Talk:Wheel and axle

Edit 18 June 2007

I removed the example of a wheel turning on a dead axle, because that is not a simple machine. Also removed the picture for the same reason. I will find a suitable picture in due course, if no-one beats me to it.

Not having much luck. There are a few pictures on the net of large wheel and axle mechanisms in the roofs of cathedrals that were used to lift the stones, they would be excellent examples if we could get one of those. Particularly because the wheel looks like a wheel, where most windlasses have a simple handle. Jimbowley 13:24, 6 November 2007 (UTC)

Finally found and uploaded a suitable uncopyrighted picture. Jimbowley (talk) 22:14, 9 May 2008 (UTC)

Wheel and axle

I would like to make some minor revisions to this article. It seems the basic definition of a wheel and axle as a simple machine comes from its use in lifting machines to provide leverage to wind up ropes. While this is technically the source of the term, many also refer to gears as wheels and axle simple machines, while at the same time not calling wheels alone simple machines. I believe this is the problem with applying a Renaissance categorization scheme to modern machines. I recommend simply presenting wheels and their axles in various configurations as the fundamental machine elements that they are. It is historically correct to consider the wheel fixed to an axle that rotates in fixed bearings as a simple machine, but it is awkward and unnecessary to consider a wheel that rotates on bearings mounted on a fixed axle as a different and unrelated device. Prof McCarthy (talk) 06:06, 10 December 2011 (UTC)

I hope these revisions to the article on the wheel and axle are acceptable. I tried to respect the historical context of the simple machine, and keep it simple for elementary school students, while maintaining the spirit of modern machine theory. Prof McCarthy (talk) 16:33, 11 December 2011 (UTC)

I have the opposite view. I think understanding the difference between a 'wheel' and a 'wheel and axle' is important. And this article is about the simple machine not about wheels on axles. After all, a wheel on an axle is just a wheel, and there is a article for that. Jimbowley (talk) 12:23, 4 May 2012 (UTC)

In order to operate as a wheel, it must be able to rotate and what it rotates around is known as an axle. Whether the axle is attached to the wheel and rotates with it in a bearing or the axle is fixed and supports the bearing so the wheel can rotate is not a significant difference. The forces in the system are the same, as are its uses. Prof McCarthy (talk) 11:51, 25 May 2012 (UTC)

I agree with Jim that this article's scope should be kept more limited, to the simple machine. But it would make sense to also include a section that discusses the relationship to the wheel and maybe to other articles that are more appropriate contexts for the wider topic. Dicklyon (talk) 01:24, 26 May 2012 (UTC)

I believe that we are in agreement about the scope of this article, the question is only how the wheel and axle that is a simple machine is related to the wheel. As I have said, they are the same thing. But Jimbowley asserts that the difference is important. As a reminder of how we got here, our colleague prefers that the following paragraphs be removed from this article:

The earliest well-dated depiction of a wheeled vehicle (a wagon—four wheels, two axles) is on the Bronocice pot, a ca. 3500–3350 BC clay pot excavated in a Funnelbeaker culture settlement in southern Poland.

The oldest known example of a wooden wheel and its axle was found in 2003 at the Ljubljana Marshes some 20 km south of Ljubljana, the capital of Slovenia. According to radiocarbon dating, it is between 5,100 and 5,350 years old. The wheel was made of ash and oak and had a radius of 70 cm and the axle is 120 cm long and made of oak.

And I disagree. Prof McCarthy (talk) 04:19, 26 May 2012 (UTC)

Even if we disagree on whether wheel and wheel and axle are substantially different. Wouldn't you agree that pictures of wagons on old pots is not relevant to this article? Jimbowley (talk) 19:01, 9 July 2012 (UTC)

References

Question

I see 2 categories: 'just a wheel' and 'wheel and axle'. From a mechanics view the wheel and axle is a force or velocity multiplier, or it turns a torque into a force, or vice versa. It is a machine and you can use it to increase your effort. Whereas a wheel is just a friction reducing device, you cannot do work with it. Undriven roadwheels are just wheels, but driven roadwheels are both categories because they are doing 2 functions at the same time which can confuse. And the gears in the gearbox are examples of wheel and axle, except for idler gears which are simply components of a machine but not machines themselves.Jimbowley (talk) 22:24, 8 July 2012 (UTC)

ProfMcCarthy, Do you agree with my argument on simple machines:talk that a wheel on a bearing is not a machine? Jimbowley (talk) 22:24, 8 July 2012 (UTC)

In my opinion this is a question that shows you misunderstand the purpose of encyclopedias like Wikipedia. Encyclopedias are not one thing per article, they're one topic per article. A topic is as wide or narrow as you wish. The idea that it's a good idea to explain the very narrow difference between a wheel and wheel and an axle across two different articles is a very poor one. Encyclopedias don't grind up knowledge into teeny, tiny crumbs and put each crumb on one page, readers don't want crumbs of knowledge, so in encyclopedias you put the crumbs together so you can see the context and the interrelationships between the crumbs.

When topics are very closely related like this you're supposed to merge them into one article and accurately and comprehensively discuss them both there, making clear any distinctions. It actually makes things a lot clearer for everyone, including other editors. You also end up with a lot less edit warring.

While there may be a difference, that difference shouldn't be expressed across different articles, it needs to be expressed within a single article.GliderMaven (talk) 00:02, 9 July 2012 (UTC)

If I persuade everyone that the two things are not slightly different, but totally different, would you change your view? 92.236.80.244 (talk) 13:44, 9 July 2012 (UTC)

No, not really. If people go to a page that covers both wheels, and wheels and axles, and they come away understanding any difference there may be, that's actually really good. But here they cannot be totally different, since they both involve wheels, so there's clearly a huge overlap, you know, we're not talking about wheels versus spoons here.GliderMaven (talk) 17:19, 9 July 2012 (UTC)

Sorry but you've just said that if I persuaded everyone they were totally different, you would still think they should share a page, because they are not totally different. I cannot win against such non-logic therefore I won't try. Jimbowley (talk) 17:46, 9 July 2012 (UTC)

I agree with GliderMaven. Let me take a moment to address the specific point Jimbowley makes: "Whereas a wheel is just a friction reducing device, you cannot do work with it." The purpose of a wheel is to amplify the friction force at the road wheel interface to overcome friction at the wheel axle interface. This basic principle of operation is why dragging a cart on wheels requires less force than dragging a load along the ground. The claim that there is a difference between 'just a wheel' and 'wheel and axle' is simply incorrect. Prof McCarthy (talk) 04:23, 9 July 2012 (UTC)

The 'purpose' of a wheel is to make it easier to push your load along the road. It does this by giving you a lower frictional force at the road. And as in your analysis the smaller the axle the smaller the frictional force at the road. This I would call a friction reducing device.

Your statement of purpose above makes no sense... "The purpose of a wheel and axle is to overcome their own internal friction" !! If so, what is the purpose of a frictionless wheel and axle? Jimbowley (talk) 17:23, 9 July 2012 (UTC)

I think the defining attribute of a 'wheel and axle' is that the axle transmits torque (this doesn't include having a little bit of torque present due to friction). Which is not the case for wheels on a wagon, even when the wheels are solidly attached to the axle. Jimbowley (talk) 13:58, 9 July 2012 (UTC)

You seem to be saying that a wheel cannot do work unless it's driven on an axle. So brakes or hub motors don't do work? Wheels are not just friction reducing devices.GliderMaven (talk) 17:19, 9 July 2012 (UTC)

X requires a driven axle to do work, does not imply everything needs a driven axle to do work.Jimbowley (talk) 17:46, 9 July 2012 (UTC)

Note: I will take my 'wheel is not a machine' argument to your machine:talk page, and leave this page just for wheel is not a wheel and axle.Jimbowley (talk) 16:07, 9 July 2012 (UTC)

Friction force does not become less by making the axle smaller any more than friction force on a skid becomes less by making the contact area smaller. To a reasonable approximation the friction force on the axle is equal to the friction force of the load against the ground. What makes the load movable is the leverage of the pulling force at the contact patch of the wheel on the ground, which magnifies this force enough to overcome the friction in the axle. This is the same for a wheel that is attached to a bearing and mounted on an axle, and for a wheel that is rigidly attached to an axle which is then mounted in a bearing. There is no difference. Prof McCarthy (talk) 08:39, 10 July 2012 (UTC)

I said friction force at the road. ( There is no need to keep telling me what the forces are. I realise that most people don't realise that a wheel still works without a reduction in co-efficient of friction. That's the main reasion I added the mechanics and function section to the article.)Jimbowley (talk) 11:09, 10 July 2012 (UTC)

I see what you are saying. You are saying that the wheel is a lever for overcoming the friction at the bearing surface. To me that is a perverse way of looking at it. And it does not correspond to the how we think about all the other machines.

With other machines we look at things like input force, output force, useful work done, efficiency. Friction is often ignored (we call that a perfect machine) but if it is included then it reduces efficiency, etc etc. But when we look at the wheel there is no useful work, and when friction approaches zero it ceases to be a machine!

This is why you can't answer my question about frictionless bearings. If a wheel is a machine because it is a lever to overcome its own internal friction, then what is a wheel with frictionless bearings?

This is becoming philosphical rather than a mechanics questions. Maybe the wheel is a superposition of Machine and NotMachine, where Machine tends to zero as bearing friction tends to zero. Then I'd say we are both right but I'm more right for modern wheels, and you might be more right for primitive wheels. Jimbowley (talk) 11:09, 10 July 2012 (UTC)

Back to this page ('wheel and axle'). Do you not agree that the essence of the 'wheel and axle' is that it transmits (optionally multiplies) forces or torques via an axle (which carries a torque)Jimbowley (talk) 10:01, 10 July 2012 (UTC)

A wheel and axle multiplies forces or torques in exactly the same way as the wheel alone. I do not understand the question of frictionless bearings, because if there is no friction at the contact patch and no friction at the bearings then the movement of the wheel is independent of the movement of the cart. If you are saying there is friction at the contact patch and no friction at the bearing then there is no resistance to a force pushing the cart. In either case it is a machine. Prof McCarthy (talk) 12:41, 10 July 2012 (UTC)

Let's look at pulling a cart, with frictionless bearings on its wheels, and a friction brake acting on the external wheel rim that is slightly locked on. Is the wheel acting as a machine in that example? Jimbowley (talk) 13:13, 10 July 2012 (UTC)

Do you acknowledge that there is something 'different' about how in most machine analysis friction tending to zero gives a perfect machine, but with your wheel analysis the bearing friction tending to zero destroys your definiton of why it is a machine? Jimbowley (talk) 13:13, 10 July 2012 (UTC)

This discussion is getting increasingly bizarre, and I'm looking at you, Jimbowley. A wheel and axle is a simple machine, not an ideal machine. The simple machines are not frictionless.GliderMaven (talk) 13:34, 10 July 2012 (UTC)

I didn't say wheel and axle was an ideal machine, or that it was frictionless. If you don't mind I would prefer to try to convince ProfMcCarthy than you, because that will both have greater benefit and is more likely in my opnion.Jimbowley (talk) 13:48, 10 July 2012 (UTC)

The thing is that in accordance with the theory by Franz Reuleaux what really matters is the hinge/bearing which constrains the motion, not the precise shape of the rotating part. So a wheel with a bearing running on a dead axle and a wheel/axle part that has the bearing on the outside of the axle behave exactly the same (provided the diameter of the bearings are the same).GliderMaven (talk) 14:01, 10 July 2012 (UTC)

In other the words the concept of a wheel/axle isn't simply that of a Renaissance simple machine, in the modern world.GliderMaven (talk) 14:01, 10 July 2012 (UTC)

Correct this is not about where the bearing is. It's about whether the axle is driven.Jimbowley (talk) 14:18, 10 July 2012 (UTC)

Kinematic argument for wheel not a wheel and axle

If you were modelling a complex machine, the wheel could be modelled by just a sliding joint. But to model a 'wheel and axle' you would need a rotating joint and some arms (may not be perfect wording but I'm sure you get my meaning).

A sliding joint is fundametally different to a rotating joint.

Which leads to the conclusion that a wheel is fundamentally different to a wheel and axle. Jimbowley (talk) 14:43, 10 July 2012 (UTC)

When is a machine not a machine

I might be digging a hole for myself, but I think this will help clarify things.

My concept of machine includes useful work out. So if we take a windlass as in the main diagram, and remove the bucket, I could stand there all day turning the wheel. I would be doing work to overcome the friction in the bearing but there is no useful work output.

My view would be that you couldn't do a mathematical analysis of it as a machine. And that it is not acting as a machine in that situation.

ProfMcCarthy, I assume, would see my leverage over the bearing resistance and say that it is a machine. Jimbowley (talk) 17:28, 10 July 2012 (UTC)

I found the American Heritage definition of machines to be helpful. Here is that definition:

<snipped copy paste of definition: jimbowley>

Prof McCarthy (talk) 02:10, 11 July 2012 (UTC)

I'm not sure if this reply is your answer to all my arguments, or just this section. You said you didn't get my frictionless bearing question, so I clarified it and am now awaiting your reply. Over on the machine:talk page you quoted the above definiton for machine, and I'm still waiting for your response (over there please) to my follow up.

I knew I shouldn't have put this section in, the question was sort of philosophical: "If a machine is something that does work, is it still a machine when it is doing no work". I'm not going to take this particular argument any further on this page as it fits better on the machine page, and is a distraction on this page. (and because I've got a better example than a windlass without a bucket)Jimbowley (talk) 10:05, 11 July 2012 (UTC)

Jimbowley, you can worry about when a machine is not a machine all you want, but please move on from the issue of a wheel and a wheel and axle as simple machines. Prof McCarthy (talk) 11:21, 11 July 2012 (UTC)

You can't answer my questions. You won't make a defensible argument. So I should just move on? Jimbowley (talk) 12:17, 11 July 2012 (UTC)

Do you even find my Kinematics argument interesting? I had hoped by taking it into your realm you might think 'hmmm, actually that is a bit odd'. Or are you just treating me as a lunatic to be ignored.Jimbowley (talk) 12:17, 11 July 2012 (UTC)

Important question about axle

I am questioning the functioning of any load carrying wheel so-called wheel before the invention of a metal axle, which would have prevented wood-rubbing-wood friction and a resulting fire. As important as this question is none of the axle, wheel or axle and wheel articles mentions it.Phmoreno (talk) 21:01, 25 September 2016 (UTC)

I found the answer to the axle question here: [1]

According to Bela Sandor, professor emeritus of engineering physics at University of Wisconsin at Madison:

King Tut chariots appear to be the first mechanical systems which combine kinematics, dynamics and lubrication principles. "The bearings are built exploiting the modern principle of a hard material against a soft material, and by applying animal fat between the surfaces. The grease reduces friction and increases running duration," said Rovetta When set in motion, immediately after initial start-up, the friction between the wood of the bearing, the grease and the wood of the wheel pivot heat the grease.King Tut chariots appear to be the first mechanical systems which combine kinematics, dynamics and lubrication principles. "The bearings are built exploiting the modern principle of a hard material against a soft material, and by applying animal fat between the surfaces. The grease reduces friction and increases running duration," said Rovetta When set in motion, immediately after initial start-up, the friction between the wood of the bearing, the grease and the wood of the wheel pivot heat the grease.

Phmoreno (talk) 18:38, 5 April 2017 (UTC)

Hinge?

If you're going to make up new parts to the age old wheel and axle then you need to explain wtf it is. 12.198.168.7 (talk) 18:06, 18 May 2022 (UTC)

This edit fixed that, I believe. Just plain Bill (talk) 19:26, 15 November 2022 (UTC)

Need to add greek

I really appreciate to add greek translation so i can READ 2A02:587:763B:6900:6508:AE66:489B:2A2F (talk) 14:30, 22 November 2022 (UTC)