# Tag Info

27

There are a few simple reasons why the speed of a vehicle (road conditions notwithstanding) may be limited: Gearing -- Production vehicles with conventional transmissions have a limited number of gears. For most modern cars, this is usually 5 or 6, whereas older vehicles may have as few as 2 or 3. If the gear ratio of the highest gear is too low ("lower" ...

11

So, what limits the speed is a combination of two things : the power from the engine with the gearing and the rolling and air resistance. Up to approx 40mph the rolling resistance is the largest resistance, but above that speed air resistance is the dominant factor and increases the faster you go. The engine power is fixed (ok tuning etc) but the gearing ...

9

Physics stops you. Ever ride a bicycle? 25 mph is easy, 30 is hard, 40 requres special gear or a very pumped up body, and 50 is nigh impossible. Why does the effort get so steep for such small speed increases? Air. Aerodynamic drag Rolling resistance is the dominant factor when your car is going slow - that's why they're so hard to push. But at higher ...

9

Simply put, power transmission is not free. Every time you have some energy over here, and you want to move it to over there, you are going to lose some of it in the process. In this case, if your engine is in the front and you want to drive the back wheels, you'll need some combination of gears, bearings, and shafts to transmit that power. Gears are ...

9

TL;DR: The kinematic constraint imposes the redistribution of forces on the four wheels. This redistribution is permitted due to the car differential. IMHO it is easier understand this if you first understand the difference between kinematics and kinetics. kinematics: are about the geometry of motion (kinematics don't take into account forces or work). ...

8

ICEs (internal combustion engines) take some time to ramp up their output torque. Various mechanical systems have to react before more mixture is injected into cylinders, and that then makes more pressure upon combustion. Think of a throttle-body engine as example. You push on the gas pedal, which opens the throttle valve more. That causes more air to ...

7

It isn't an ordinary video camera. It's a high-resolution LIDAR that uses laser beams to measure the distance to thousands of points on every rotation. I believe the one used by the car in that video is the Velodyne HDL-64e, which I have used myself on a similar project. It sends out a vertical array of 64 pulsed laser beams and uses time-of-flight to ...

7

They are external air filters for the engine.

7

No. All the wheels, axles, brakes and parts of the suspension would remain in the same position relative to the ground so their contribution to the centre of gravity doesn't change. The overall CoG will decrease by < 50 mm. Figure 1. For your calculations you can just consider the heights of the two CoGs when calculating the overall CoG.

6

This is a simple explanation/observation. A two-wheel dolly rotates along a circular path by a constant torque (T). The position of the wheels changed from point 1 to point 2 in one second (t = 1s), what you can say about the distance that each wheel has traveled, and what is the speed of each wheel at the turn? ADD: I think it is imperative to understand ...

5

Paparazzo pretty much nailed it, but I'd like to add a few things. Regenerative braking is certainly a large part of it, but there are other synergies when utilizing multiple engines in an automobile, too. The ICE can be smaller and sized closer to what is needed for normal operation instead of peak power since the electric motor helps the ICE during the ...

5

The difference is the regenerative braking. It take as much work to decelerate a car as to accelerate. I don't know the actual efficiency but even 50% recovers a lot of the energy that would have been lost as brake heat and brake dust. The electric assist control is also tuned to let the gasoline engine operate in a range where it is most efficient. ...

5

I think the instant torque claim mostly applies to "off the line" acceleration. That is from a standstill and electric motor has 100% of its available torque available at 0 rpm (mostly). The tradeoff is the an electric motor is always going to see a drop in torque with speed. Generally when you compare wheel torque availability as a function of speed between ...

5

In order to change the speed of the inner and outer wheels, there must be additional torque(s), which must be different for the two wheels. What is this torque, and where does it come from? If the car is turning, there must be a torque relative to the center of mass of the car (note that torque is always relative to some axis; the torque on the car as a ...

4

That's a lidar sensor, which is making a continuous 360 degree sweep, rather than a camera which has a field of view as such. Rotating mirrors are a fundamental part of how the system works. Note that in the video the system represents traffic as fairly crude boxes rather than rendered images, so it may be looking specifically at reflectors, which also ...

4

It depends on what type of differential it has. The nature of an open differential (as found on normal road cars) is that the spinning wheel(s) will get all of the torque. Proper off-road vehicles will usually have a diff-lock selector which works on some of all of the differentials which means that both driveshafts the diff is connected to get the same ...

4

Vertical loading does (almost) nothing to a properly designed and constructed bitumen road surface, it is horizontal loading that causes deterioration. Horizontal loading comes from acceleration, braking and turning. For acceleration and braking speed is unimportant, it is only the rate of change of speed that matters. For turning, speed can in theory make ...

4

A truck speeding down a highway creates an envelope stream of high pressure air surrounding it. This is basically a wake, composed of layers of high pressure shockwaves, created when the front of the truck, hood and cabin penetrate the still air and push it open. This shockwave moves with the truck and after turning into a small turbulent tail at the ...

4

It depends. The driven wheels need to be connected by a differential whcih allows power to be transferred to both wheels but still allowing them to turn at different speeds. It's not that easy to comprehends exactly how this works mechanically without having a physical model to play with but it does work , at least within certain limits. The problem ...

4

Because the rear wheels are larger so the hitch connection point is below the centre line of the rear axle. However, if there is enough power then the tractor can do a wheelie anyway, have a look a tractor pulling competitions...

3

Usually because the strengthening in the filter is optimised for one direction and the layers may also be optimised so the oncoming air is met with a coarse layer first, followed by successively finer layers.

3

Clutches do indeed carry quite lot of force but when you pull away from stationary the correct technique is to use fairly low revs and blend the clutch in quickly but smoothly. In this case the clutch is only slipping for a second or so and the torque involved is fairly small. If you are more aggressive or slip the clutch for long periods you can indeed wear ...

3

No, it's a characteristic that electric motors produce most, if not all, of their torque from zero rpm - which is why the electric cars are so good at getting off the line and how electric motors don't always need gearing to start heavy machinery - just lots of energy...

3

If you have a 20 ton truck sitting stationary on the road, it's exerting 20 tons of force on the roadway. If that truck is traveling at 100km/hr, it is still exerting 20 tons of force on the road. I'm sure this is why your friend says that weight is the only factor that matters. The truck stopping or starting isn't even a major concern because that ...

3

In high speed collisions essentially the human body fails under high g negative acceleration even if the structure of the car or cabin or test vehicle is strong enough to survive the collision. strange things can happen that may not immediately be visible such as brain injury due to boiling of Cerebrospinal fluid because of the vacuum created by rapid ...

3

The difference is in the drag coefficient. Typical drag coefficient of the 50's cars have been in the range of 0.38 to 0.42 or so. typical drag coefficient of modern cars even the ones not renowned for their streamlined body is ranging from 0.26 to 0.34. drag is the retarding force exerted on moving bodies by the media they are moving in. it tries to slow ...

3

According to the wiki regarding pitch stability in aircraft, the terminology generally refers to the tendency of an aircraft to not diverge along the lateral axis when the stable configuration is slightly changed. That is to say, a level aircraft can be nosed over (pitch down) which will result in the aerodynamic forces causing the nose to raise itself, ...

3

Multiple Clutches Many manual transmissions feature just a single clutch between the engine and the transmission. This requires that the clutch be disengaged before switching gears, during the switch, and until the final selected gear is fully engaged. When a human is performing this operation, the clutch may be engaged for many hundreds, even thousands of ...

2

To answer this question, you need to consider the failure modes you are protecting against. To understand the failure modes, you need to have the full details related to the materials of the road, thicknesses of the respective materials used to pave the road, and etc. A bitumen road running heavy trucks will most likely fail by excessive rutting in my ...

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