Why do transmissions have different gear ratios?
Gear ratios can be boiled down to a single statement: Higher ratios (with a lower numerical value) give better torque/acceleration and lower ratios allow for higher top speeds and better fuel economy. Higher ratios mean the engine has to run faster to achieve a given speed.
What is the purpose of using multiple gears in a transmission?
The transmittable torque can be increased using additional planetary gears when doing this. The direction of rotation of the drive shaft and the output shaft is always the same, provided that the ring gear or housing is fixed.
How does gear ratio affect transmission?
The final drive ratio is the last bit of gearing between your transmission and the driven wheels. In general, a lower final drive ratio will lead to less torque at the wheels but a higher top speed. Meanwhile, a higher ratio will result in the opposite, i.e. more torque at the wheels but a lower top speed.
Why are overdrive gear ratios used in most modern transmissions?
Generally speaking, overdrive is the highest gear in the transmission. Overdrive allows the engine to operate at a lower RPM for a given road speed. This allows the vehicle to achieve better fuel efficiency, and often quieter operation on the highway.
What gear ratio is best for torque?
A numerically higher axle ratio provides a mechanical advantage to send more of the engine’s available torque to the rear tires (and front tires, in a four-wheel drive vehicle), but you pay the price at the fuel pump. So, a truck with optional 3.73 gears will tow a heavier trailer than one with 3.55 or 3.21.
Why are there so many gears in a transmission?
The way different transmissions are built varies greatly, but the basic concept of gears and gear ratios is the same throughout. That sounds great, but there is a trade off. It is much harder to turn the wheel at a 2:1 ratio than it is at a 1:1 ratio.
Why do rear ends and differentials have gear ratios?
Transmissions and rear ends/differentials both have gear ratios. Transmissions use gear ratios to keep your engine within a safe and economical operating RPM range, while giving your vehicle the ability to accelerate to and maintain a safe speed across the ground.
What are the gear ratios in a truck?
Gear ratios are what engineers call “torque multipliers.” Higher numbers give more torque more quickly to allow better acceleration. Let’s compare that to, say, an early 1960s Ford truck transmission, with fourth gear at a 1:1 ratio, third at 1.69:1, second at 3.09:1 and first at a very short 6.32:1.
How is the torque produced in a transmission?
Inside the transmission are a series of variously sized, toothed gears that produce torque. Because the gears that interact with each other are different sizes, torque can be increased or decreased without changing the speed of the engine’s rotational power all that much. This is thanks to gear ratios.