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56 votes
Accepted

Why are railroad tank cars bent in the middle?

As other have pointed out, the main utility is to allow easier cleaning of the tank cars from sediment (solid precipitates). Usually, there is a drain in the lowest point. The reason that it is in ...
NMech's user avatar
  • 24.3k
35 votes

Why does this fence have a kink?

They're V-Mesh panels. V-Mesh panel from Irish Wire. The offset of the vee gives rigidity in the horizontal direction. The vertical rigidity is addressed by the fence posts. It's available in 2, 3 or ...
Transistor's user avatar
  • 10.8k
20 votes

Why don't motorcycles have as good a turning radius as bicycles?

The simplest answer to the question is "because the motorcycle gets in its own way" Take a look at this picture of a trials motorcycle; it has perhaps the smallest of turning circles ...
Caius Jard's user avatar
17 votes
Accepted

Involute gear curve when root diameter falls below base diameter

In general, each tooth of an involute gear is made up of two curves: the involute curve and the root fillet. The involute curve is essential for gears to operate properly, and allows power to be ...
Involute's user avatar
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17 votes
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Would a centrifugal flyweight governor system slow down the descent of an object that is free falling down to the Earth's surface? (Revised design)

Once the cylinder is released and starts to accelerate downward, the rotating flyweights should pivot upwards to a certain degree (as shown in the drawing) and should act as a drag on each of the ...
jpa's user avatar
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16 votes

Why don't motorcycles have as good a turning radius as bicycles?

A bicycle usually weights about 18 pounds versus an average of 180 pounds for a motorcycle. In tight turns a bicycle can easily be controlled by the rider shifting their body's center of mass as ...
kamran's user avatar
  • 22.4k
14 votes

Is this dropout design as bad as I think?

An ideal dropout design would...... OK, already there you've gone into the weeds. There is no ideal dropout design. Engineering real world things is a balance of tradeoffs. You have to balance the ...
whatsisname's user avatar
14 votes

Why are railroad tank cars bent in the middle?

Same reason the Corsair fighter has bent wings. Makes clearances easier. Look at the lumpy, sticky-outy things on a tank car. You have the trucks/bogeys at the end bottom... and the massive fill ...
Harper - Reinstate Monica's user avatar
13 votes

Why aren't screens round instead of rectangular?

The earliest CRT displays were in fact round. However, that was more due to manufacturing tradeoffs of making large glass envelopes with vacuum inside than a desire for the display area to be round. ...
Olin Lathrop's user avatar
  • 11.4k
12 votes

Do outer fillets|chamfers also reduce stress as inner ones do?

Sorry for not taking your "Thin Hollow Brick-Shaped Object" as an example - I felt a standard notched test specimen would illustrate the principle more clearly: It can be seen that adding external ...
Jonathan R Swift's user avatar
12 votes
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Is it useful to stuff my glasses with newspaper to protect them?

In itself putting paper inside a glass will make very little difference. Glass is a brittle material and tends to fail by shock and point loading. Its static tensile strength is actually pretty good. ...
Chris Johns's user avatar
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12 votes
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SOLIDWORKS - 3D Sketch of Trombone

See the .gif below! EDIT: You may need to enable visibility of these handles if they're not on by default - it depends on your default profile/settings.
Jonathan R Swift's user avatar
12 votes
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How to work on big CAD project in team?

It's a massively important question. Short response: apply the concept of encapsulation. Divide into subsystems During development, assign design-ownership (distinct from project manager role, ...
Pete W's user avatar
  • 1,561
10 votes

Why are railroad tank cars bent in the middle?

So any sediment will collect there as part of cleaning. Then other designs have a more pronounced bend to allow for the bogies and also keep the height down - some tunnels are lower.
Solar Mike's user avatar
  • 15.8k
10 votes

Why does this fence have a kink?

Bending adds rigidity. Take a piece of paper, fold it, the bend gives it a rigid form to hold more weight. V-Mesh fences are also used in equestrianism as horse fencing helps keeps predators out and ...
LazyReader's user avatar
10 votes

Do I need a pressure relief/safety valve if my pump can't exceed the rated system pressure?

Not a plumbing engineer, but: What about thermal expansion? You reach a dead end, pump stops. Pumps often have a checkvalve that prevents backflow, so you have now created a pressurized container. ...
Thomas's user avatar
  • 109
9 votes
Accepted

Why are spur gear ratios not always whole numbers in practice?

Gear ratios can be referred to as hunting and non-hunting ratios. In a non-hunting ratio, any one gear tooth will contact its corresponding gears' teeth in the same place every time. In a hunting ...
Todd's user avatar
  • 116
9 votes
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Why don't motorcycles have as good a turning radius as bicycles?

I'll approach this from a different perspective to the other answers: Pushbikes have no limits on the steering range because they don't need to add the complexity and weight. They're simple, light, ...
Chris H's user avatar
  • 396
8 votes

Why do car-seats have an expiration date?

It's a combination of 1, 3, 4, the product development cycle, and the nature of the product. 1 - Damage in materials is a cumulative process, the product of hundreds or thousands of little events (e....
DLS3141's user avatar
  • 2,145
8 votes

Is it useful to stuff my glasses with newspaper to protect them?

Filling inside the cup with paper is just to lock in the wrapping of the same paper around the glass. It also offers coverage and protection of the rim of the glass. Because of the integrated, all-...
kamran's user avatar
  • 22.4k
7 votes

Do longer gun's barrel improve accuracy?

The short answer: Yes, a longer gun barrel improves accuracy. Theoretical accuracy of handguns and rifles is driven by rifling, barrel length, and bullet mass. Rifling: When the bullet travels ...
OnStrike's user avatar
  • 743
7 votes

Magnetic Entrapped Storage at 0 gravity

Flywheels are used in space, but not for storage of energy. They are used for attitude adjustment, as the spinning of a large mass has significant implications in an object which is free to move. ...
Rory Alsop's user avatar
7 votes
Accepted

Why is it more common to use ceiling fans instead of air pumps?

Mainly cost difference. And also, a fan is sufficient for the job. The problem being solved is thermal stratification. That's caused by a lack of vertical mixing; the warm air rises to the top, the ...
410 gone's user avatar
  • 3,761
7 votes
Accepted

What's the best way to design a joint with two fasteners?

I think you might have a misconception regarding to how far the pressure from the fasteners extends. One subject you might want to have a look into is "bolt joint stiffness". The most ...
NMech's user avatar
  • 24.3k
7 votes
Accepted

On steam locomotives with six driving wheels, why are the rear set of wheels placed further apart from the other two?

In the ones pictured, there are no trailing axles - they are a 2-6-0 and a "tenwheeler" 4-6-0 respectively. The ones shown have the firebox between the two rear drive axles. .That was an ...
Phil Sweet's user avatar
  • 4,755
6 votes

Why don't public transport networks have more routes to each terminal?

The main reason is economics. Who is going to pay for all the additional lines? The other part to this is, will the additional lines have enough passengers to make them profitable and sustainable? If ...
Fred's user avatar
  • 9,687
6 votes

Why don't public transport networks have more routes to each terminal?

Keep drawing combinations. You forgot Østerås to Vestli, Østerås to Bergkrystallen, and every other combination of possible origin and destination. This breaks down in a hurry. By the time you ...
Harper - Reinstate Monica's user avatar
6 votes

What is "reversal" in mechanical engineering drawing?

It approximately means it is allowed or forbidden to have scratches at the place of round. When you are making cylinder surface you can to do it many different ways: milling, welding, soldering. In ...
Andrew Kachalin's user avatar
6 votes

Is this dropout design as bad as I think?

The dropout is a single stamped piece of steel, and that shape has been used on millions of bike for decades. No the dropout design is fine. Normally the top line of the derailleur would be in-line ...
Criggie's user avatar
  • 430

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