LEGO gears are an essential part of many LEGO Technic and Great Ball Contraption (GBC) creations, allowing builders to transmit power and motion between different parts of their models. In this article, we’ll cover the basics of using all types of LEGO gears, including bevel gears, worm gears, gear rack and gearboxes as well as how to calculate gear ratios and some tips for using gears effectively in your builds.

But what is a gear by definition? We took this straight from our Terminology page:
Gear: A rotating circular part with cut teeth on the outer circle. The cut teeth allow a gear to mesh with another gear to transmit torque. Gears of different sizes can change the speed, torque, and direction of a power source. Normally the teeth on the two meshing gears should have the same shape. However with LEGO more combinations are possible. See also Gear ratio and Gearbox.

 

 

Types of LEGO Gears

LEGO gears come in a variety of sizes and styles, each with its own specific use and function. Here are some of the most common types of LEGO gears:

• 8 tooth gears: These are the smallest gears available, and are often used for fine adjustments or for creating a high gear ratio.
• 16 tooth gears: These gears are slightly larger than 8 tooth gears, and are often used for moderate gear ratios or for connecting to other gears with a small number of teeth.
• 24 tooth gears: These gears are a good size for most general-purpose applications, and are often used as the main drive gears in LEGO Technic and GBC creations.
• 40 tooth gears: These are the largest gears available, and are often used for low gear ratios or for transmitting power over long distances.

There are even more sizes available but next to this there are also many different shapes available. we will discuss the most common type of LEGO gear shapes:

 

Bevel Gears
Bevel gears are gears that are designed to transmit power at an angle, rather than along a straight line. They are typically used to transmit power between two shafts that are at a right angle to each other. Bevel gears can be either straight or spiral, and are available in various sizes and tooth counts.
Our GBC 40 Tippy Tilt Trays use many bevel gears to transmit the power over a long distance.
Get the building instructions of the GBC 40 Tippy Tilt Trays

 

 

 

 

 

 

Worm Gears
Worm gears are a type of gear that consists of a helical screw (the worm) that meshes with a toothed gear (the worm gear). Worm gears are typically used to transmit power at a 90-degree angle, and can also be used to increase or decrease torque. They are especially useful in situations where high reduction ratios are needed, as a single turn of the worm can result in several turns of the worm gear.
The 3 wings in our GBC 17 Wing Lift have to move slowly to enable the GBC Ball to roll over them. We accomplished this by using a worm gear which got us a gear reduction of 8 to 1. An extra advantage we got it that the direction of the rotation changed which allowed us to easily attach levers to the side. The main drive shaft can in this way drive all the 3 wings perfectly in sync.

Get the building instructions of the GBC 17 Wing Lift

 

 

 

 

Gear Racks
Gear racks are straight, toothed bars that are used in conjunction with spur gears to convert rotary motion into linear motion (and vice versa). Gear racks are often used in LEGO Technic and GBC creations to lift or move objects along a straight path.
Our Full Automatic Elevator Module in our GBC 30 Fun Park uses gear racks to lift the GBC Balls up. In combination with a gearbox we have automated it so the lift automatically goes down in a controlled way using again the gear racks.

Get the building instructions of the GBC 30 Fun Park

 

 

 

 

 

Gearboxes
A gearbox is a mechanical device that is used to transmit power and torque between two or more rotating shafts. In a LEGO GBC, a gearbox is typically used to increase or decrease the speed or torque of a motor, or to transmit power at an angle. Gearboxes can be either manual (operated by hand) or automatic (operated by a motor or other power source).
In our GBC 21 Mine Factory we used an automatic operated gearbox to change the direction of the Rotating Dual Output Pump. As a bonus there is also the option to manually control this by hand.

Get the building instructions of the GBC 21 Mine Factory

 

 

 

 

 

Differentials
A differential is a mechanical device that is used to transmit power from a drive source to two or more driven outputs. In a vehicle, a differential allows the wheels on either side of the vehicle to rotate at different speeds, which is necessary for turning and maneuvering. LEGO differentials are commonly used in LEGO Technic and Great Ball Contraption (GBC) creations to transmit power or as an ingenious timings mechanism for precise control. More on that in another Mechanical Monday.

 

 

 

 

 

 

Turn Tables
LEGO turntables, also known as LEGO Technic Rotational Joints, are a type of LEGO piece that allows for movement in LEGO models. They consist of a circular base with a central axle, and are designed to rotate around this axle. Due to the fact that there is a 3×3 stud hole in the middle, it allows other axles to go through, making even more complex machines possible. LEGO turntables can also be used as big gears, and when in combination with a smaller gear it creates a big gear ratio which can be used to slow down a machine. We have also done this to slow down the mechanism of our GBC 49 Geneva Drive.

Get the building instructions of the GBC 49 Geneva Drive

 

 

 

 

 

Calculating Gear Ratios

The gear ratio is the relationship between the number of teeth on two gears, and determines how much faster or slower one gear will rotate compared to the other. To calculate the gear ratio, simply divide the number of teeth on the driving gear (the gear that is providing the power) by the number of teeth on the driven gear (the gear that is receiving the power). For example, if a 24 tooth gear is driving a 40 tooth gear, the gear ratio would be 0.6 (24 / 40).

We often use this handy calculator to get many gear ratios quickly: Gear Calculator

 

Using Gears Effectively

Here are a few tips for using gears effectively in your LEGO Technic and GBC creations. Most important is to understand their use and when to implement them.

• Use the appropriate size gear for the job: Smaller gears are more precise, but can’t handle as much torque as larger gears. Larger gears are less precise, but can transmit more power.
• Consider the gear ratio: A high gear ratio (e.g. 8:1) will result in slower but more powerful movement, while a low gear ratio (e.g. 1:8) will result in faster but less powerful movement.
• Use multiple gears to fine-tune the gear ratio: By using a combination of gears with different numbers of teeth, you can fine-tune the gear ratio to get the exact movement you want.
• Use gears to transmit power over long distances: By using gears with a low gear ratio (e.g. 1:8), you can transmit power over a long distance without losing too much torque.
• Experiment with different gear combinations: LEGO Technic and GBC creations often have multiple gear trains, and finding the right combination of gears can be a trial and error process. Don’t be afraid to try out different gear combinations to see what works best for your creation.
• Change the rotation direction by using 2 gears. You can even use different gear rations to change the output speed as well.
• Worm gears can be useful in situations where you need to transmit power at a 90-degree angle or where you need to increase torque. Due to the physical shape it will also block the rotation of the output axle which makes for strong mechanism when implemented properly.
• Use bevel gears to transmit power at an angle: Bevel gears can be used to transmit power between two shafts that are at a right angle to each other.
• Use gear racks to convert rotary motion into linear motion: Gear racks can be used in conjunction with spur gears to convert rotary motion into linear motion, allowing you to lift or move objects along a straight path.
• Use gearboxes to increase or decrease speed or torque, or to transmit power at an angle: Gearboxes can be used to change the speed or torque of a motor, or to transmit power at an angle.

 

 

Hopefully this article has helped you understand the basics of using all types of LEGO gears in your creations. With a little practice, you’ll be able to create all kinds of intricate and sophisticated mechanisms using these versatile little pieces in your next big LEGO Technic machine. Keep on bricking and have fun!