CHANGING FARM MACHINES O Farm machines have progressed from being pulled by animals to being powered by steam to now being powered by gas and hydraulics Though today's machines are far more efficient than those of the past their creation would never have been possible without the inventions that came before them ANIMAL POWER Before steam engines were invented farm machines such as plows were pulled by animals including horses and cows left Animals are still used on farms in many parts of the world today 12
FOUR WHEEL DRIVE TRACTOR I Some of the most powerful farm tractors have four wheel drive This means that all four wheels are powered by the engine instead of just the back two wheels as in the standard tractor see pages 8 9 Four wheel drive allows the tractor to travel over the muddiest terrain Computer control Inside the driver s cab is a computer that I tells the farmer how the tractor is performing Because the tractor s wheels might slip in the muddy conditions the tractor also uses a radar system that tells the driver the tractor s exact Cleaner engines Today's tractor engines work efficiently saving farmers money on fuel Efficient engines also give off lower levels of harmful exhaust gases helping to keep the environment cleaner Front attachments This tractor also has attachment points on its front This means that a farmer can power and control more than one machine at the same time 140
A This four wheel drive tractor above also has a special suspension system that allows it to drive on roads at speeds of up to 50 miles 80 kilometers per hour nearly twice as fast as other tractors Rear strength The back of this tractor can lift a load of over three tons 2 7 metric tons about the weight of a fully grown elephant Special suspension The rear wheels on most tractors are linked by a solid rear axle that has little or no suspension This means that they cannot absorb bumps in the ground very well so the ride is pretty bumpy All four wheels on this tractor however have independent suspension This reduces the vibration allowing it to drive faster on all surfaces 15
