🎠 Idler Parade Car: step-by-step build

A parade of gears rides on top — each one spins the opposite way to its neighbour!

This car carries a whole parade of gears on its roof, and each gear has a red dot so you can follow it. Push the car: the back axle turns the first gear, the first gear turns the second, and so on down the line. Look closely — every gear spins the OPPOSITE way to its neighbour, but they all go exactly as fast. Gears in the middle of a row are called idlers: they pass the turning along and flip its direction.

• Level 1 of 5 (super easy)
• About 20 minutes
• 13 steps, 37 parts
• Powered by: Push
• Series: Gearbox & Drivetrain Cars

What you will learn

• Idler Gears & Direction: A gear in the middle flips the direction back.
• Gears: Gears are wheels with teeth that push each other round.
• Beams & Holes: Beams are the bones of every Technic model.

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

• 3 × Beam 13
• 2 × Axle 8
• 5 × Half bush
• 2 × Bush
• 5 × Medium gear (24 teeth)
• 6 × Black pin (grippy)
• 2 × L-beam 2×4
• 4 × Tan axle-pin
• 4 × Red axle-pin
• 4 × Yellow-hub wheel

Steps

1. Stand a 13-hole beam on its edge — the left side of the car — and push an 8-long axle through its first hole and another through its last hole.
2. Lock the beam on the axles: a yellow half bush on the outside end of each axle, a grey bush on the inside of the front axle, and a 24-tooth gear on the inside of the back axle.
3. Slide a grey bush onto the back axle right behind the gear and a yellow half bush onto the front axle, then slide the second 13-hole beam onto both axles until it touches the half bush.
4. Push four black pins into the inside of the right-hand beam, in holes 5, 6, 8 and 9.
5. Snap two small L-beams onto the pins, long legs pointing up, feet pointing at each other.
6. Push a black pin into the top hole of each post.
7. Press the long 13-hole gallery beam onto the two pins, so it lines up above the car.
8. Push a tan axle-pin into the last gallery hole and slide a 24-tooth gear on it — right above the driver gear. Turn the whole axle-pin and gear slightly so teeth fit into the driver gear’s gaps.
9. Add two more gears on tan axle-pins, every third hole, so each one meshes with the one before. Fit each gear’s teeth into its neighbour’s gaps.
10. Add the last gear of the parade, fitting its teeth into the previous gear’s gaps.
11. Push a red axle-pin into the upper outer hole of each gallery gear, following its pictured starting angle — these are the parade flags.
12. Add half bushes to the other two axle ends.
13. Push on the four wheels.

Play time

Note each red dot’s starting position, then push the car one wheel-turn. Does each dot return to its own starting position? Which gears spin clockwise and which anticlockwise?

Real-world inspiration

Sariel's Technic gears tutorial (idler gears) — https://sariel.pl/2009/09/gears-tutorial/