This is a rendering of Prototype II of the open source, design-for-disassembly tractor, LifeTrac. You can download the source in Blender format.
This is the reality of the completed frame, with the wheels and wheel motors, minus the PowerCube engine unit.
(download photo shoot in hi res here)
Now hang the 18 horsepower PowerCube I on the rear of the frame, and take it for the first test drive.
LifeTrac II Test Drive from Marcin Jakubowski on Vimeo.
This insane freak purrs like a cat and rips the ground. Major success.We have now demonstrated a workable design with LifeTrac II. Can it be any simpler? We took out the articulated joint that was present in LifeTrac I, since OSE Specifications prioritize simplicity. Skid steering may not be as elegant as articulated steering, but it works just as well. Moreover, a fixed wheel base allows us to mount tracks on the wheels, such that the obtainable traction surpasses that possible with LifeTrac I – which cannot accomodate tracks because of its articulated joint.
The frame is bolted together from 1/4″x4″x4″ mild steel square tubing. A hydraulic motor is mounted on each wheel. Quick-connect hoses run from each motor to the control valve. The PowerCube connects to the control valve with two additional quick-connect hoses.
The flexibility of the design is extraordinary – wheel motors are detachable and have quick couplers. The valve is detachable and has quick couplers. The hoses have quick couplers. This means that all these hydraulic components may be used elsewhere, as part of a flexible Lego set for real technology. Moreover, the quick disconnects allow this tractor to operate in 2 wheel drive and 4 wheel drive.
We know of no other machine in this world which features this level of part interchangeability or modularity. This is a feature that allows one to control equipment costs to the lowest possible – not only by repurposing components, but being able to service or repair the machine readily.
It turns out that 18 horsepower – or a single PowerCube unit – is quite satisfactory for driving this basic tractor. The next step is to build tracks to connect the wheel pair on each side, such that traction is never lost on uneven terrain.
If you would like to build the above tractor, the Blender drawings of 23rd of August, 2010, are exactly what we built as far as the frame above. We may shorten the wheel base if we have problems with skid steering – so this is a consideration for any early adopters out there. This was our price ticket:
This is about a buck fifty per pound of the 2214 lb machine, or about the going price of tomatoes. That is without the PowerCube. If you use an off-shelf 18 hp engine – the price may be $1225 ($500 for 18 hp engine + $200 pump + $225 frame + $300 balance of system). The total is then $4808.
Now we add the front loader:
Heavy duty front loader arm metal (3/8″x3″x6″ rectangular tube) – $500
Cylinders – $600
Control valve – $200
Hoses – $100
Couplers and fittings – $100
Quick Attach plate – $150Cushion valve – $66
TOTAL FRONT LOADER COST – $1716
Now add the rear loader:
Rear Loader Cylinders – $520
Heavy duty rear loader arm metal (3/8″x3″x6″ rectangular tube)- $340
Selector valve (4) – $180
Quick attach plate – $150
Cushion valve – $66
TOTAL REAR LOADER COST – $1256
Overall cost for a dual loader tractor – wheel base of about 7×7 feet, designed to handle 3 Power Cubes, for a power limit up to approximately 150 hp – $6550 without the PowerCubes. Design is absolutely scalable, such that a half-size version – or MicroTrac, may be made – and it can be designed readily from our Blender model drawings.
Now here’s the good part. We aim to develop the induction furnace within 2 years, with which we will be able to produce all tractor structure and components, minus the rubber parts, from scrap steel. This means that we will demonstrated how to build a tractor at the cost of scrap metal plus rubber, plus energy to run the induction furnace. This should be about $1k in materials such as hoses and hydraulic seals, plus labor. This indicates a possibility of closing the industrial divide between the developed and developing worlds.
