Wednesday, September 24, 2014

Car Talk 101 Transmissions

Types of Transmissions

There are many different types of transmissions; here is a brief explanation of the major ones.


Please remember that I am in no way an expert. These are just simplified explanations and any videos that I have links to are not mine and any credit should be given to those who made them. 

Manual:

This can either be a 5, 6, or even a 7 speed transmission (trans). Manual transmissions use 3 pedals; a gas, a brake, and a clutch. Instead of the car going from each gear by itself, the driver has to physically push the trans into a new gear by using the clutch pedal and the shifter. It can be tricky for some as while you change the gears you also need to make sure the engine revolutions (revs) are in the right area. So basically you start off in first gear, you accelerate, then once the revs get close to the higher end you ease off on the gas. You press down on the clutch, move the shifter into the second gear and slowly take your foot off the clutch while keeping the gas pedal steady so when the new gear connects the engine doesn't spin too slow and stall. Manual transmissions are usually better in situations where you need complete control over the engine and wheel speed, such as in snowy or wet conditions, going off-road, racing, or towing. There can also be what is called a sequential manual, which means that you can only shift up or down one gear at a time, so you cannot skip from 4th to 1st. These are usually used in racing. Here is a link to a video that should help explain it:


Most transmission are based of the manual trans style.

Automatic (auto):

These are basically like the manual trans but instead of there being a clutch pedal it is all controlled by a computer system. The car will shift automatically up and down based on gas input and the overall speed of the car. They can be had with 4,5,6,7, or even 8 speeds. These are the easiest systems to use as everything is basically done for you, all you do is put it in drive and it does the rest.
There are also what people call a semi-automatic trans. This is a normal auto trans but it has the option for drivers to manual select the gears usually with the shifter, buttons, or paddles on the steering wheel. In this case the manual selection works like a sequential manual. Most auto cars now have this feature.

Dual Clutch Transmissions:

I had briefly covered this in the VW posts. In short they are like having 2 manual trans in one system. They use 2 clutches, one for the odd numbered gears and one for the even number. Essentially while one gear is currently being used, the next gear is also pre-engaged. This allows for much faster and smoother gear shifts. These trans are usually automated so there is no clutch pedal, they also usually have a manual shift option. These transmissions work very well and fast and give the cars a sporty feel. 

Continually Variable Transmissions (CVTs):

I have also briefly explained this as well in a previous post. A CVT does not have any gears or clutch; they usually just consist of either a rubber or chain belt and two pulleys. These pulleys usually usually consist of 2 cones that make an hourglass shape. The cones can then be pushed closer together or father apart, this action essentially makes the part of the pulley where the belt is going around larger or smaller. With this action the CVT can essentially have an infinite set of gear ratios, but in a lot of car manufacturers they will have preset spots for the CVT to stop that simulate normal gears that can then be selected through the shifter like an automated manual. CVTs tend to be louder than normal transmissions due to their main strengths. CVTs are great at keeping an engine constantly running at either its peak power or its peak efficiency areas. This means while accelerating the engine will be at a constant higher RPM than normal ones that have to go through gears, this constant drone can be quite loud and annoying for smaller less powerful engines, unless ample sound insulation in included. Another great thing about CVTs are that they are much lighter due to fewer parts and they are more simple meaning less to break and go wrong or less top fix if something does. CVTs will eventually take the place of conventional auto trans. Nissan was really the first big manufacturer to implement CVTs into a number of their models but currently Honda and Subaru seem to make the best ones.

Electric Motors:

In most electric cars they don't have transmission due to electric motors being variable both in speed and torque based on how much power is given to them. This is a great advantage meaning they can save weight which will eventually be taken up by batteries. 


Who knows what type will come next?

Hope you enjoyed this little info post, I will try to include a few more on things like HP vs. Torque, different types of driving wheels, and who knows...

If you have any suggestions please leave a comment and/or follow! 

J.K.



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