Engineering · Lesson 02

Mechanisms and Gear Systems

This lab makes the Golden Rule of Mechanics visible: if you want more turning force, you must give up speed. Configure a live transmission, watch the gears mesh tooth-by-tooth, and decide whether your system should favor velocity or torque to lift a heavy crate safely.

Mechanical advantage Gear ratios Torque vs speed Industrial lift lab

Mission brief

Lift the clinic supply crate

A motor can only deliver a limited amount of input torque. Your job is to choose a driver gear and a driven gear that create enough mechanical advantage to hoist the load, but not so much output speed that the crate slams upward and destabilizes the system.

Motor 420 Nm Available input torque from the motor shaft

Motor speed 120 rpm Input shaft rotation before the gear reduction

Target Lift safely Output torque must beat the crate load without overspeeding the winch

Trade-off No free lunch More torque means less speed. More speed means less torque.

What gears actually do

Gears do not create energy out of nowhere. They redistribute it. A small driver gear pushing a larger driven gear makes the output spin more slowly, but with greater torque. Reverse that pairing and the system spins faster, but the lifting force drops. That trade is the heart of mechanical advantage.

Driver gear The motor gear is the input. Its tooth count sets how much leverage it has over the next gear.

Driven gear The output gear receives motion. A larger driven gear increases torque and lowers rpm.

Opposite rotation Two meshed gears always rotate in opposite directions. The lab visualizes that sign flip directly.

Mechanical advantage When the ratio grows above 1:1, the output gains force while sacrificing speed. That is what lets a machine lift heavier loads.

Transmission lab

Mechanical Advantage Studio

Tune the driver, driven, and crate load. Then engage the motor and watch whether the transmission stalls, lifts cleanly, or hoists too fast and crashes the payload.

System ready

Golden rule monitor Right now the system is balanced. Change the tooth counts and the live gauges will show how power shifts between speed and torque.

Load challenge 500 kg crate on a 0.18 m winch drum

Build a reduction gear if the motor keeps stalling. Build a faster ratio only if you can still lift the crate without overspeeding the winch. Torque and speed balanced

Configuration

Every adjustment updates the simulation and the math in real time.

Driver gear 20T

Smaller driver gears increase the ratio when they power a larger output gear.

Driven gear 28T

Larger driven gears boost torque but slow the output shaft and winch.

Crate load 500 kg

Heavier crates require more output torque. If your ratio is too aggressive toward speed, the motor will stall.

Balance meter

Velocity Torque

Output torque 1.29x

Output speed 0.71x

Live ratio math

28 ÷ 20 = 1.40 : 1

Gear ratio = Teeth out / Teeth in

Output torque = Input torque × ratio × efficiency

Output speed = Input speed ÷ ratio

Why this works

The lab uses a real ratio relationship. If the output gear has more teeth, it turns more slowly and gains torque. If the input gear is larger than the output gear, the winch gets faster but weaker.

A ratio above 1.00 : 1 is a reduction. That favors force over speed.
A ratio below 1.00 : 1 is a speed-up train. That favors rpm over lifting power.
If the output torque is lower than the required drum torque, the motor stalls and the crate stays put.
If the winch rpm climbs too high, the crate lifts unsafely fast and the system fails even if the torque is sufficient.

Output torque 541 Nm Turning force available at the driven gear after the ratio and efficiency are applied.

Required torque 883 Nm The drum needs this much torque to lift the crate against gravity.

Output speed 86 rpm Fast systems lift quicker, but too much speed makes the hoist unstable.

Mechanical verdict Undersized The motor is currently short on torque. Increase the reduction ratio to gain lifting force.

Design sequence

Machine design is usually a loop: define the job, estimate the force, choose a mechanism, and check the trade-offs. The same loop is happening inside this lesson.

1. Estimate the load Start by asking how much force the machine needs to move the object at all.

2. Choose the ratio Match the gear sizes so the output shaft has the right balance of torque and rpm.

3. Check the motion Even a strong design can fail if it moves too fast for the task or for the material being handled.

4. Retune the system If the machine stalls or overspeeds, adjust the ratio and test again until the mechanism matches the job.

Quick design tips

If your hoist keeps failing, these are the first levers to pull.

Use a small driver for heavy loads A smaller input gear powering a larger output gear is the classic way to gain torque.

Watch the balance meter If the needle stays far to the left, you are chasing speed. The motor will likely run out of lifting force.

Do not ignore safe speed A ratio can be “strong enough” and still fail because the crate accelerates too aggressively.

Math and motion should agree If the ratio doubles, torque should roughly double while rpm should roughly halve. The canvas and gauges are there to make that trade visible.