Imbert was not the first to discover a method of generating wood gas, but he did
design a system which could be practically applied to cars and
lorries. They are under-represented in photographs, no doubt for
propaganda reasons, but a
considerable proportion of the rear echelon vehicles of the German army,
and an even higher proportion of civilian vehicles in occupied Europe
were powered by wood gas generators - Holzgaz to the Germans, Gasogene
to the French.
Matador produces three Imbert kits:
Matador kit KCG-25 depicts a typical Imbert unit as fitted to the Opel Blitz. The Blitz in German yellow is built straight according to the instructions.
The kit depicts the four visible parts - gasifier (burner), gas cooling radiator, piping and water filter. The second, carbon, filter is not seen as it was mounted internally as it nearly always was on lorries.
Photographic evidence shows two positions for the water filter. A little cutting and converting of the unit and the kit chassis enables the front-and-back version seen here on the grey truck. Both versions achieved factory production. There were many minor variations, and the modeller wishing to depict an individual vehicle will need to follow photographs.
The two principal versions of the Holzgas Opel Blitz. This kit could be adapted to fit some other makes of lorry too.
| Note that here the bodies are different.
This reflects photographic evidence. Sometimes the load bed
was cut away behind the burner, and sometimes it continued in
matters is that there was always a wood box, and always a barrier
between the burner and the body - the burner got hot!
Both these versions achieved factory production status.
Photographs show similar units attached to a wide variety of lorries, cars and even some tracked vehicles. Earlier examples, workshop-made, have many minor, and even major variations. This kit may also be used to convert Mercedes lorries.
|The key features of the Imbert system - a
much-repeated and re-drawn diagram, here sourced from http://self-sustained.com/
an excellent source for understanding the system. The chemistry
is simple. Heating the wood with low amounts of oxygen causes it
to reduce to ash and give off gas - a mix of nitrogen, carbon Monoxide,
Carbon Dioxide, Oxygen, Hydrogen and Methane.
This mixture burns well, though the Carbon Monoxide is a slow burning gas. The nitrogen limits the efficiency, and another danger was the fact that the Carbon Monoxide is extremely poisonous.
|The gas also contained tar, particles of ash and sulphur - all of which would do a serious mischief to the engine. The first water filter removes most of the tar and ash particles. Then the radiator cools the gas. Then the second, charcoal, filter removes most of the sulphur. Then a blower delivers the gas to the engine.|
Generator Parts Kit
Any depiction of civilian traffic in occupied Europe should probably include Holzgas/gasogene vehicles, all slightly different, and many made up in workshops, so in some cases very crude in appearance.
How to use this kit: the parts kit is designed to allow a range of typical vehicles to be built. It contains the obvious parts - burners, filter cylinders, radiators, and pipes. There was another typical feature: wood. If a burner-load of wood gave a range of, say, 60 miles, any longer journey meant wood needed to be carried. The typical wood burner had a roof rack, a wood box, a trailer, or just a pile of sacks, or even of loose wood. Using the parts and photographs, assemble to taste, remembering the following points:
Additional parts:the modeller needs to build a guard between the burner and the load bed of any lorry conversion. This varied in height between the same as the side, and up to more than 2 metres. It was vital not to allow sparks to get to the cargo, and if the cargo was something like bales of hay, the barrier had to be higher than the cargo.
Most lorries had a wood box - a simple plank chest to carry fuel. These may be made up from plastic card to fit individual vehicles. Some photos show the whole load bed behind the gasifier, with a wood box next to it - rather as British lorries sometimes had their fuel tank and spare wheel carrier between the cab and the load bed.
Many lorries had some sort of ladder or steps, so that crew could climb up high enough to load or rake the burner.
Crew: typical maintenance poses might include: standing over the burner stirring downwards with a pole to clear any wood or ash blockages; pouring wood from a sack into the top of the burner; turning one of the circular hatches on the burner or filters - clearing ash or cleaning/ draining the filters.
On the Eastern Front, the woodburners had an extra use during the brutally cold winter weather. A hose was run from the vehicle, attached just before the gas would normally enter then engine. It looked not unlike an exhaust pipe - and in this scale could easily be made from one, with a cylinder like the silencer. At the end was a cone- or pistol-shaped nozzle. The gas was lit, and the hot air generated used to warm the engine of the host vehicle or others round it.
The idea of this kit is to enable the modeller to build typical examples of the unlovely fleet of converted vehicles. To taste, specific examples may be found from photographs, or generic vehicles built. There is a wealth of possibilities, including many of the older and newer lorries available, cars, and captured vehicles - including Fords, Chevrolets and Bedfords. Matador kits for which we have seen Holzgas conversions include:
Others in the range- such as the covered cars, the Matford, MAN E300 and Fiat 626 trucks are probables but we have yet to see it proven.
Matador's third Imbert kit converts any 76th scale Kubelwagen. The Airfix and Fujimi kits are so similar in dimensions and design that parts are virtually interchangeable. A good 72nd kit should be dimensionally so simiar that it could be converted. The burner was placed in the front - the vehicle being rear-engined - and one of the filters was visible as it was placed across the vehicle. This also achieved factory production status, though surviving photographs show significant differences between examples. Interestingly, one of the few surviving pictures of a Kubelwagen with truck body (Matador KCG-19) is of an Imbert version.
|The gasogene/Holzgas conversion kept many vehicles running through the war. It was particularly useful for big heavy vehicles such as buses and lorries, and also for tractors. The vehicles were difficult to drive, as the driver had to monitor the gas supply, and the lack of range and high maintenance made them much less convenient. After the war, as soon as petrol was available, the vehicles were either scrapped or converted back.|