Transmission and Drivetrain flashcards

$\text{ratio}=\frac{n_{in}}{n_{out}}=\frac{N_{driven}}{N_{driving}}$. A 12-tooth driving gear turning a 36-tooth driven gear is 3:1; output speed = input speed divided by the ratio.

$T_{out}=T_{in}\times \text{ratio}\times \eta$ ($\eta$ as a decimal). 150 N$\cdot$m through 2.5:1 at 90% gives 337.5 N$\cdot$m. Apply efficiency to torque or power, never to speed.

Above 1 (e.g. 3.5:1) is a reduction: slower output, more torque. Exactly 1:1 is direct drive. Below 1 (e.g. 0.7:1) is overdrive: faster output, less torque.

Multiply, never add: $R_{overall}=R_{trans}\times R_{final}$ (times any transfer-case ratio). 2.8:1 with a 3.5:1 final drive gives 9.8:1, not 6.3:1.

Placed between two gears, it makes the output turn the same direction as the input (as in reverse). Its tooth count cancels out, so it does not change the overall ratio.

$n_c=\frac{n_L+n_R}{2}$: carrier speed is the average of the axle speeds. If one wheel is held still, the other spins at twice carrier speed.

A clutch is a pedal-operated friction device (flywheel, friction disc, pressure plate) that connects or disconnects engine torque. A torque converter is a fluid coupling (impeller, turbine, stator) that slips and can multiply torque.

A synchronizer uses a friction cone to match gear and shaft speeds so a manual shift engages without grinding. A transfer case splits power to front and rear driveshafts in 4WD and may add a low range.