🧪 Gear Speed Lab: step-by-step build

Gear Speed Lab, completed model

Two cranks, two gear pairs: one makes things FAST, one makes things STRONG.

Welcome to your very own science lab! Real engineers test their ideas on a test bench before building the real machine. On the left side a giant gear turns a tiny gear — so the propeller spins like crazy. On the right side it is the other way round: a tiny gear turns a giant one, so the pointer moves slowly but very strongly. Which side is better? That depends on the job! The propeller and the pointer ride high on tall axles, so they can sweep right over the other crank without touching it.

  • Level 2 of 5 (easy)
  • About 20 minutes
  • 13 steps, 39 parts
  • Powered by: Hand-crank
  • Series: Starter Builds

What you will learn

Build these first

  • ⚙️ Gear Friends: Three gears holding hands — spin one and they all dance. (level 1 of 5, about 8 minutes, 6 steps)

Parts you need

  • 1 × Open frame 5×11
  • 3 × Beam 5
  • 4 × Black pin (grippy)
  • 1 × Axle 4
  • 10 × Half bush
  • 2 × Giant gear (40 teeth)
  • 2 × Hand crank
  • 1 × Axle 7
  • 2 × Tiny gear (8 teeth)
  • 6 × Bush
  • 1 × Beam 7
  • 2 × Red axle-pin
  • 2 × Double cross block
  • 1 × Axle 5
  • 1 × Axle 8

Steps

  1. Lay the 5×11 frame flat: this is your lab bench. Hold a 5-hole beam flat under the short end and push two black pins down through the corner holes into the beam. This is the front foot.
  2. Back foot: another 5-hole beam under the frame, pinned through the two side holes one in from the far end (the 10th hole on each side).
  3. Left crank: push a 4-axle down through the 2nd hole on the left side. Slide a half bush onto it under the frame and another on top of the frame, so the axle cannot slide up or down but still turns.
  4. Drop the giant 40-tooth gear onto it, push the red hand crank on above the gear (handle up) and lock it with a half bush on top.
  5. Propeller axle: a long 7-axle in the 5th hole, with a half bush under the frame and one on top, just like the crank.
  6. Slide the tiny 8-tooth gear on so it meshes with the giant gear (turn the crank a little until the teeth slot together), then stack two full bushes on top of it.
  7. Propeller: press the red 7-hole beam down over the axle onto the bushes. Push a red axle-pin, pin end down, into the beam two holes from the middle, then press a double cross block down over the axle and the axle-pin.
  8. On the right it is the other way round. Right crank: a 5-axle in the 8th hole on the far side, with a half bush under the frame and one on top.
  9. Slide the TINY 8-tooth gear onto it and hold it down with a half bush spacer.
  10. Pointer axle: the long 8-axle in the last (11th) hole, a half bush under the frame and one on top, then the giant 40-tooth gear meshing with the tiny one. Fit it now, before the right crank lever is in the way.
  11. Back on the right crank axle: push the second hand crank on above the spacer (handle up) and lock it with a full bush on top.
  12. Stack three full bushes on the pointer axle, on top of the giant gear. They lift the pointer high above the right crank.
  13. Lock the pointer: a double cross block over the axle, a red axle-pin (axle end down) in its end hole, then press the yellow 5-hole pointer beam down over the axle and the axle-pin.

Play time

Hold the bench by its frame and race the two cranks! Then gently touch the propeller and the pointer with a finger. Which one is easier to stop? Do not pull or bend the tall propeller and pointer axles.

Build next

  • 🔬 Compound Counting Bench: Two five-to-one stages multiply: count 25 input turns for one output turn. (level 2 of 5, about 20 minutes, 7 steps)
  • 🏎️ Steering Go-Kart: Turn the steering wheel and the front wheels really turn — just like a real car. (level 3 of 5, about 30 minutes, 25 steps)
  • Worm-Gear Crane🏗️ Worm-Gear Crane: Crank the worm gear to lift the boom — then let go. It stays up by itself! (level 3 of 5, about 30 minutes, 15 steps)
  • 🌬️ Bevel-Gear Windmill: Turn the handwheel at the bottom — the sails spin at the top! (level 3 of 5, about 25 minutes, 16 steps)
  • 🔋 Motor Buggy: Your first car that drives by itself — with a forwards/backwards switch and headlights! (level 3 of 5, about 30 minutes, 20 steps)
  • 📡 Spinning Radar: A motor-driven radar dish that sweeps round and round on a turntable — with a blinking light. (level 3 of 5, about 25 minutes, 15 steps)
  • 🎡 Crank Cruiser: Turn the handle and the car rolls — every turn of your hand spins the wheels three times! (level 2 of 5, about 18 minutes, 9 steps)
  • Sliding-Gear 2-Speed Cart🕹️ Sliding-Gear 2-Speed Cart: Your first real gearbox: slide the crank axle to switch between strong gear and fast gear! (level 2 of 5, about 22 minutes, 8 steps)
  • 💨 Gear-Up Speeder: The spring engine sits up high and turns a BIG gear, which spins the wheels faster! (level 2 of 5, about 25 minutes, 11 steps)
  • 🐢 Pull-back Tortoise: Slow but super-strong: a spring car that can climb up a book! (level 2 of 5, about 30 minutes, 12 steps)
  • ⚙️ Clutch-Gear 2-Speed Car: Push the gear lever and a driving ring grabs a different gear: 1st climbs, 2nd races! (level 3 of 5, about 45 minutes, 18 steps)
  • 🌪️ Ripcord Top Launcher: Pull a toothed rack and watch two gear stages turn the top. (level 2 of 5, about 20 minutes, 18 steps)
  • 🌀 Flywheel Friction Car: Vroom it on the floor, let go — and it keeps on rolling! (level 2 of 5, about 25 minutes, 5 steps)
  • ⏯️ Geneva Step Counter: Turn the handle smoothly — the pointer moves in jumps: click… wait… click! (level 3 of 5, about 30 minutes, 9 steps)