Basically, the 3 2 1 gears are limiting how far through the gears your car can go. If you select the "1" option, the gearbox will only use first gear. If you select the "2" option, the gearbox will only use first and second gear. If you select "D", the gearbox will use all of the gears available.
L = Low gear or first gear. Your car will not shift out of first. 2 = Second Gear, your car will not shift above second. 3 = Third Gear, Your car will not shift above third. OD = Overdrive - a highway gear, on a standard 3 speed transmission this would be 4th.
L/Low – Driving slowly on steep hills. Second – Driving on steep hills at a steady pace (somewhat faster than Low) Third – For cruising at a slow and steady pace, especially while towing or in bad weather.
It means that when you are going down a long hill with 50–60mph speed limit you should use 3 to slow the truck without overheating the brakes. When you're going down a wide mountain road at 30–40mph you should use 2 to slow the truck without overheating the brakes.
Basically, the 3 2 1 gears are limiting how far through the gears your car can go. If you select the "1" option, the gearbox will only use first gear. If you select the "2" option, the gearbox will only use first and second gear. If you select "D", the gearbox will use all of the gears available.
The numbers relate to the number of times the driveshaft has to rotate to make the driven wheels make a full rotation. It's written out with the driveshaft rotation first and then the wheel rotation, the latter of which is always 1. So, for example, you could see a truck's axle ratio expressed as 3.21:1 or just 3.21.
Yeah, it's probably fine. When towing things, you usually put it in third to prevent rapid shifting between third and fourth, but it's still fine to drive the speed limit in most places. A bit of gas millage loss, but other than that, you're fine.
As the name suggests, the D3 (or sometimes just 3) mode will only utilize the first 3 gear ratios of your car, or in some, locks it on the 3rd gear only. Just like the 2 and L, it will shift at a higher gear if the maximum RPM has been reached. It will also maximize the RPM range per gear for the needed power and pull.
There are factory 3-Speed Transmissions capable of Highway Speed (55–80 MPH) in 3rd Gear. There are also 6-speed transmissions capable of those speeds in 1st or 2nd Gear.
But if you put it in “3,” it will lock out fourth gear. If you put it in “2,” it will lock out both third and fourth gears. And if you put it in “1,” it will only operate in first gear. Most drivers, however, leave the lever in “D” all the time.
What is a Car's High Gear? The fifth gear, or sixth if one is available, is the highest gear in a manual car. However, not all manual cars have a sixth gear. When a car is automatic, the gearbox often chooses the highest gear based on the speed of the car.
Things You Should Know
Move the shifter from P (park) to D (drive) if you want to go forward, or R (reverse) if you want to go backward. Leave the car in D (drive) while moving forward.
Most automatics also allow you to manually select one or more lower gears, such as Low (L), 1st (1) and 2nd (2). In the case of L and 1, the transmission will stay in the lowest gear and not shift on its own. That allows maximum power when you need it, such as on a steep hill, but greatly limits your speed.
Uphill: Approach uphill situations with an appropriate amount of momentum, a higher gear (3rd in an automatic transmission) and less throttle to reduce torque, which also reduces wheel spin. The last thing you want to do is get halfway up the hill, lose traction and begin to spin your wheels.
We can also write this as 3/2 or 1.5 : 1, etc. What this gear ratio means is that the smaller driver gear must turn one and a half times to get the larger driven gear to make one complete turn. This makes sense — since the driven gear is bigger, it will turn more slowly.
Under normal driving conditions, it is usually best to use the “D” gear selection rather than D3. D3 is not ideal for normal highway driving, as the engine will have a higher RPM at the lower gears and consume more fuel.
Can i shift my automatic transmission from D to 3, 2 or 1 without stopping the car? Yes you can. It's handy for towing and steep hills. Assuming you're talking about an automatic/standard, all it does is limit the highest gear it'll use.
Yes, you can do so but you need to have sufficient speed of the output shaft (drive shaft) for the vehicle to not stall.
Avoid changing gears while the car is moving
The car will actually stop but you will end up wearing out your automatic transmission band. The transmission band is hard to access making its repair and replacement expensive and time-consuming.
Things You Should Not Do With Automatic Transmission Vehicle: Never Use Two Feet When Driving An Automatic Car. Never Switch To 'Park' Before An Automatic Car Stops Completely. Never Drive An Automatic Car Downhill While On Neutral.
For flat places, a ratio of 2.6 to 3.0 is ideal for most people. The lower value of this range, with a cadence of 90 rpm, will allow us to ride around 30km/h, while the upper, 34km/h. If you're just starting out on your adventure on a single speed or fixed gear bike, a gear ratio of around 2.7-2.8 will be ideal.
Between 25% and 50%: A gearing ratio within this range is typically considered optimal or normal for well-established companies.
The most popular rear end ratio in trucks today is the 3:55, which sort of averages towing power and fuel economy. This is a good ratio for the occasional towing or hauling individual. For a person who tows more often, and heavier loads, the 3:73 or 4:10 may be more appropriate.