Why are Front Wheels Canted
auerbach
Join Date: Sep 2007 Posts: 2168 West of Toronto Pics |
2008-10-31 157587
Tractors with a tricycle configuration (the two fronts close together) usually have those fronts canted so the tops are apart and the bottoms almost touch together. I assumed that was so there'd be a single front tire mark on the soil, but some equipment like road graders also have the fronts not touching but still canted way over. What's the advantage of that?
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Why are Front Wheels Canted
Murf
Join Date: Dec 1999 Posts: 7249 Toronto Area, Ontario, Canada Pics |
2008-10-31 157588
First off, the tires are canted for two different reasons, so, tractors first.
Those tricycle style tractors (often called 'widow-makers' because of their tendency to roll over on hill-sides or in fast turns) were designed that way so that the tires lined up such that you could drive through a crop with one tire in each of 3 rows, for things like cultivating or harvesting. Usually the 2 back axles were longer than needed and the hubs could be adjusted back & forth to line up perfectly to different row spacing. It was also cheaper to build (and therefore sell) at a time when money was tight.
As for road graders, the ability to can the tire over sideways greatly improves the graders ability to go in a straight line even with a tremendous load on the angled blade wanting to push it over to one side. In the case of the grader, the front wheels have steering in 2 dimensions so you can vary both the vertical aspect of the wheels, and the traditional steering 'on the fly' from the operators station. The tipped wheel itself has a steering effect, kind of like the leaning of a bicycle or motorcycle does.
Best of luck. ....
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Why are Front Wheels Canted
auerbach
Join Date: Sep 2007 Posts: 2168 West of Toronto Pics |
2008-10-31 157590
Thanks! ....
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Why are Front Wheels Canted
earthwrks
Join Date: Dec 2003 Posts: 3853 Home Office in Flat Rock, Michigan Pics |
2008-10-31 157597
The closeness of the front tricycle wheels being close together at the bottom is also a function of design to reduce forces acting on the wheels as one single wheel (also known as bump steer). If the wheels were on just a short axle, say 12" apart, if one wheel were to hit an object or bump steer it could rip the wheel out of your hand and possibly instantly change the steering direction. If you ever built and used a wooden go-cart that had a sraight axle that you used your feet to steer you know what I'm getting at.
On graders, they're called "leaning wheel"--ingenius, eh? The principle behind it is causes the tires to dig in and hold for the most part---as you run the blade forward the force wants to straighten the blade/machine and causes the grader to slide toward the furthest point of the blade--the wheels have to lean the other way to counter the force. For example, if you have ever tried walking up a hill of dirt flat-footed it can be difficult to again traction. But if you dig in the side of your shoes into the hill you go right up.
As far as steering, I'm not sure about being easier to steer. I have a leaning-wheel grader (not all lean, even new ones) and either way it takes a lot of back and forth to get turned around--it's like turning a bus around. My grader has a sliding moldboard (blade) meaning the blade hydraulically slides out about 4 feet which makes having leaning wheels even more necessary as the forces act like a big lever that tends to spin the entire machine around using the tip of the extended blade as a fulcrum. ....
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Why are Front Wheels Canted
hardwood
Join Date: Dec 2002 Posts: 3583 iowa |
2008-10-31 157599
Another reason for the canted front wheels on a farm tractor was to let mud or a stone that got pinched between the tires at their bottom most point of their rotastion to fall out before it got to the steering post between the front wheels.
I and a friend of mine who spent his working lifetime running a county road grader were just discussing grader design a few days ago. He started before thay had hydraulics, then ended up as his last grader an articulated Deere. His comment was that the ability to cant the front wheels always was a big help, but that along with articulating the frame was a joy to operate. ....
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