# Tag Info

49

Those are counterweights. They work exactly the same as those lead counterbalance weights on the wheels of your automobile. If they left those out, then those connecting rods and bearings would create an out-of-balance condition, and the wheels would vibrate at higher speeds. That could very well damage the wheels. But as a couple of others have nicely ...

28

Those are balance weights against the joints used for the rods linking the wheels together.

27

Car wheels have holes mostly due to weight and cost considerations. Each hole is a chunk of material that you aren't wasting and weighing down the wheel with. As another bonus, the holes help with cooling the brakes by allowing airflow between the inside and outside. The shape and size of the holes are calculated to have a minimal impact on the structural ...

19

Many of the answers so far have mentioned that part of the purpose of the holes is weight reduction, but most of them don't express why weight reduction in the wheels is important. There are two major reasons; the first (also mentioned by Steve Ives) is that the suspension systems in vehicles operate better if the 'unsprung' mass is kept as low as possible, ...

19

If you were going to turn left 90 degrees, without turning the wheels, then you wind up dragging the wheels sideways while you turn. 16 seconds into this video shows exactly what I'm talking about. So every time you try to back out of your driveway, or a parking spot, or turn into a parking spot, or turn anywhere for any reason, you're going to lay down ...

17

Mainly to reduce weight. A car's handling characteristics are improved by keeping the 'unsprung weight' (the weight of the car not isolated from the ground by springs i.e. the wheels, axles, hubs, brake disks, calipers, etc.) as low as possible. Holes in the wheels reduce this weight. The lower weight helps the unsprung portions of the car to follow the ...

15

The oversized counterweights on the second set of wheels are to help balance the additional inertia of the pistons, piston rods and crossheads, which are directly connected to the wheels on this axle. (In a former life I was a museum conservator and rebuilt, and operated, steam traction engines and a locomotive.) ronford

11

Assuming all the wheels are evenly spaced on the same circle, then more wheels is always more stable than less wheels. However, there is diminishing return as the number of wheels gets large. The metric of stability is how far from the center of the circle the center of mass can be before the chair tips over. The chair is stable whenever the center of ...

9

I laid everything out so you should only need to read it from top to bottom and look backwards for variables, never forward. I also tried to lay it out so hopefully you know where everything is coming from (as long as you have a basic understanding of power, torque, force, and friction...maybe even if you don't). $\mu_{roll}$ = coefficient of rolling ...

7

While it might be possible to design a rear-wheel-drive car in such a fashion that the front wheels basically operated as casters and the steering was controlled by driving the rear wheels at different speeds (some automatic guided vehicles operate on this principle), such vehicles perform poorly when there is a loss of traction at speed. If such a car were ...

6

The key feature is that the steering has Ackerman geometry This means that the steering arms coming off the back of the hubs are connected to the steering linkage at a point inboard and behind the pivot point of the hub. If you draw a line through these two pivot points for both wheels they will meet at or near the centre of the rear axle (although the ...

6

When a car turns the sideways force will pull the outer side under the rim. A angle sticking out will get worn off quite quickly. Also if a tire isn't properly inflated then the walls will bulge over and put more force on the outer side. Again a corner will get worn off rapidly under these circumstances.

6

The main reason is because when a car brakes/decelerates, the load is reduced on the rear wheels and increased on the front wheels. If your car was exclusively rear wheel steering you would lose steering in high speed braking. The converse does not occur because engine accelerations are typically much much less than braking decelerations. Forklifts are ...

6

As has been mentioned above the size of tires plays a major role. Let's assume the manufacturer standards for a wheel after improving the shaft allows 1/100 mm of play. This much play would encourage a small wheel to resonated while shimmying much more than a big wheel which would need much mor time to complete one turn. A 10 cm diameter wheel at 20 km per ...

6

These counterweights are found on all piston-driven steam locomotives (not just Soviet designs), and even a few types of diesel locomotive using connecting-rod drive. As other answers note, their purpose is to balance the weight and momentum of the connecting and drive rods, which would otherwise cause heavy vibration when running at speed, to the extent of ...

5

The Jeep Hurricane has four-wheel steering that allows it to pivot 360° without moving. But it's very complex and expensive. I would guess that skid-steer systems in general are heavier, bulkier, and more complex. And really, the only place they're particularly useful is when you need really tight steering. 99% of our driving has no use for really tight ...

5

The holes in wheels serve a few purposes. They reduce the weight of the wheel itself, although not by much. The holes in those particular wheels actually appear to be adding rigidity and strength to the wheel. The extra folds in the steel make it stronger than if it was just flat. The holes may also help prevent the build up of brake dust. I believe Ratchet ...

5

I think the "health and safety" regulation about 5 wheels is a compromise between stability and cost. If your weight is on the edge of the chair seat and the chair has only 3 wheels, it is much less stable if you are in line with one of the wheels than if you rotate through 60 degrees to be mid-way between two wheels. That might happen (1) because the ...

5

On reason is that die cast (alloy wheels) generally have an odd number of spokes. This is because having directly opposed spokes causes problems with residual stress distribution as the casting cools and shrinks (this is also why cast iron hand wheels often have S shaped spokes). So 5 studs tends to be a more convenient number, if only for aesthetic reasons....

4

Sailboat 2-speed winches do exactly this. Winding the handle clockwise directly engages the drum via one ratchet, and when you wind it anti-clockwise a different ratchet engages an epicyclic gear. Both directions move the drum in the same direction, and both ratchets prevent the drum from moving backwards. The key feature is two ratchets in opposing ...

4

It's for airflow to allow for extra cooling. In most situations, that extra airflow isn't going to help. But when you're doing heavy braking coming off of a mountain, it can make the difference between your being able to brake and your brakes failing from over-heating.

4

If you press a cylinder on a flat surface the contact pressure concentrates on the edges and becomes very high. We call that edge stress condition. If the cylinder has a profile (curved instead of straight) it causes the pressure distribution to be more even and hence lower in value. If you want to account for the slight angles at which tires approach the ...

4

To add to @ratchetfreak's answer, there 2 more reasons: 1. Manufacturing process It's much easier and more reliable to make a continuous surface that us bevelled, that an angled surface from rubber material. 2. Stress distribution For the same reason why airplane windows are rounded, car tires are beveled. Stress is much better distributed when surface s ...

4

Consider what happens in front wheel steering, such as an automobile: Turn the steering wheel slightly clockwise. The front wheels each turn slightly clockwise. Their rolling action causes the wheels to pull the front end of the vehicle slightly to the right. The back wheels follow the track of the front wheels, but in a slightly tighter turn. Holding the ...

4

Consider an alternative to the current placement of the cans. The image above from the Pinterest web site, UN Food and Agricultural Organization shows a wheel in which the cans (bamboo tubes) dump the water to the side into a trough. I'm not suggesting that you duplicate this design, but if you turn your cans slightly to the side, you can have a chute or ...

3

Yes I agree, the "moment of inertia" is a factor in making "spoked" wheels, the holes in pressed wheels will reduce weight, and allow circulation. The truth is, for this kind of wheel, it is largely cosmetic. It also makes them easier to manually handle (finger holes). For this type of wheel it would not make a lot of difference if they were not there. ...

3

Before we dig into practical equations, I'll just say that tires are surprisingly complex in their behavior. There are a variety of equations that try to fit the experimental data reasonably well. Hard to say that any one is right or wrong. That having been said, the first equation is pretty inconsistent with the everything that I've ever seen. Weight on ...

3

The complication here is that the simple relationship between wight (or downforce assisted equivalent) coefficient of friction and traction is only true up to a point and in performance tyre that point is where the thermal and mechanical loads on a tyre start to change its mechanical properties. Performance tyres are generally designed to work best with a ...

3

Quite a few of the machines allow to tilt the pair of wheels to arbitrary angle too. Some allow tuning speed of the two motors separately. It's all about curveballs and Magnus Effect. One wheel going faster will give the ball a spin on top of the forward speed - and the ball trajectory will curve in direction perpendicular to rotation axis and current ...

2

The actual parameters for real tyres tend to be heavily protected intellectual property, you won't find those anywhere. However, have a look at these various pages, they give indicative values of the various parameters: Pacejka ’94 parameters explained – a comprehensive guide Pacejka's Magic Formula An Alternative Method to Determine the Magic Tyre Model ...

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