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in simplest terms, gear ratio is all about leverage
the same concept that makes a larger lever able to apply more force while moving a longer distance applies to gears. instead of comparing the length of the lever, you compare the size of the gears or number of teeth (which is the same as a measure of size if teeth are the same size since we are looking for a ratio or fraction)
the size of one gear in relation to the other is a "gear ratio". if gear A has 40 teeth and gear B has 10 teeth, the ratio is 4:1.
for gear A to go a complete revolution it went through 40 teeth, and if gear B went for a complete revolution it went through 10. what does this mean? it means if they are paired together--let's say gear A turning gear B--then for every turn of A, gear B turns 4 times.
how does this relate to speed and torque? well in the scenario above, gear B is turning 4 times as fast as gear A but with 1/4 of the torque or turning force (of course there are factors that influence this and there is more to it, but let's keep it simple to explain the relationship).
this is easiest to see/understand in a bicycle. when you small gear in back (wheel) versus a large gear, pedaling is "harder". the smaller the gear, the more the end of the wheel has leverage over it, however the smaller the gear, the less pedaling it takes to turn the wheel a full turn.... if you go to a larger gear in back it will take more pedals to turn the wheel but feel easier because you have increased your mechanical advantage on the ground.
in an automotive transmission, the input of the transmission can be equated to engine RPM (for this example) and the output can be equated to wheel speed (in this example), in 1st gear the output gear is larger than the input gear. this means that the wheels will turn less than the engine.... you will go 'slow' even with high RPM but you have more torque so you can start the car from a stop or go up a hill.... in the highest gear the output gear is smaller than the input, this means that for every turn of the engine the wheels will turn several times (this is called overdrive)... once you are already moving at a high speed you don't need as much TORQUE to keep the car going so you sacrifice torque in higher gears to gain speed and keep your engine RPM down.
if you are asking in regards to a differential gear ratio (like performance vs. stock) it's the same idea. the differential is just another gearset, like in the transmission, but this one can't be shifted. so if you have a differential that's lower geared you will have more torque at any given RPM but to go at a given speed your engine will have to turn faster than with a higher geared differential. in theory this will lower your top speed.
if you go with a higher gearset you will have less torque in any given gear, but will have a higher speed at any given engine RPM vs the lower geared set. -Ramsey Mesyef
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∙ 15y ago
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What happens to torque when something rotates faster?
When ever you attach a gear with less teeth to a gear with more teeth, thus increasing your gear ratio and the speed in which the gear with less teeth rotate, the amount of torque in your gear combination decreases. This can also be expressed as a ratio, which happens to be the inverse of a gear ratio, meaning if your gear ratio was lets say... 1:5, the ratio for the amount of torque is 5:1, meaning you receive five times less the amount of torque, to increase your speed five times as fast.
When you use a gear with a small diameter to drive a gear with a large diameter what is increased speed or torque?
Torque is increased on the larger, driven gear. The increase can be calculated as the ratio of the radii of the two gears. For example, if the small gear has a radius of 2 cm and the larger gear has a radius of 10 cm, the torque ratio is 10/2 (ten to two), or 5/1 (five to one). So the driven gear is producing 5 times the torque of the driving gear. The speed ratio is the reverse; the driven gear is rotating at 1/5 the speed of the driving gear.
How do you use gear ratio to increase horsepower?
It doesn't work that way. The gear ratio determines what speed the vehicle is running at when in the (torque) powerband.
How the speed of a vehicle is related to engine speed and how tha vehicle speed is affected by the engine torque and gear ratio?
A smaller number as a gear ratio means more speed. Higher ratios have higher torque and less speed. The size of the engine just determines hp and tq for that engine unless it is upgraded. The gear ratio and engine determine the vehicles top speed and acceleration. More torque means more power therefore more acceleration.
How do you control torque?
In case of Bikes: By increasing the gear ratio from the main transmission point. As the torque and speed ratio is inversely proportional so increasing the teeths of the rear end gear to the main engine gear will increase the torque simultaneously it will also reduce the pick up
How do you control engine torque?
In case of Bikes: By increasing the gear ratio from the main transmission point. As the torque and speed ratio is inversely proportional so increasing the teeths of the rear end gear to the main engine gear will increase the torque simultaneously it will also reduce the pick up
What is better a high gear ratio or a low gear ratio?
It depends on what you need - if you want lots of speed no power on the bottom end you go with the high ratio - if you want lots of torque on take off and lots of pulling power you take the low gear ratio.
What gear ratio would you use to get enough torque and speed to achieve that fastest time?
The gear ratio for top gear is chosen to produce maximum speed, which occurs at a speed where the engine's maximum power is take up with maintaining a constant speed (on the level). For cars the overall ratio for top gear is 3.5 to 4.5 : 1. For example, if the engine's maximum power is 100 bhp at 6300 rpm, and that power can drive the car at the maximum speed of 110 mph, the overall ratio is chosen to give 6300 rpm at 110 mph.
Why is gear ratio also called velocity ratio?
The gear ratio of a train, also known as its speed ratio, is the ratio of the angular velocity of the input gear to the velocity of the output gear. The gear ratio is very important when it comes to physics.
In a semi truck will you get higher torque and less road speed with a higher gear ratio?
"Higher" can be a pretty ambiguous term here. Generally speaking, for higher torque and lower road speeds, you'd have taller rear end gear ratios.
What causes incorrect gear ratio in a VW Touareg?
Mechanical failures causes incorrect gear ratio in the VW Touareg. Lots of torque is what causes the incorrect gear ratio in VW Touareg.
Does a bad speed sensor effect the gear ratio?
No, the gear ratio is determined by the number of teeth in the ring gear and pinion gear. To be changed, that would require a physical alteration, which a speed sensor cannot do.
