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I see tractors with really high wheels and with the carriage placed really high. Similar to this one:

enter image description here

How are the wheels powered? Is there is an electric motor for every wheel powered from diesel generator somewhere in tractor?

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    $\begingroup$ Please insert the picture into your question directly instead of linking to another site. The link my become broken and then the question will lose value. $\endgroup$
    – hazzey
    Mar 7 '18 at 15:33
  • $\begingroup$ @hazzey I do not own the picture. $\endgroup$
    – matousc
    Mar 11 '18 at 18:50
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The wheels are powered by hydraulic motors, one for each wheel.

The pipes for supply and return can be seen on the left side wheels.

Edit: It could be possible to provide an "ugly" (term as used in the comment below) solution with driveshafts, but, since driveshafts either with Hardy-Spicer joints or Constant Velocity joints have a maximum working angle then they would eat into the clearance available under the machine which is necessary for the crop to pass under without damage.

If one did use the driveshaft solution this would increase the height of the machine and, if the wheelbase stays the same, would increase the chances of it falling over when used on sloping terrain - not all countries are blessed with large flat fields...

Why don't they use electric motors? Well, a good guess is that most agricultural mechanics are already well-versed in hydraulics (all the ones I have met and worked with) and are more than capable of sorting most, if not all, hydraulic problems : spool valve blocks, oneway valves, pumps, motors etc. Going to electric would give them a completely new ball game and they would probably avoid purchasing machines and stick with what they know...

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  • $\begingroup$ Can you provide a little info on how a hydraulic motor works, or more to the point, why it's preferred in this case to some ugly concoction of driveshafts, U-joints, and differential? $\endgroup$ Mar 7 '18 at 16:22
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    $\begingroup$ @CarlWitthoft I don't believe that an explanation of the workings of a hydraulic motor is really required by the question as asked. I have made an edit for the driveshaft solution. $\endgroup$
    – Solar Mike
    Mar 7 '18 at 16:46
  • $\begingroup$ Hydraulic motors are generally smaller and lighter compared to electric motors with the same output, and thus cheaper. (Though freight locomotives tend to prefer diesel-electric traction. I guess that has to do with the higher speeds.) $\endgroup$
    – JanKanis
    Jul 2 '18 at 20:43
  • $\begingroup$ Using driveshafts with 90° couplings is also possible without eating into the clearance, but that is probably heavier and more complex than hydraulics. And hydraulics can also replace the gearbox, and perhaps power other machinery on the vehicle. $\endgroup$
    – JanKanis
    Jul 2 '18 at 20:52
  • $\begingroup$ @JanKanis I have not seen many freight locomotives ploughing fields... $\endgroup$
    – Solar Mike
    Jul 2 '18 at 21:12

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