First a bit of history: Monroe developed the first automotive shock absorbers – in 1924. This company started life in the USA, state of Michigan and the village of Monroe. After starting with tyre pumps, the company soon moved onto the manufacture of shock absorbers (originally called the Monroe Shock Eliminator). Although the word “damper” is a better description of what is happening, we seem to have embraced the term “shock absorber”. This was in 1926 and was followed by a double action mechanism in 1929 and haven’t looked back since. Effectively, the energy from bumps is transferred to energy in the springs and the dampers convert this into heat by moving oil through chambers via small orifices.
1980 saw the more advanced manufacturing of McPherson struts. In 1989 the Armstrong Shock Absorber company was bought out. The company has had many acquisitions and changes over the years and now has manufacturing facilities in over 20 countries in addition to 14 engineering centres on five continents. We visited the St. Truiden Monroe factory in Brussels where we also met up with the European leg of the roadshow “Tenneco on Tour” housed in two semi-trailers and an inflatable marquee tent. The objective was to create awareness of some of the major products that Tenneco supplies to most of the automobile manufacturers around the globe as original equipment as well as aftermarket. Although Tenneco’s list of O.E. and aftermarket products is long, the two main lines are Monroe Ride Control and Walker Emission Control.
Another of Monroe’s designs is Acceleration Sensitive Damping (ASD) using mechanical valves that adjust according to the road forces. In 2007 Monroe developed CES or continuously controlled electronic suspension together with Ohlins Racing using an electronic controller and chassis sensors. Tenneco also bought out Italian Marzocchi forks and struts mainly supplying the motorcycle and mountain bike markets.
When McLaren needed a special suspension for their MP4-12C Monroe developed a system that does away with the need for anti-roll bars. Instead, the four corners are linked by hydraulic piping linked to an electronic control unit to provide fully adjustable suspension that compensates for different road conditions as well as hard cornering. Top-end manufacturers will be using this system in increased numbers in the future.
The other large part of Tenneco’s business is Walker Exhaust systems. An interesting display of the evolution of Walker exhaust systems shows just how advanced and complex things have become over just a couple of decades. Kicking off with a straightforward exhaust pipe from front to back interspersed with two or three mufflers, the emphasis then changed from mere noise reduction to emission control. So catalytic convertors were added, then oxygen sensors (lambda sensors) plus all the electronics involved. For diesels, this was followed by the addition of diesel particulate filters and finally we have Ad Blue. This doesn’t stop at dual catalytic convertors and a diesel particulate filter in the exhaust system:- it adds another injector that takes care of the remaining NOx gases by injecting a Aqueous Urea solution called Ad Blue. This reduces the final NOx gases to N2 and H2O (nitogen and water). Complex, but necessary in order to meet increasinglt stringent emmision control legislation dictated by Euro 4 (2004), Euro 5 (2009) and the upcomming Euro 6 in 2014.
For the full list of Tenneco companies see below: