25
votes
Accepted
How do the latest automatic transmissions match the efficiencies of manual gearboxes?
Traditionally...
The major drawbacks of automatic transmissions were:
parasitic losses in the torque converter, something which manual transmissions don't have.
fewer gears, so a given engine was ...
- 39k
23
votes
Why is the speed of a motorcycle measured at the front wheel?
There are pros and cons of each, remember you can easily spin or lock up the rear wheel, and in fact the rear wheel may be far less often at the correct speed.
So the decision on this stems from ...
- 18.6k
21
votes
How do the latest automatic transmissions match the efficiencies of manual gearboxes?
A lot of new automatic transmissions (e.g. Volkswagen DSG) arent actually auto transmissions, at least not in the traditional sense. They have a normal computer-controlled dry clutch (well two ...
- 1,350
13
votes
Accepted
Why is the speed of a motorcycle measured at the front wheel?
Its not a rule of thumb that the Speedometer is connected to the front wheel.
There are many Suzukies and hondas in my country that have the speedometer connected to the rear wheel.
As Rory stated, ...
- 8,946
13
votes
Factors Limiting EV Battery Acceptance Rate on DC Fast Chargers
Generically speaking, higher charge rates will heat a pack more quickly than the lower rates. Tesla models are designed and constructed with active cooling as well as appropriate monitoring and charge ...
- 4,305
12
votes
Why is the speed of a motorcycle measured at the front wheel?
The front wheel is used in most cases with mechanical speedometers (though there are exceptions) because it's just easier (and probably cheaper) to couple the front wheel to the mechanism.
...
- 581
10
votes
Oil Cooled vs Water Cooled
I am assuming that by cooling you are referring as to which Engine cooling systems are better in particular scenarios...
Oil-cooled:
Traditional Oil-cooled engines are most commonly found in passenger ...
- 101
9
votes
Accepted
How did luxury cars provide smoother rides without active suspensions?
Assuming they were the base models, the two cars you mentioned (Acura TL and Mazda6) are both Front-Wheel Drive (FWD), while the Mercedes is Rear-Wheel Drive (RWD). The FWD cars, having both their ...
- 6,037
8
votes
Accepted
What is a sprag unit and what does it do?
A sprag is a kind of clutch that will turn in one direction but not in the other.
There are many designs but the common one is a set of balls on ramps. When going the wrong way the rollers run up ...
- 16k
8
votes
Accepted
What is Lobe Separation Angle (LSA)?
Lobe separation angle is affects overlap between the intake and exhaust valves which can effect emissions, performance and efficiency.
Example of Lobe Separation Angle
Measurement of Lobe Separation ...
- 32.9k
8
votes
Accepted
Designing IC engine
This looks like your first posting with Motor Vehicle maintenance and repair site. It looks like you are an engineering student, looking at a possible school project. Is that right? Welcome to the ...
- 6,549
8
votes
Accepted
Oil Cooled vs Water Cooled
Oil Cooled and Water Cooled are terms used by Manufacturer's to differentiate the slight difference between the cooling systems.
Note that this is specific to only motorcycles as almost all of the
...
- 8,946
8
votes
Accepted
Cast or Forged Wheels, is there any real-world difference?
I think bubbles are less likely to have anything to do with it. The forging process makes the metal more durable by aligning the grain of the metal. After forging, there is less of a chance for stress ...
- 148k
8
votes
Accepted
How do seat belts function?
I am assuming that you don't mean to ask how the belt holds you in place. :) I'm assuming you are asking how the mechanism works. I'll break this into two parts. The simple mechanism and the ...
- 5,245
8
votes
Factors Limiting EV Battery Acceptance Rate on DC Fast Chargers
One of the issues you face is that the battery capacity is itself one of the limiting factors for the power a battery can take. This is typically referred to as C-rating. That means you can charge a ...
- 181
7
votes
What are the problems in building 2 stroke engines with a large displacement?
I know this thread is a bit old, but Detroit Diesel and GM EMD (Electro-Motive Division) have many 2 stroke Diesels.
The crankcases! Well they aren't pressurized. How it works is different to a ...
- 71
7
votes
Accepted
What is a stress riser?
A stress riser (also known as a stress concentration or stress raiser) is so called because there is more stress in one area which can cause fatigue cracks and ultimately cause part failure. This can ...
- 148k
7
votes
How do seat belts function?
To add to the other great answers, I must point out that seat belts 'work' to reduce the impact on the passenger by stretching. In a large impact the fabric stretches quite significantly, don't ...
- 311
6
votes
Why is the speed of a motorcycle measured at the front wheel?
All of my competition cars have had speedos, some of which didn't work at all. I have never once been in a race and had time to take my eyes off what was happening around me to look at the dials. ...
- 23.4k
6
votes
Accepted
Keep Alive Memory (KAM)
KAM remains powered when the ignition is off due to the fact it receives power from the battery. It is the same as RAM in the sense that it is a volatile form of memory and will lose its data if power ...
- 316
6
votes
Accepted
Location of exhaust manifold
It all comes down to how the engineer designs it. The manufacturer sets how it's going to be put together. There's no real inherent design differences +/- ... It could come down to whether they want a ...
- 148k
6
votes
What are the problems in building 2 stroke engines with a large displacement?
Perhaps you were thinking of 2-stroke gasoline engines when asking the question.
Evinrude built a 3.6 liter gasoline 2-stroke for outboard boat motors.
http://www.roadandtrack.com/car-culture/...
6
votes
Accepted
Why is martensitic steel used instead of grey cast iron for ATV disc brakes?
I was looking at this from an automobile standpoint wondering What the heck is he talking about?? The vast majority of vehicle rotors and drums are made out of grey cast iron!, then went back and ...
- 148k
6
votes
How do the latest automatic transmissions match the efficiencies of manual gearboxes?
With a greater number of gears in the autobox and with a lock-up function called more frequently for the fluid flywheel.
Then add a better computer based control system for moving between gears : ...
- 34.5k
5
votes
Why is martensitic steel used instead of grey cast iron for ATV disc brakes?
Grey cast iron possesses some traits which makes it less desirable than martensitic steel for brake disc applications:
it is more brittle, which means it is easier to crack
it has very low impact ...
- 39k
5
votes
Accepted
How does a transfer case split power between front/rear?
TLDR : Planetary center differential with viscous coupling.
EDIT : This is wrt center differential transfer case and not traditional 4X4 transfer case , since the question is about torque biasing ...
- 2,196
5
votes
Cast or Forged Wheels, is there any real-world difference?
For the average user, the answer is no. There have been tests done to determine which one actually works better, and it was determined that the forged wheels did provide for better acceleration ...
- 5,245
4
votes
Location of exhaust manifold
Exhaust at the front is the traditional arrangement, it allows the exhaust to be cooled by the air that's come through the radiator (ok, not cold air but still cooler than the exhaust) and allows an ...
- 781
4
votes
Why do modern vehicles omit a temperature gauge?
Your sample may just be non-representative.
All the ones I know (I'm mostly into Japanese performance cars) have oil temps. Even many non-performance cars have an indicator that goes out once the ...
- 18.6k
4
votes
Keep Alive Memory (KAM)
From what I have seen, "Keep Alive Memory" can be cleared by removing power from the car by disconnecting the battery. ROM is "Read Only Memory" and is permanent at the chip level. Yes there are ...
- 9,316
Only top scored, non community-wiki answers of a minimum length are eligible