IB Design Technology Topic A3.3.6 Gear Systems Revision Notes (HL)

IB Design Technology Topic A3.3.6 Gear Systems Revision Notes (HL) | RevisionDojo

Written by official IB examiners

Gears: Teeth That Trade Speed for Torque

Definition

Gear

A toothed wheel that meshes with another to transmit motion or change speed/direction.

Gears transmit rotary motion from one shaft to another through interlocking teeth, so they never slip the way a belt can.
Because the teeth mesh, the two wheels are locked together, and that is what makes a gear train predictable.

The Parts of a Gear

Gear teeth: the interlocking projections that engage with the next gear.
Gear shaft: the axis the gear turns around.
Pitch circle: the imaginary circle where the teeth actually engage, which sets the effective size of the gear.
Module: the pitch diameter divided by the number of teeth, and two gears must share a module to mesh at all.
Pressure angle: the angle of the tooth face, which affects how smoothly and how strongly the drive runs.

Note

The module is the parameter that decides whether two gears are compatible.
Two gears with different modules cannot mesh, no matter how many teeth each one has.

Gear Ratio: The Bargain Every Gear Train Makes

The gear ratio compares the teeth on the driven gear with the teeth on the driver gear, and it decides everything the train does.
A small gear driving a large one reduces speed and increases torque, which is what you want climbing a hill.
A large gear driving a small one increases speed and reduces torque, which is what you want on the flat.
Two meshing gears also turn in opposite directions, which is a fact examiners like to test.

Note

$$\text{Gear Ratio} = \frac{\text{Teeth on Driven Gear}}{\text{Teeth on Driver Gear}}$$
A high ratio such as 3:1 means more torque and less speed.
A low ratio such as 1:3 means more speed and less torque.
Calculating gear ratios and output speeds is developed in B3.3.

The Seven Types of Gear

Each type exists to solve a problem the plain spur gear cannot.
As you read, note what each one does to the axis of rotation, because that is usually the reason it exists.

Spur Gears

Definition

Spur Gear

A toothed gear with teeth that project parallel to the gear’s axis, used to transmit motion between parallel shafts.

Use: transmit motion between parallel shafts.

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Note

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Gears: Teeth That Trade Speed for Torque

Definition

Gear

A toothed wheel that meshes with another to transmit motion or change speed/direction.

Gears transmit rotary motion from one shaft to another through interlocking teeth, so they never slip the way a belt can.
Because the teeth mesh, the two wheels are locked together, and that is what makes a gear train predictable.

The Parts of a Gear

Gear teeth: the interlocking projections that engage with the next gear.
Gear shaft: the axis the gear turns around.
Pitch circle: the imaginary circle where the teeth actually engage, which sets the effective size of the gear.
Module: the pitch diameter divided by the number of teeth, and two gears must share a module to mesh at all.
Pressure angle: the angle of the tooth face, which affects how smoothly and how strongly the drive runs.

Note

The module is the parameter that decides whether two gears are compatible.
Two gears with different modules cannot mesh, no matter how many teeth each one has.

Gear Ratio: The Bargain Every Gear Train Makes

The gear ratio compares the teeth on the driven gear with the teeth on the driver gear, and it decides everything the train does.
A small gear driving a large one reduces speed and increases torque, which is what you want climbing a hill.
A large gear driving a small one increases speed and reduces torque, which is what you want on the flat.
Two meshing gears also turn in opposite directions, which is a fact examiners like to test.

Note

$$\text{Gear Ratio} = \frac{\text{Teeth on Driven Gear}}{\text{Teeth on Driver Gear}}$$
A high ratio such as 3:1 means more torque and less speed.
A low ratio such as 1:3 means more speed and less torque.
Calculating gear ratios and output speeds is developed in B3.3.

The Seven Types of Gear

Each type exists to solve a problem the plain spur gear cannot.
As you read, note what each one does to the axis of rotation, because that is usually the reason it exists.

Spur Gears

Definition

Spur Gear

A toothed gear with teeth that project parallel to the gear’s axis, used to transmit motion between parallel shafts.

Use: transmit motion between parallel shafts.

Definition

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(on a website) an arrangement whereby access is restricted to users who have paid to subscribe to the site.

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Tip

Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

A. Design in theory8 subtopics

B. Design in practice8 subtopics

C. Design in context8 subtopics

IB Design Technology Topic A3.3.6: Gear Systems Notes

Gears: Teeth That Trade Speed for Torque

The Parts of a Gear

Gear Ratio: The Bargain Every Gear Train Makes

The Seven Types of Gear

Spur Gears

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Duis aute irure dolor in reprehenderit

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Unlock the rest of this chapter with a free account

Gears: Teeth That Trade Speed for Torque

The Parts of a Gear

Gear Ratio: The Bargain Every Gear Train Makes

The Seven Types of Gear

Spur Gears

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account

A. Design in theory8 subtopics

B. Design in practice8 subtopics

C. Design in context8 subtopics