A vehicle gasifier system with its fuel adds about 175-315 kg to a vehicle by the carrier’s own parts list, and 50-80 kg of wood chunks fills roughly 0.143-0.32 m³ of hopper, more than a 200-litre drum in the worst case. That load also moves the axle weights: a 250 kg unit mounted 1.0 m behind the rear axle of a 3.0 m wheelbase adds 333 kg to the rear axle and takes 83 kg off the front one.
Part of Vehicle Gasifier Design
The weight and volume a gasifier system, its cleaning train and its fuel add to a vehicle, and how that load shifts the vehicle’s axle weights.
What The System Weighs
The carrier lists the parts as: reactor 50-100 kg, cyclone 15-25, cooler 20-40, filter 10-20, piping, frame and hopper 30-50, and a fuel load of 50-80 kg of wood chunks.
- Parts without fuel: 50 + 15 + 20 + 10 + 30 = 125 kg to 100 + 25 + 40 + 20 + 50 = 235 kg.
- With fuel: 125 + 50 = 175 kg to 235 + 80 = 315 kg.
- The carrier gives 150-300 kg “including” the fuel, which does not match its own list at either end. This page uses the list.
A van with a 1,000 kg payload gives up 175 ÷ 1,000 = 17.5% to 315 ÷ 1,000 = 31.5% of it. A small car with a 400 kg payload may not have room for the load at all, which is the reason the carrier prefers trucks and vans.
What The Fuel Takes In Volume
Wood chunks of 3-5 cm pack at a bulk density of about 250-350 kg/m³ (an assumption; fill a bucket and weigh it).
- 50 kg at 350 kg/m³: 0.143 m³ = 143 litres.
- 80 kg at 250 kg/m³: 0.32 m³ = 320 litres.
- A 200-litre drum holds about 50-70 kg of that fuel.
The hopper therefore cannot be the narrow firetube: a 30 cm tube of area 0.0707 m² would need to be 2.0-4.5 m tall to hold 0.143-0.32 m³. The hopper is a wider vessel above the reactor, or the unit carries a separate fuel bin and is topped up by hand. The carrier’s “refuel every 30-45 minutes” shows how often that bin is expected to run down, and carrying the fuel is covered in Fuel Preparation & Carrying.
Where The Weight Goes On The Axles
Treat the vehicle as a beam of wheelbase L supported at the axles. A load W placed a distance x behind the rear axle adds W × (1 + x/L) to the rear axle and removes W × x/L from the front.
- W = 250 kg, x = 1.0 m behind the rear axle, L = 3.0 m: rear +250 × (1 + 0.333) = +333 kg; front −250 × 0.333 = −83 kg.
- Moved to 0.5 m in front of the rear axle (x = −0.5 m): rear +250 × (1 − 0.167) = +208 kg; front +42 kg.
Rear-mounting on a car shifts weight off the front wheels, which lightens steering and braking at the front, matching the carrier’s warning that a rear-heavy car handles badly. A load centred near the rear axle, or ahead of it on a truck, is better. Check the result against the axle ratings of the vehicle you have.
What You Need
- The vehicle’s payload and axle ratings, from its plate or its manual.
- A scale, or at least weighed parts, before committing to a mounting position.
- A plan for the fuel bin, since its volume is larger than it looks.
Common Mistakes
- Forgetting the fuel. It is 50-80 kg and changes through the day.
- Hanging the unit far behind the rear axle. It lightens the front wheels.
- Sizing the hopper from the firetube diameter. The volume does not fit.
Safety
Weight changes braking, and the load carries carbon monoxide
A heavy unit overhanging the rear lengthens braking distance and lightens the steering. The unit holds a fire and gas that is about 18-22% carbon monoxide by volume; never start, warm or park it in a garage or shed, and do not sleep in the cab beside a lit unit. A gasifier that breaks loose at speed is catastrophic, so fix it at several points. See Carbon Monoxide Risks.
What’s Next
- Learn next: Material Selection for Mobile Use — lighter materials where heat allows
- Combine with: Vehicle Mounting — where the load goes