Intakes#
An intake acquires a game piece from the field and is one of the most common mechanisms because nearly every game has something to pick up. Typical designs use rollers (compliant wheels, polyurethane rollers, or surgical-tubing/star rollers) spun by a motor to grab and pull the piece in. Variants:
- Roller intake — one or two rollers compress and draw the piece in.
- Over-the-bumper intake — reaches outside the frame and pulls pieces over the bumper.
- Claw/gripper — for rigid pieces that need a firm grasp.
Shooters / launchers#
A shooter scores game pieces from a distance. Most use one or two flywheels: spinning wheels that fling the piece on contact. Key design factors are wheel speed (rpm), wheel mass/inertia (to maintain speed during the shot), compression on the piece, and hood angle for trajectory. Two-wheel shooters can add backspin for stability. AndyMark and others sell COTS launcher assemblies.
Elevators#
An elevator raises a carriage vertically along rails, usually on bearings/rollers in extrusion. Two rigging styles:
- Cascade — stages extend together so the top moves faster than any single stage, maximizing speed for a given motor.
- Continuous (rigid/telescoping) — stages extend in sequence; often simpler to rig.
Elevators are driven by belt, chain, or rope/cable and require precise control, so prototype motor, ratio, and speed carefully.
Arms#
An arm rotates a payload around a pivot. Single-jointed arms are simplest; double-jointed arms reach more positions but are far harder to control. Arms need enough torque to hold against gravity (often a high reduction, sometimes with a gas spring or constant-force spring to counterbalance) and an absolute encoder to know their angle at power-up.
Climbers#
Many games end with a climb in the endgame — robots have climbed ropes, bars, chains, and platforms. Common approaches: a winch pulling the robot up on a rope/strap, a telescoping/elevator-style lift hooking a bar, or a hook-on-arm. Climbers carry the full robot weight, so they need high reduction, a ratchet or brake to hold position without power, and robust hooks.
Picking mechanisms#
Read the game manual, list every scoring action, and design the simplest mechanism that does each reliably. A robot that does two things flawlessly beats one that does five things poorly.
the part worth keeping
Key takeaways
- Intakes (rollers), shooters (flywheels), elevators (cascade vs. continuous), arms (pivot + counterbalance), and climbers (winch/lift) recur across games
- Match the mechanism to the game's scoring actions and favor reliability over feature count
- Arms and climbers need high reduction, position feedback, and a way to hold load without power
Mechanical, Build & PneumaticsMechanisms, Fabrication, and Assemblylesson 1 of 3
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where this came from
Sources and corrections
This lesson is AI-assisted: drafted from primary sources, then reviewed and edited by hand. Errors still get through. When one is reported we fix it and write down what changed, in public, in the corrections log.
sources and further reading
- projectb.net.auProject Bucephalus – Unofficial FRC Mechanism Encyclopedia
- frcdesign.orgFRCDesign.org – Mechanism Examples
clipped to this lesson
Articles that go further on this
The lesson gets you through the topic. These go wider on it, and they read in one sitting.
- 16 min readFRC Elevator and Arm Design: Staging, Rigging, Motors, Gravity, and SafetyA primary-source FRC guide to designing elevators and arms: cascade vs continuous rigging, staging, motor and gear-ratio sizing, gravity math, and safe holding./blogread it
- 15 min readHow to Design an FRC Intake: Rollers, Compression, and MotorsA primary-source FRC intake design guide: over-the-bumper vs under-bumper, roller vs wheel, compliance and durometer, compression and wrap, and motor selection./blogread it
- 17 min readFRC Flywheel Shooter Design: Compression, Speed, Backspin, and HoodingHow to design an FRC flywheel shooter: exit velocity, compression, flywheel inertia and RPM recovery, single vs dual wheels, backspin, hooding, motors, and tuning./blogread it
answer sheet
Lesson quiz
All 3 right completes the lesson. Miss one and only that question comes back, anything you already answered correctly stays banked.
0 of 3 answered
01On a typical FRC robot, what is the primary job of an 'intake' mechanism?
02Which factors are the key design considerations for a flywheel-style shooter?
03A 'cascade' elevator differs from a 'continuous' elevator because a cascade elevator is rigged so that:
Answer every question to submit.
All 47 lessons in Mechanical, Build & Pneumaticsopenclose
01 / prerequisites
02 / drivetrains
03 / power-transmission
04 / structure-materials-fasteners
05 / mechanisms-fabrication-assembly
06 / pneumatics-fundamentals
07 / pneumatic-components
08 / build-wire-program
09 / safety-rules-testing
10 / worked-examples-mini-projects
- Not read yet:Mini-Project 1: A Single-Jointed Arm From Math to Motion
- Not read yet:Mini-Project 2: A Two-Stage Cascade Elevator
- Not read yet:Mini-Project 3: A Velocity-Controlled Flywheel Shooter
- Not read yet:Mini-Project 4: A Pivoting Roller Intake
- Not read yet:Mini-Project 5: Integrating a COTS Swerve Module
11 / common-mistakes-troubleshooting
- Not read yet:Pneumatics Won't Fire: A Full Diagnostic Tree
- Not read yet:The Robot Won't Drive Straight (and Other Drivetrain Sins)
- Not read yet:Gearboxes That Grenade and Fasteners That Vibrate Loose
- Not read yet:Closed-Loop Mechanisms That Oscillate, Sag, or Stall
- Not read yet:Field-Ready Reliability: Inspection, Spares, and the Pit Checklist
12 / advanced-techniques-case-studies
- Not read yet:Characterizing Any Mechanism with SysId
- Not read yet:Simulation-Driven Design with WPILib Physics Models
- Not read yet:Motion Profiling and Superstructure Coordination
- Not read yet:Designing for Weight, Stiffness, and Manufacturability
- Not read yet:Case Studies: Learning From Open Alliance Robots