Unit 3: Motors, Gearboxes, and Mechanisms

This is a self-paced Unit. Work through the three lessons in order, keep the evidence you create, and finish with the Unit Wrap-Up. You do not need access to a competition robot for every task. When hardware is unavailable, use the simulation, diagram, log, photo, or documented-analysis path described in the lesson.

The question

How do teams trade speed, torque, weight, complexity, and reliability when choosing mechanisms?

What you will understand

By the end of this Unit, you should be able to explain the central system relationships behind motors, gearboxes, and mechanisms instead of relying on part names or memorized steps. You will trace cause and effect, identify important dependencies, and recognize at least one failure mode that can produce misleading symptoms.

What you will do

1. Read Motors Turn Electrical Power into Motion and build the foundation.
2. Continue with Gearing Changes the Tradeoff and inspect the mechanism, boundary, or tradeoff.
3. Finish Choose a Mechanism You Can Defend by applying the reasoning to a real, simulated, or documented FRC system.
4. Keep the artifact and evidence you produce. You will reuse earlier work in the final competition-readiness dossier.

What you will produce

Your main Unit artifact is a mechanism tradeoff sheet with a gearing calculation and test plan. It should be understandable to another learner without a verbal explanation. Label assumptions, measurements, device names, paths, states, or decisions where they matter.

How this Unit builds

The course is cumulative. Each Unit adds another layer to the same robot:

game objective
    ↓
system architecture
    ↓
mechanism + electrical system
    ↓
robot software
    ↓
sensing + control
    ↓
autonomous + driver operation
    ↓
strategy + reliability
    ↓
competition readiness

Unit 3 contributes evidence to that chain. Do not throw away a useful diagram or test record just because the Unit is complete.

Key vocabulary

torque, speed, gear ratio, reduction, load, stall, mechanical advantage, prototype

Estimated time

Plan for roughly 2–4 hours. Hardware testing, CAD, fabrication, or deeper extensions may take longer. The goal is evidence, not racing the clock.

Evidence to keep

Keep the Unit artifact, at least one concrete observation or test result, one identified limitation or failure mode, and any revision you made after checking the evidence.