Step 1

Start with base plate: red Plate 5x6 with hole
Step 2

Place two red Plate 1x6 pieces on the base plate
Between them, place one red Plate 1x1, one white Tile 1x4, and one clear Plate 1x1
Step 3

Place two clear Plate 1x6 pieces, one on each red Plate 1x6.
One red Brick 1x2 is placed on the far clear Plate 1x6
Step 4

The Technic 1x4 Gear Rack is attached to two blue Technic 1x1 Bricks with Hole
This assembly rests on the white tile, and is free to slide back and forth between
the clear plates
A red Tile 1x1 is placed above the red Plate 1x1.
Step 5

Four Technic Brick 1x1 with holes are placed on the plate -- two blue in the corners,
two yellow one peg in from the corners. These bricks are in pairs across from each other.
One Technic Brick 1x2 with one hole is placed on the red Brick 1x2
Step 6

Techinc Axles are inserted: 6 Axle through hole in Brick 1x2, 8 Axle through holes in
Bricks under gear rack, each of two 10 Axles through a yellow Brick 1x1 and a blue Brick 1x1
The 6 Axle is the input, the 8 Axle is the transmission, the far 10 Axle is the power and the
near 10 Axle is the output.
Step 7: Input Off -> Transmission Engaged -> Output On

Each 10 Axle is capped with Technic Bush 1/2 next to the yellow Brick 1x1 with hole and
a Technic Gear 8 Tooth next to the blue Brick 1x1 with hole.
The 8 axle is capped with a Technic Bush 1/2 next to the blue Brick 1x1 with hole and
a Technic Gear 24 Tooth on the end. The 6 Axle is capped with a Technic Bush 1/2 and
a Technic Gear 8 Tooth
The Technic Gear 24 is the transmission gear.
Not pictured: A rubber band is stretched between the two yellow bricks, and through the legs
under the Gear Rack. This keeps the transmission gear engaged when the input is off.
The transmission gear transfers power from the input to the output, causing the output to be on.
Input On -> Transmission Disngaged -> Output Off

When the input is on, it spins the gear on the gear rack, which fights the rubber band
and disengages the transmission. No power is transferred from the power axle to the output
axle, causing it to be off.
Created by LeoCAD