Mr D Clare
Harper Adams Engineering Dept
3. Electric Drive 5
4. Efficiency 7
5. Variable Frequency Drive (VFD) 8
6. Infinitely variable (CNH) gearbox 9
7. Emissions 9
8. Electric Vehicle Battery (EVB) 10
9. Hydrogen fuel cell 10
10. Conclusion 11
11. References 12
1. Table1 – advantages/disadvantages 6
1. Fig1. Hydrogen Powered NH2 Electrical Tractor 1
2. Fig2. CASE IH CVX 160 preparing silage pit 2
3. Fig3. VFD Graphs 8
This report investigates the advantages and disadvantages of electrical drives for agricultural tractors. It explains the idea that an electrical driven tractor is currently sufficient in agriculture, compared to the conventional diesel and hydraulic operations. It concludes that, one of the main difficulties with designing an electromotive tractor is maintaining the electrical power. Tractors and machinery often work long hours undertaking such work as harvesting or ploughing. As a result the engine would encounter many tasks, such as PTO operation, hydraulic lifting and high engine torque (ft-lb). The difficulty with current batteries is to be able to provide the necessary electrical power before the need to recharge. The ideas and solutions for such problems are discussed, for example a hydrogen fuel cell electric tractor (as seen in Fig1).
The mechanisation of farming is considered to have begun with the 18th century invention of Jethro Tull’s mechanical seed drill of 1701 (Carroll, 1999). Since then, development has been extensive, for example the leap from steam to gasoline engines. From 1876 CASE manufactured in excess of 35,000 steam engines before shifting its entire production to gasoline tractors during 1920s (Carroll, 1999). In just half a century, engines progressed from a heat engine that performs mechanical work using steam, to an engine in which the combustion of fuel and oxidizer (usually air) is used.
Nowadays, a particular interest of development is revolutionizing eco-friendly methods of propulsion. Emissions regulations and fuel saving are the main reasons for the move. Engine makers have to make further efforts to reduce particulate matter and nitrous oxides coming out of exhaust gas, as well as cutting fuel use. Electrically powered implements offer a good way of achieving that (Cousins, 2012).
Some companies are now demonstrating interest in electrically powered implements. One Swiss tractor maker, Rigitrac, has now started developing a fully diesel-electric tractor. The traditional method of using a PTO shaft and hydraulic oil to transmit power to an implement, is about to be seriously contested by electric motors and cables.
There are various ways of storing the electrical energy, such as batteries (EVB). These are discussed...