why do most cars with automatic transmissions have lower gears since we only use them for pulling things we do not pull? would it not be easier for only 2 foward gears, low and high! and who pulls with a car anyway?
I’ll answer the question “why do automatic transmissions have multiple gear ranges” it keeps the engine in it’s most efficient range.
There are CVT transmissions (limited in amount of power they can operate with)
In eary auto trans days we did only have 2 forward ranges (powerglide)
It’s has turned into a favorite (modified) in some drag racing classes.
We do get posts from overseas about people towing with their passenger cars,some people do it.
Yea, it would be easier to make a two speed auto. Many of the early models were two speed. However modern three and four speed transmissions can better match the speed of the engine to the task being demanded by the driver. The result is better performance and mileage. Modern cars shift very smoothly and are reliable so it is not a problem to have more gears.
A two speed automatic transmission would not allow your car to achieve gas mileage as good as it can get with a 4 or 5 speed transmission. Additionally, your car will accelerate faster with additional gears.
A typical old-style 2-speed automatic would shift into high gear at 45 mph or so. When accelerating at higher speeds, no lower gear was available to the driver, and he/she had to accelerate in high gear, which produced fairly pathetic acceleration.
Trust me–you wouldn’t want to go back to the days of 2-speed transmissions.
Agreed. I owned a 59 Chevy Impala with a Powerglide and in normal driving it would wind on out speed-wise until banging into high gear at 40 MPH.
For racing they’re neat though.
Many people pull with a car. I’ve done it a million times and with many cars they’re no different than a truck or SUV. Same engines, transmissions, rear ends, etc.; just a difference in sheet metal and occassionally rear end gear ratio.
Think Crown Vic and Ford F150.
The Powerglide in my Chevelle would kick in as low as 25 MPH. When going through residential areas with lots of stop signs, I’d just drop it into low gear and cruise slowly through the area to save on the constant shifting it’d be doing otherwise
A retired friend with too much free time on his hands replaced the fire damaged motor of his wife’s older Jaguar sedan with a Chevy 6/ 2 speed powerglide combination and felt he couldn’t get a more dependable drive train. His wife, a purist, now refuses to set foot in the car. The price of reliability or maybe that was the plan all time.
Also… engine braking with a 2 speed was a miserable proposition above 40 mph.
They have 4 or 5 forward gears for the same reason a manual has.
The lower gears you see next to the “D” indicator are for instances where you might want to keep the vehicle in a lower gear. They are not for pulling things. If you tow with an automatic transmission, you should do it in drive (D) with the overdrive disengaged if the vehicle is so equipped. The lower gears you speak of on the shift indicator are for very specific circumstances where you might want to control what gear you are in, like when you are going down a long steep hill and you want do downshift to control your speed, or you’re stuck in the mud and want to keep it in the lowest gear as you try to rock the vehicle out of the hole created with your drive wheels.
The answer to your other questions are:
-If you only had two forward gears, how would you downshift to control your speed when going down a long steep hill? Your brakes would overheat.
-Lots of people tow with cars. Old police cruisers are perfect for small camper trailers. Lots of people buy minivans and cars with larger engines for light towing. There are several small camper trailers like this one http://www.tab-rv.com/story/index.php that can be towed with a car. There are also many small pop-up trailers that can be towed with a car. You can also tow a small U-Haul trailer with a car if you don’t overload it. I have personally towed with a 1989 Nissan Maxima, a 1996 Ford Taurus wagon, and a 2002 Toyota Sienna minivan. As long as you don’t exceed the towing capacity and the maximum tongue weight of these vehicles, they are perfectly adequate for towing.
Here are a couple examples of cars that can be used for towing.
We may eventually go back to one or two speeds…if the Tesla works out.
Mercedes, on the other hand, is up to what, 8 or 9 speeds?
Downshifting when going down a mountain. The brakes will not survive down a mountain slope.
The 2 range on Ford products is great for starting to move on ice. It doesn’t work on GM or Chysler.
Keeping control on rough ground.
Getting a stuck car out of mud or snow.
Many of the city buses of the late 1940’s through the 1960’s had a 2 speed automatic transmission. The driver could select Drive, Neutral, or Reverse. There was always a jolt when the transmission shifted into high range.
One of the worst transmissions, IMHO was the Chrysler automatic called Gyro-matic in the Dodge, tip-toe shift in the DeSoto, and Presto-matic in the Chrysler. The transmission was coupled to the engine through a clutch and a fluid coupling (no torque multiplication) The normal driving range had two forward speeds and one acclerated to 15-20 mph,then released the accelerator and with a clunk, the transmission went into high range. There was a manually selected low range with two speeds as well, but one could not conveniently go through all 4 speeds starting from rest. If you drove one of these, you would immediately see the need for more speeds in an automatic transmission.
In the late 1940’s through the 1960’s,there were two different schools of thought within General Motors about how the automatic transmission should function. The hydramatic used by Pontiac, Oldsmobile and Cadillac had 4 forward speeds and a fluid coupling (no torque multiplication) between the engine and transmission. The PowerGlide automatic originally depended completely on the torque converter as did the Buick Dynaflow when the normal Drive range was selected. Both of these transmissions had a manually selected low range. In 1953, Chevrolet modified the PowerGlide so that it would start in the low range and then automatically go into direct drive. The Chrysler fully automatic transmission, called PowerFlyte, introduced in 1954, only had two forward speeds. In 1957, Chrysler introduced the Torqueflyte, which had three forward speeds and was quite an improvement over the Powerflyte.
If you had driven cars in this time period as I did with the 2 forward gears, you would understand why we have 4 or more speeds in today’s automatic transmissions. I could shift gears more smoothly in a standard transmission car than I could drive a 2 speed automatic that really jerked between low and high.
It looks like a tent on wheels
On my nissan Maxima 1996, should i drive with the over drive light on or off?
I dispute the claim about Overdrive. You can tow in overdrive, and should tow in overdrive at the appropriate speeds, but you don’t want to have the transmission hunting between Drive/Overdrive. If you are heading down a flat boring highway at 70 MPH, it’s best done in Overdrive.
If you are cruising up/down hills or grades or flirting with 40-50 MPH, the tranny is going to hunt between D/OD, and then it’s time to lockout OD, or just select D.