A diesel-gas farm tractor

© Automax Piotr ChojnackiTThe performance of a Diesel engine running in part on LPG was tested on an Ursus 1234 tractor

The first feasibility studies involved modified 2^nd generation autogas systems fitted to Ursus C-360 and 1234 type tractors. Tests proved successful, encouraging the company to use a dedicated diesel-gas system (Solaris Diesel by Car-Gaz) to convert a contemporary Zetor Proxima vehicle.

The gas injection system comprises a Zavoli S reducer and Hana LPG injectors (colour-coded green for efficiency). The tractor has a tachometer, so providing an RPM signal – which is essential for an LPG system on a self-ignited engine – is not a problem at all. For older engines, not equipped with tachometers, AC generator signal is used instead.

The Zetor has been fitted with a 50-litre cylindrical LPG tank placed between the front axle and the deadweights on the first overhang. Before the conversion, the tractor's fuel economy was 6 l of diesel per working hour, now it is 3 l of diesel plus 4 l of LPG. The result was achieved under stable load, typical of regular field work. When used for transport purposes, characterised by frequent acceleration and braking, the tractor consumes 4,5 l of diesel and 2 l of LPG per hour.

Providing financial savings is just one major advantage of converting a diesel tractor to partially run on autogas, the other being engine performance boosting. Unfortunately, it seems that most tractors purchased by Polish farmers are not powerful enough, which is a result of strict subsidy criteria specified by the Agency for Restructuring and Modernisation of Agriculture. Gaining extra power and torque by fitting an autogas system helps overcome this problem and make field work easier and more efficient with more hauling potential available on demand.

© Automax Piotr ChojnackiThe Zetor Proxima converted to LPG power

Other benefits include reduced noise pollution and less smoke from the exhaust pipe. The latter, however, refers to older vehicles rather than the Zetor tractor. Also, interestingly enough, fumes coming from a diesel engine converted to run in part on LPG are cooler than those emitted by regular diesel counterparts. The difference may be as high as 20° C, which means temperature drops from 280 to 260° C, as measured under load with a temperature sensor placed in the turbocharger.

The Automax Piotr Chojnacki's achievement was noticed and appreciated during the Rol-Szansa 2012 fair in Piotrkow Trybunalski. The company was awarded the Grand Prix in the fair's contest (in the Technical Devices category) and the Lodz province Marshal's cup. It was also nominated for the nation-wide "Key to Success” contest, held under the patronage of Poland's president Bronislaw Komorowski.