Mekarski System
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The Mekarski system was a compressed-air
propulsion system Propulsion is the generation of force by any combination of pushing or pulling to modify the translational motion of an object, which is typically a rigid body (or an articulated rigid body) but may also concern a fluid. The term is derived fro ...
for
tram A tram (called a streetcar or trolley in North America) is a rail vehicle that travels on tramway tracks on public urban streets; some include segments on segregated right-of-way. The tramlines or networks operated as public transport are ...
s invented by Louis Mékarski or Louis Mékarsky (the correct spelling is uncertain) in the 1870s. He worked in
France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...
, was born in 1843 in
Clermont-Ferrand Clermont-Ferrand (, ; ; oc, label=Auvergnat (dialect), Auvergnat, Clarmont-Ferrand or Clharmou ; la, Augustonemetum) is a city and Communes of France, commune of France, in the Auvergne-Rhône-Alpes regions of France, region, with a population ...
(center of France) of Polish origin. Many references to him use the
Polish Polish may refer to: * Anything from or related to Poland, a country in Europe * Polish language * Poles, people from Poland or of Polish descent * Polish chicken *Polish brothers (Mark Polish and Michael Polish, born 1970), American twin screenwr ...
name ''Ludwik Mękarski''.


Overview

A problem with compressed-air propulsion is that the air cools as it expands, which can lead to the formation of ice in the power cylinders. Mekarski sought to overcome this problem by heating the air with
steam Steam is a substance containing water in the gas phase, and sometimes also an aerosol of liquid water droplets, or air. This may occur due to evaporation or due to boiling, where heat is applied until water reaches the enthalpy of vaporization ...
, produced in a small
boiler A boiler is a closed vessel in which fluid (generally water) is heated. The fluid does not necessarily boil. The heated or vaporized fluid exits the boiler for use in various processes or heating applications, including water heating, central h ...
called a ''bouillotte''. It is uncertain whether the steam was mixed with the air, or whether there was a
heat exchanger A heat exchanger is a system used to transfer heat between a source and a working fluid. Heat exchangers are used in both cooling and heating processes. The fluids may be separated by a solid wall to prevent mixing or they may be in direct contac ...
. It was a single-stage engine in that air was expanded in one piston and then exhausted. The air was reheated after leaving the tank and before entering the engine. The reheater bubbled air through a hot water tank, picking up hot water vapor to improve the engine's range. An improved engine contained a high-pressure cylinder of 5 inches operating at 50-150 lb/sq.in and a low-pressure cylinder of 8 inches, with an 8-inch piston stroke. The system was promoted as being suitable for use in congested streets and in tunnels, as compressed air produced no smoke or flames, and thus would not disturb horses or fill the carriage with soot and sparks like a steam engine. But the technology had two decisive disadvantages. Firstly, sometimes the stored energy was not sufficient to bring the tram back to the filling station and secondly, the compressed air hoses tended to burst from time to time with great hiss and frighten the tram riders.


Applications

The system was tested in
Paris Paris () is the capital and most populous city of France, with an estimated population of 2,165,423 residents in 2019 in an area of more than 105 km² (41 sq mi), making it the 30th most densely populated city in the world in 2020. S ...
in 1876 and introduced to the tramways of Nantes in 1879. It seems to have been a success at Nantes with a fleet of 94 trams in 1900. The Mekarski tramcars continued in use there until 1917, when they were replaced by electric trams. The system was used in
England England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe b ...
on the
Wantage Tramway The Wantage Tramway Company was a two-mile tramway that carried passengers and freight between the Oxfordshire town of Wantage and Wantage Road Station on the Great Western Main Line in England. Formed in 1873 to link Wantage Road station with ...
but did not find favour there because the compressor plant used more than four times as much
coal Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal is formed when dea ...
as a
steam locomotive A steam locomotive is a locomotive that provides the force to move itself and other vehicles by means of the expansion of steam. It is fuelled by burning combustible material (usually coal, oil or, rarely, wood) to heat water in the locomot ...
. Between 1881 and 1883 an improved air car was used on the Caledonian Road tramway of the London Street Tramway Company. Furthermore, the system was in use in
Bern german: Berner(in)french: Bernois(e) it, bernese , neighboring_municipalities = Bremgarten bei Bern, Frauenkappelen, Ittigen, Kirchlindach, Köniz, Mühleberg, Muri bei Bern, Neuenegg, Ostermundigen, Wohlen bei Bern, Zollikofen , website ...
from 1890 till 1902. There was 3.1 km long line with 10 cars in operation, which went from
Bärengraben The Bärengraben, or Bear Pit, is a tourist attraction in the Swiss capital city of Bern. It is a bear pit, or enclosure housing bears, situated at the eastern edge of the old city of Bern, next to the Nydeggbrücke and the River Aar. Although ...
via
Bern railway station Bern railway station (german: Bahnhof Bern) serves the municipality of Bern, the federal city of Switzerland. Opened progressively between 1858 and 1860, and rebuilt several times since then, it lies on the Olten–Bern and the Lausanne–Bern l ...
to the cemetery. The compressed air was generated by a compressor driven by a water
Jonval turbine The Jonval turbine is a water turbine design invented in France in 1837 and introduced to the United States around 1850 and were widely used. The Jonval turbine is a "mixed-flow" turbine design. Mixed-flow designs were well suited for the low-head ...
with water from the
Aare The Aare () or Aar () is a tributary of the High Rhine and the longest river that both rises and ends entirely within Switzerland. Its total length from its source to its junction with the Rhine comprises about , during which distance it descend ...
. The filling station was at Bärengraben. It was an advantage that the cars on the return trip had to go only downhill, so when they run out of air, they had still the possibility to reach the filling station. Nevertheless, the filling used quite some time. Therefore, four filling connections have been provided, which were used by two to three cars simultaneously. Four cars where on the route service and the rest was in the shed for maintenance and repairs. The operating pressure was 480 psi, the speed was 9.3 mph. Each run consumed about 2100 liters of compressed air.


Preservation

One Mekarski tramcar is preserved at Nantes.


See also

* Diesel-pneumatic locomotive *
Fireless locomotive A fireless locomotive is a type of locomotive which uses reciprocating engines powered from a reservoir of compressed air or steam, which is filled at intervals from an external source. They offer advantages over conventional steam locomotives of ...
*
Pneumatic motor A pneumatic motor (air motor), or compressed air engine, is a type of motor which does mechanical work by expanding compressed air. Pneumatic motors generally convert the compressed air energy to mechanical work through either linear or rotary m ...
*
Tram engine A tram engine is a steam locomotive specially built, or modified, to run on a street, or roadside, tramway track. Legal requirements In the steam locomotive era, tram engines had to comply with certain legal requirements, although these varie ...


Sources

* See external links


External links


Compressed-air motors
The Museum of Retro Technology

Tramway Information * French Wikipedia article
Dampftram Bern
steam and Mekarski trams in Bern today (in German, scroll down page for partial English translation) {{DEFAULTSORT:Mekarski system Pneumatics Tram technology