Mechanical Engineers, Learn Gear Drives | Yakh'iFuture

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Gear Drive

Gear drives are used in machines of all kinds to change the speed, force, rotational direction or movement of machine parts. In cars, they are used in the gearbox to help control the amount of power and speed transferred from the engine to the wheels.

Low gears provide the most pulling power, but also the lowest speed, for when the car needs to do things like go up a hill. Higher gears have more speed, but less power.

Depending on their intended purpose, gears vary in size and shape. If you go from a big gear with many teeth, to a smaller gear with less teeth, you're increasing the speed of the machine part you're transferring power to. If you turn the gears in the opposite direction, and transfer power from the small gear, to the larger one, you're decreasing speed, but increasing the force.

In order to do this, gears turn opposite directions, and "mesh" with interlocking teeth. Because of this, there is no slippage, and gears can withstand high strain torque. They're less likely to fail, but if they break, they're not repairable. They're also expensive to make, and need constant lubrication.

Test it out

Tap the diagram for more information and click on the buttons to change a component and see what happens!

Increase Driving Power
Switch Driving Gear
Add Idle Gear

Example calculations

In order to work with Gear Drives, mechanical engineers need to understand and work with a variety of calculations. Here are just a few:

Centre Distance (C):

C = \frac{PCD_a + PCD_e}{2}

Module (m):

m = \frac{PCD}{T}

Circular Pitch (CP):

CP = \pi \times m

Gear Ratio (R):

R = \frac{T_2}{T_1}

You can also calculate gear ratio using angular velocity, gear speed or diameter:

R = \frac{\omega_1}{\omega_2} = \frac{n_1}{n_2} = \frac{d_2}{d_1} = \frac{T_2}{T_1}

Pressure Angle	$\alpha$
Centre Distance	$C$
Circular Pitch	$CP$
Pitch Circle Diameter	$PCD$
Dedendum (Root) Diameter	$D_e$
Addendum (Tip) Diameter	$D_a$
Module	$m$
Teeth	$T$

Gear drives are used in machines of all kinds to change the speed, force, rotational direction or movement of machine parts. In cars, they are used in the gearbox to help control the amount of power and speed transferred from the engine to the wheels.

Low gears provide the most pulling power, but also the lowest speed, for when the car needs to do things like go up a hill. Higher gears have more speed, but less power.

Depending on their intended purpose, gears vary in size and shape. If you go from a big gear with many teeth, to a smaller gear with less teeth, you're increasing the speed of the machine part you're transferring power to. If you turn the gears in the opposite direction, and transfer power from the small gear, to the larger one, you're decreasing speed, but increasing the force.

In order to do this, gears turn opposite directions, and "mesh" with interlocking teeth. Because of this, there is no slippage, and gears can withstand high strain torque. They're less likely to fail, but if they break, they're not repairable. They're also expensive to make, and need constant lubrication.