How to Make a K'Nex Transmission

Written by grahame turner
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The transmission on a car allows you to change the speed and torque going from the engine or motor to the wheels. Using some of the pieces included in a K'NEX set, you can recreate the effect, making a device which you can shift from low speed to high speed. All of the pieces to build this model are included in their Education series set, "Exploring Machines," although you will likely be able to find these pieces in your collection of parts.

Skill level:

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Things you need

  • K'NEX beams and connectors
  • K'NEX gears
  • K'NEX spacers
  • K'NEX motor

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  1. 1

    Clip a half-circle of a 3D connector into the channel in a full-circle 3D connector. Make three more of these pieces.

  2. 2

    Place the four connectors flat-side down, in a square shape about 2-inches apart. Join these pieces with blue connector rods. Point this base so that one of the blue rods faces you.

  3. 3

    Join two half-circle 3-D connectors to each other, and make two of these pieces. Attach them to blue connectors, and place them upright on the top-two corners.

  4. 4

    Attach short green beams to a flat white connector. Place one at 3 o'clock, one at 6 o'clock, and a third at 9 o'clock. Make two of these units.

  5. 5

    Clip a blue rod into the first slot on a 90-degree connector. Attach it to the 9 o'clock beam on the white connector. Make two of these roughly L-shaped units.

  6. 6

    Attach the blue rod on an L-shaped unit upright on the bottom-left corner. Clip the white wheel into the 3-D connector on the top-left corner. Repeat on the other side.

  7. 7

    Insert four white rods into the right side of the model, so they point inward at 45-degree angles and form a loose X-shape.

  8. 8

    Make the gear channels by attaching a 45-degree angle connector perpendicular to a white connector. Hold the beam perpendicular to the slot on a connector, and push the connector down until it snaps into place. Repeat with a second connector on the other side, so the two point in the same direction. Attach a 90-degree connector between the three, so that the corner points in the opposite direction.

  9. 9

    Slide three narrow spacers onto a blue beam. Clip the gear channel onto this beam, then thread on two large spacers and a final narrow spacer. Clip this unit between the two 3-D connectors.

  10. 10

    Thread a white wheel, three narrow connectors, a large gear and a beige connector onto a long green rod. Insert the pin on the beige connector into the small notch in the large gear. Thread a large spacer, three more narrow spacers, and another beige spacer onto this, then attach a small gear to the last spacer. This becomes the powered shaft.

  11. 11

    Clip four white beams into a white circle connector. One each at the 12 o'clock, 3 o'clock, 6 o'clock and 9 o'clock positions. Slide this onto the end of the gear rod.

  12. 12

    Clip the gear rod into the base, so that the white rods on the endmost connector fit into the left-hand side of the frame at about a 45-degree angle, to mimic the X on the other side. Clip the other white connector into the centre of the right-hand X.

  13. 13

    Build the gear shifter. This is a long green rod with the following threaded onto it, moving from left to right: a large gear, a beige connector (attached to large gear), an endcap connector, a beige connector and a small gear. Attach a yellow rod to the endcap piece.

  14. 14

    Insert the gear shifter between the two upper white circle connectors. Slip the gear stick, the yellow rod, between the two pieces of the gear channel.

  15. 15

    Build the drive gear by threading the following pieces onto a long rod, from left to right: four narrow spacers, a small gear, a beige connector, a second beige connector, a large gear, two large spacers and a final narrow spacer.

  16. 16

    Attach the drive gear to the 90-degree connectors on the corner of the model. The large gear on this gear shaft should be above the large gear on the lower shaft. Adjust the first spacer on the drive gear to hold the gears in place.

  17. 17

    Attach the K'NEX motor to the right-hand side of the model, attaching it to the powered motor.

  18. 18

    Make another flat-backed 3-D connector. Attach four blue rods to the flat part, again at 12 o'clock, 3 o'clock, 6 o'clock and 9 o'clock points. Attach this to the left-side of the driveshaft.

  19. 19

    Switch the motor on to start the powered shaft spinning. Lift the gear shifter out of the channel, and shift it to the left or right to start the driveshaft moving. Shift the other direction to make it spin faster or slower. Return the shifter to the channel to put the device back in neutral.

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