of magnet filters in 1952 by Dr.-Ing. Erich Dinglinger AG Filtertechnik in Bremen. This connection in particular soon resulted in many ships being equipped with lubrication oil and fuel filters from the Regeltechnik company in Friedrichshafen. In addition, the magnetic filters were used for a wide range of different tasks: in hydraulic oil circuits or for filtering grinding water; magnetic plugs were developed and sold for almost all German car types. Manual magnetic tools were added to the range of products. Coils and transformers still belonged to the scope of functions.

In spite of all positive developments, there were still problems. The ruined building posed a particular problem. In July 1954, the trade and industrial inspectorate threatened to shut down the company within 14 days if the conditions were not improved and basic safety standards implemented in the factory.



Growth starts

Fortunately, these requirements were only announced, but not implemented. In 1955 the ruined building was overhauled completely. However, very soon, this building also became too small.

A new building was required. In 1964, the company moved into the newly built factory in Buchholz 4, Friedrichshafen. That created the basis for the subsequent, continuous development up until the end of the eighties.

During this time, the company had become well-known for its product quality. The focus was then increasingly on customer-specific filtration problems.  

Success in particular in the field of mobile hydraulics showed that the company had the potential to provide successful solutions in this difficult area: expertise, individual customer support and the best advisory service became the basis for this success and further growth.

Neues Gebäude Seemoser Horn

Building in Berg

Profile in hydraulics

Today, the company can boast longstanding relationships with its customers. One example is the company Dr.-Ing. Erich Dinglinger Filtertechnik in Bremen (today: Polo Filter), with which there is a successful partnership today. Or the Liebherr group of companies, which was gained as a customer 1960 and is the most important business partner of RT-Filtertechnik GmbH today.

In particular, intensive field experience in the mobile hydraulics sector is the basis for expertise on the market.

Successor generation

The retirement of the company founder, Dipl.-Ing. Friedrich Landwehr, resulted in the transformation of the company to REGELTECHNIK FRIEDRICHSHAFEN GMBH in 1990. At this point, his son, Dr. Gundolf Landwehr, entered the company. That ensured continuity and laid the foundation for further developments.

At the end of 1992, the company established a subsidiary company in Kromsdorf near Weimar, which is specialised exclusively in filter elements. At the same time, other important decisions were made for the future. Within 10 years, the number of trained specialists has doubled and the number of qualified engineers has quadrupled. The number of employees has increased significantly.

The company celebrated its 50th anniversary in June 1999. This opportunity was used to show the market, but in particular the customer that the company is concentrating even more on its core capabilities of filter technology. The company's name was changed to RT-Filtertechnik GmbH. The new company image is also for revealing this emphasis on filter technology.

FTW company building

Air photograph of the building in Berg

The long-planned, age-caused generation change in that year provided options for increasing the expertise within the company with best-trained, new employees and for giving the employees even more motivation. The sole managing partner at this time was Dr. Gundolf Landwehr. Together with him, a management team was responsible for sales, customer service, research & development, production and materials management. The sole focus was on filter systems, oil maintenance and filter elements. Dr. Gundolf Landwehr retired in 2009.

Dynamic multi-pass test bench

Tank optimisation test facility

Expansion of the test facility in Kromsdorf

The laboratory area has gradually been increased in size. In addition to further basic analyses, customer-specific development work is carried out in particular, e.g. on oil tanks. A dynamic multi-pass test bench was put into operation in 2008 with 800 l/min, one of the most powerful in the world. That made it possible to practically simulate the pressure curves in hydraulic systems derived from measurements.




Since 2011, a team is preparing the set up and expansion of a new product area for cab-air filtration. Systems are available for retrofitting and also for integration into driver cabs. In addition, a unique test bench was set up for examining complete cabs at the location in Friedrichshafen.

Unique cab test bench

20 years of the Kromsdorf plant

The increase in turnover over the past years has been achieved with new ultrasonic machines, saws and bonding machines. To optimise technological options, a new production shop with an area of 900 m² was built in the anniversary year, 2012.

New filter assembly

Small filter assembly production expansion in Friedrichshafen

The production capacities were also expanded at the location in Friedrichshafen in 2013 for the assembly of pressure and return line filters. Filter systems are assembled here in two-shift operation today.


The primary objective and company philosophy is still to solve the customer's filtration problems with ideally adapted systems. In addition to the company's significant presence in mobile hydraulics, activities have been increased within the complete field of hydraulics and cooperation with customers has been further intensified. Special emphasis is placed on the further development of the filter elements. An increase in performance due to an improved integration of filters in the customer systems is increasingly desired.

The further expansion of customer-specific oil maintenance concepts with attractive service provision offers for oil analyses belongs to our objectives for the future, as well as the active and innovative organisation of the filter market.