48

In an automatic transmission there is a ring with teeth on the output shaft of the transmission. When the transmission is shifted into park a lever called the parking pawl is lowered against the ring. If the parking pawl did not land squarely into an opening in the ring the car will roll slightly and there will be a usually an audible click. The parking pawl ...


44

This is one of those things which are easier said than done. To start with, let me show you a picture of a four speed transmission which has been blown apart: All of those hundreds of parts go through the front end of the transmission. If a single part is bad (which it usually is not the case), you have to pull all of this apart in order to diagnose and ...


29

The reason that an automatic doesn't stall out while "in gear" and at a stop, while a manual transmission does, is that automatic transmissions use a hydraulic torque converter to connect the engine to the transmission, while manual transmissions use a friction clutch. These two systems do a similar job in a very different way. A torque converter uses fluid ...


24

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 more likely to be in its sweet spot with a 5-speed manual than a 4-speed automatic during regular operation. gear selection logic which was inferior to well-...


22

Manual transmissions (most, but not all) lubricate not through a pump, but through the action of the gears and secondarily through the level of the transmission fluid itself. In some transmissions, the lower gears in the transmission, which touch the pool of fluid at the bottom of the transmission, transfers fluid through contact to the upper gears. In this ...


21

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 actually) so they do not need to move around a lot of transmission fluid like traditional automatic transmissions do. Also they have a lot of gears (7, 8 or even 9 ...


20

Old automatic transmissions were shifted entirely using hydraulics, not electronics. For this operation the transmission would generate 3 pressures; line pressure, throttle pressure and governor pressure. Line pressure is generated with the front pump of the transmission. It is used to actuate clutches and bands. Throttle pressure is a derivative of line ...


19

To put it bluntly, they had to implement a fuzzy logic analog computer based on hydraulics rather than a digital computer based on binary states: As usual, How Stuff Works has a reasonable introduction to the basic concepts with enough vocabulary to kick off more detailed research if you're really interested. That link will take you directly to the ...


19

For general driving, you can leave the car in drive. It doesn't damage the transmission leaving it in drive while stationary at the lights - although you don't want to be doing silly things like revving the engine while holding the brakes on. In an automatic car, you don't really use neutral. It is a step on the way to selecting Park, which means that the ...


15

It is important to note that revving the engine on an automatic transmission car while holding the car stationary with the brakes causes premature transmission wear and early failure. This action causes the fluid to overheat. It also damages the torque converter and driveshaft or cv joints. If you look at advertisements for performance torque converters ...


15

Sport mode will "increase pickup" by providing a more instantaneous response to throttle inputs. As akadian mentioned, the car will stay in lower gears as you accelerate, allowing the engine to stay in the optimal rev-range for higher torque output. The computer, by activating sport mode, will also not have to 'think' about what gear you should be in for ...


14

The main purpose of neutral on an automatic is for towing or pushing the car. Obviously you can't push it with the transmission in park, and if you tow it with the transmission in gear or in park and the drive wheels are in contact with the ground, you'll ruin your transmission or your tires or both. I'm sure there are some other uses too, but they're ...


14

They will probably work out to be the same. An automatic transmission is inherently more complicated which means more can go wrong and usually does (more so than manuals). The increased complexity also makes them more expensive, heavier, less fuel efficient etc. A manual transmission is less complicated which means there is less that can go wrong. Through ...


14

There's nothing wrong with the vehicle, from what you've described. It sounds like it's doing exactly what it's supposed to. I'm not sure you understand how to get out of a slide (or snow), which admittedly isn't particularly uncommon. "Gunning it" won't help, because your wheels are more likely to spin, which just tends to dig you deeper into the snow. ...


14

According to NY Daily News, only 6.5% of cars in the United States were Manual Transmission in 2013. That number may even be an overestimate. More helpful is Fix.com, which actually has a useful chart:


14

To go down hill By setting L (or 1 or 2), the gear will stay low and you will be able to use engine brake, instead of using brakes all the way down the hill and suffering from fading. The transmission will not necessarily pick a lower gear when going downhill, although they will pick a low gear if you are going uphill. Never brake the car for an extended ...


13

When the car is in D and you start the engine the hydraulic pump in the automatic transmission is not providing fluid pressure until the engine starts. This fluid pressure is used to engage clutches in the transmission to engage first gear or reverse. An automatic transmission does not have gears like a manual transmission which are physically meshed into ...


13

Putting the transmission into "Park" engages the "parking pawl" - essentially a metal pin that locks the output shaft of transmission (and thus the driven wheels) in place. As to why it exists - it is intended as additional roll-away protection that complements (rather than replaces) the handbrake (which, as the name implies applies actual brakes - usually ...


12

A lot of newer cars are smart about shifting (they have electronic solenoids to control the hydraulics). I can put my 2001 Nissan Pathfinder in reverse at 50 MPH, and it's smart enough to not engage, it goes into neutral. However, at speeds below its cutoff point (I've done it at about 15 MPH and regretted it), you can put a lot of stress on the drivetrain ...


12

Most owner's manuals state that the vehicle should not be towed with the drive wheels on the ground for longer than x miles or faster than y MPH. The reason for this is that Neutral only disengages the engine from the transmission, but not the transmission from the wheels. As the drive wheels turn, the transmission turns. This can heat up the transmission, ...


12

The somewhat longer answer is that the device that makes what you're asking possible is the torque converter. This device is a pair of curved blades setup as an impeller, and a turbine. The following cutaway pictures illustrate this setup: Here is a torque converter split in half for a better view: The way this works is explained really well by a You-Tube ...


12

The difference comes down to the driver. While automatic racing gearboxes can beat a driver when it comes to performance, for the type of vehicle you describe, a manual can perform significantly higher than an automatic if the driver knows how to use it. But then if you really wanted high acceleration you would choose a different car. Maintenance is much ...


12

No. Not by any significant or even measurable amount. Constantly using the shifter may, over time, wear the bushes and linkages prematurely but these parts are usually inexpensive and simple to replace. The transmission itself will be unaffected.


11

NOTE: I have anecdotal vs. empirical data on this, so please understand that caveat. I believe the problem which is actually being discussed is doing a transmission flush when it has never been done before (or with long periods without). The theory is, over time, buildup occurs within the transmission when flushes do not occur at regular maintenance ...


11

The power losses in a MT are primarily do to friction. Everything in a MT is positively locked together, meaning there is no slip anywhere. Beyond friction at least one of the rotating assemblies is partially submerged in the gear lube to provide splash lube for everything else. Stirring the fluid looses power. In an automatic everything I just mentioned ...


11

The transmission has a lock up torque converter. The torque converter sits between the engine and transmission. It is kind of like a clutch on a manual transmission car. When the engine is idle, it is barely engaged, so the engine will not stall. It will engage harder and until a certain RPM. Torque converters will always have some slip in them until ...


11

There are two main things about tranny fluid: Transmission fluid is checked when it's hot (up to running temperature). As the fluid gets up to temperature it expands. If the fluid is cold, it won't give the proper level reading, thus overfilling will ensue. One of the main fluid compartments of the transmission is the torque converter. When full, the fluid ...


10

This is a bad idea for several reasons. First, you run the risk of a runaway car. Second, you risk damaging your transmission, which could cause the runaway car in the first place. Thirdly, in newer fuel injected cars, you can actually get worse gas mileage. Let me explain. As stated before, by not having it in gear, you run the risk of your car getting ...


10

For a car that has 4, 5, 6 and 7 gear options, if all else is the same, then your top speed will be the same; all that would change would be your acceleration: In each gear you have a range where power is at it's highest. Below this gear speed your power is low (have you ever tried to accelerate in 5th from stationary?) And above it you hit the speed ...


10

The range switch doesn't think the car is in park. On Fords theres an adjustable cable if you look on the driver side of the transmission there will be lever with a cable attached. Sometimes the clip on the cable fails. if the cable is OK pull the lever all the way into park and it should start. If it doesn't you probably need a new range switch.


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