LPG tractors by John Deere - farming with gas
The aforementioned two were just a minor part of a broad range of LPG-powered John Deere tractors. Practically all models equipped with spark-ignited engines (fueled with petrol, but also other liquid fuels) were offered as LPG-fueled counterparts.
The 620 LP, manufactured in the 1950's, is one example. It was powered by a 5-litre, 2-cylinder spark-ignited engine (bore and stroke – 140 x 162 mm, respectively). The LPG version's compression ratio was 8,1:1, whereas the multifuel version's was as low as 4,78:1, which allowed to fuel the engine with pretty much any combustible liquid. The propane variant of the motor had a whopping 44 PS of power and the tractor's LPG tank was capable of holding 125 l of „juice”. Power was transmitted to the rear axle through a 6-speed, non-synchromesh gearbox.
The 3020 is yet another instance. While it remained in production until 1972, the LPG version was manufactured until 1969. It had a 3,7-litre, 4-cylinder engine (bore and stroke – 108 x 102 mm, respectively), churning out 65 PS at 2500 RPM. The transmission was fully synchronised and offered 8 gears plus 2 reverse ones.
In the 1970's, Diesel engines took over and LPG was gradually phased out as a fuel for farm tractors. Today, with the advent of diesel-gas technology, it is poised to return and in fact it is returning in some parts of the world, including Poland. Blending diesel and LPG results in boosting engine performance, cutting down emissions and slashing fuel bills, so in all probability we will see propane used in tractors again in the not-so-remote future.