43
votes
Why are bulldozers so slow?
I wonder why can't we engineer..
We CAN engineer a vehicle which is both fast, and has a lot of torque. (E.g. a tank, as you mentioned yourself)
The reason why we don't do this for a bulldozer (I.e. &...
- 736
32
votes
Accepted
Why is this bridge thickest above the support pillars instead of the mid-span where the bending stress is highest?
If I model this as a simply supported beam having load at mid span [...]
I suspect that this is where your analysis went awry.
First off, you should always model bridges with distributed loads, not a ...
- 13k
26
votes
Why are bulldozers so slow?
From memory, but pretty much realistic: a tank will use e.g. 1000 liters of diesel fuel just to move 100 km and will probably require a track maintenance afterwards. A truck with the same tank on its ...
- 499
8
votes
On a car with all-wheel drive, how does the engine provide the angled front wheels with power?
You could also include front-wheel drive in your question. It would be enlightening for you to look at what radio control rock crawlers do. It has much of the excess of a full-sized car stripped away.
...
- 4,897
8
votes
Why are bulldozers so slow?
Because the tracks or tyres and suspension needed for sufficient ground contact when pushing, dozing or grading does not match the suspension etc needed for higher speed situations.
Even the ...
- 15k
8
votes
Why are bulldozers so slow?
They need to be heavy for traction, which makes them too heavy for speed.
To have enough friction between ground and tracks, the machine needs to be very heavy. The Caterpillar D9 you mention weighs ...
- 1,943
7
votes
Why is this bridge thickest above the support pillars instead of the mid-span where the bending stress is highest?
Since this bridge is crossing over a waterway, besides aesthetics, the arch-shaped bridge provides several advantages:
Less restrictive over the height of marine traffic due to more headroom in the ...
- 7,999
7
votes
Accepted
Why excavators use Hydraulic motors for rolling or moving forward instead of diesel engine?
Yes, because many or most excavators can 360 rotate so getting a classic gearbox/ prop shaft drive to the wherls or tracks would be challenging.
Then sorting the ability to do forwards with one side ...
- 15k
6
votes
Accepted
What does this line with cross means in the blueprint?
The symbol or variable for diameter, ⌀, is sometimes used in technical drawings or specifications as a prefix or suffix for a number (e.g. "⌀ 55 mm"), indicating that it represents diameter. ...
- 9,794
6
votes
Why are bulldozers so slow?
You’d just need a lot of engine power and all the suspension, drivetrain (including tracks), brakes, safety equipment (seatbelts, airbags) etc. would have to be designed for the high speed. Just ...
- 318
5
votes
Direction of fluid flow
Heat the pipe at some point, and find the direction in which heat transfers. This will give you the direction of the flow.
Caution: Don't do this for flammable fluids. Thanks to @Carl Witthoft for ...
- 101
5
votes
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Why do we need continuum approximation in fluid mechanics?
Materials were intuitively uniform for 60,000 years. A few people started guessing they might be "atomic" about 3000 years ago. They only became rigorously atomic about two hundred years ago....
- 4,159
5
votes
Accepted
How can I connect a cylinder and block in a way that can be detached multiple times?
Figure 1. A slot and clamp screw provide an even clamping friction around the surface of the mating surfaces and doesn't leave grub-screw marks.
If forced to use a grub screw then a groove can be cut ...
- 9,794
5
votes
What is the best pattern of lightening holes to drill vertically (i.e. along the transverse plane) through a rod of aluminum
An axial hole.
That is why prop shafts on cars and trucks are hollow.
Even the transmission shafts between tractor to device, driven by the pto (power take off) are also hollow. Some are not round, ...
- 15k
5
votes
Origins of the "threaded fastener pullout formula"
(adding to DKNguyen answer, and giving a slightly different perspective --hopefully).
general calculation
The calculation is indeed based on a cylinder surface/plane that transfer the force from one ...
- 24k
5
votes
Accepted
What type of chain is this?
Looking at the photo, I believe the marking is not 890 but 06B, a standard size for roller chains according to DIN ISO 606 with a pitch of 9,525 mm.
- 1,853
4
votes
Direction of fluid flow
Yes, purchase an ultrasonic flow meter.
Needs a straight length of pipe and very careful placing of the sensors.
However, if done well one can get good results, if not then the results can be ...
- 15k
4
votes
Accepted
Torque Problems vs Motor Problem?
The motors have a rated speed of 2750rpm. It doesn't look like there's much of a gear ratio, so at the moment the motors spin at the same speed as the wheels. With 16" wheels, 2750rpm is about ...
- 156
4
votes
Accepted
Why is Scotch-Yoke mechanism not used for internal combustion reciprocating piston engines?
Making an engine using scotch-yoke mechanisms for all pistons on a multi-cylinder engine will increase the cost and add a lot of needless complexity and mass, especially rotating mass that won't ...
- 15k
4
votes
Can the crest of an ocean wave be increased by directing ocean waves to a center of a curved column?
Your idea has merit, and the fundamental principle involved is called impedance matching. Here is how it works:
For any power source we wish to harness, that source can be characterized by two ...
- 13.5k
4
votes
What is the strongest sheet metal screw for 1/16 inch aluminum sheet?
Have you considered a Thread Setter? (Reference: Marson Thread Setter kit) Drill a hole through your base, put in the thread setter insert, and crimp it down. Then you have a strong thread to attach ...
- 223
4
votes
Matrix Calculation
Your numbers are right. You are just confused about matrix multiplication. See https://en.wikipedia.org/wiki/Matrix_multiplication (or any linear algebra textbook):
For matrix multiplication, the ...
- 2,626
3
votes
Direction of fluid flow
If this is a pumped system, try measuring the reaction forces when you turn the system on. For example, if you're trying to measure the direction of fluid flow in a hermetically sealed "black box&...
- 310
3
votes
Why is this bridge thickest above the support pillars instead of the mid-span where the bending stress is highest?
Spreading the upward reaction load from the support pillars is one reason, the function of an arch translating vertical load to horizontal thrust is another. But there are already good answers saying ...
3
votes
Accepted
Airflow visible over the airplane wing
Specifically, what you are seeing here is a vortex which is basically a sideways tornado. Vortices occur when moving air forms a twisted stream when flowing over an object with a complicated shape. ...
- 13.5k
3
votes
Accepted
Relation between welding bead and outer diameter of a pipe?
Looks like ERW pipe with the ID trim die not working. The diameter is very small for DSAW ( double submerged arc welded) pipe and the ID weld bead looks too high. Or, I am wrong and it was welded from ...
- 6,057
3
votes
Accepted
Throttle position as a function of engine torque and speed
why does the torque value at a specific rpm vary for different throttle positions
This is the difference in acceleration when you fully open the throttle versus open it part-way. For a spark-...
- 5,875
3
votes
Accepted
How ground water is brought to surface if maximum suction head is limited to 10 meter?
So if you put the pump(s) at the bottom of the hole then the suction head is no longer, because you now need the pump(s) to overcome pressure head.
Of course you can use multiple pumps to do 10 meters ...
- 15k
3
votes
Accepted
What technology is behind a deep freezer door
On a different scale and with different and more severe temperature variations, consider the following:
Place a few ounces/tens of milliliters of water in a plastic bottle. Heat it to boiling in a ...
- 6,795
3
votes
Accepted
What are the practical solutions to manufacturing this mechanical piece?
should i use a CNC Machine? But is it gonna be able to make that shape, since there isn't much space for the "Drill Bit"?
On a mill, it is called an endmill, not a drill bit. I assume this ...
- 4,897
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