This Instructable is for building a simple two-legged Lego walker,basically just the bare bones version on which you can add anything you want.My idea was to turn it into a Swan,maybe the finished idea will be made into a separate Instructable.

This is my two-legged version of the dog from the Lego Technic ideas book nr 8888.Personally I found the speed a bit on the slow side,so I changed the 8 tooth gearwheels on the outside to 24 tooth ones.The geartrain itself stayed the same.

Please note:The two screenshots from the Lego Digital Designer are a little different than the finished walker:

The finished walker uses an old style motor and the connectors are also different since I couldn't find those on LDD.

Step 1: Parts You Need and First Step

Since this is a simple walker it only has less than 70 pieces.Many of the parts are not critical and can be changed if you don't happen to have them.

Step one is to take two 1 x 16 technic bricks,two 40 tooth gears and two pegs with cross axles.

Put the pegs in the middle of the gears and place them in hole nr 7 (from the left).

Next take three 24 tooth gears and a 8 axle.Place the axle in hole 11 and place 1 gear on the inside against the side of the brick,and attach the other gears so that they mesh with the 40 tooth gears.

Take two 24 tooth gears,one peg with cross axle,a bushing,and a 6 axle.Put the peg in the middle of one of the gears and place it on the inside on the left side of the other gear so that they mesh.

Slide the axle in hole nr 5 with 1 of the gears and the bushing.The gear needs to mesh with the other two,and the bushing needs to slide against the brick on the other side.

This concludes the lower geartrai.Check if it rotates freely.

Step 2: Upper Geartrain

Take two 1 x 8 Technic bricks,three 6 axles,two 24 tooth gears,three 8 tooth gears,a crown gear and three bushings.Slide the axles in hole 2,4 and 6 in one of the bricks.On the axle in hole 2 put a 8 tooth gear on one side and a 24 tooth gear on the other side.On the axle in hole 4 put a bushing a 24 tooth gear and 8 tooth gear.On the axle in hole 6 put a bushing,a crown gear(with the teeth facing away from the bushing,a 8 tooth gear and a bushing.Put the other 1 x 8 brick opposite the first one.use the photo's to help you.

Step 3: Complete the Geartrain

Take the 1 x 8 plates and put them on the 1 x 16 Technic bricks(the lower gear train).You need to stack two of them together.

Take the upper gear train and put it on top the lower gear train starting at stud nr 7.Test to see if all the gears move freely.

Take one of the 2 x 6 plates and attach it to the underside of the front.Take the 2 x 6 plate and attach it to the underside at the rear with one stud sticking out.Take the 2 x 4 brick and attach it to the plate at the rear,take four 1 x 2 bricks and attach those,stacked,under the 2 x 4 brick.

Take two 1 x 2 bricks and one 1 x 2 technic brick and attach those on the underside in the middle of the 40 tooth gear.Do this on both sides.Connect the two rows with a 2 x 6 plate.

Step 4: Give It Some Legs and a Motor

Take two pegs,two pegs with a cross axle,two catches,two 6 axles and two bushings.Put the pegs in the first hole from the center of the 40 tooth gears.This can be to the right- or the left side,but do this on the same side for both the gears when they face you.Remember this walker walks the same like you do:one feet forward,then the other.

Attach the catches to the pegs,and the axles to the pegs.Slide the other catches on the axles,and attach the cross end of the pegs with cross axle on the catches.The other end goes into the 1 x 2 technic brick.

Put a bushing with the cross end downwards on the end of the axle.

Put the 4 x 4 plates on the end of the axles,with the bushing in the middle.

Take the motor,put a 8 tooth gear on the axle,and place the motor at the rear end so that the 8 tooth gear meshes with the crown gear.

The motor runs on 4,5 Volt...so you need 3 x AA or AAA batteries and a batteryholder(or box) and some wires and plugs to connect them all.

Step 5: Make It Into a Four Legged Walker

It is very easy to turn this walker into a four legged one.Here's what you need :

-two 24 tooth gears

-two 40 tooth gears

-1 axle 6

-1 axle 8

-4 connectors

-2 bushings

-2 pegs

-4 pegs with cross axle

-2 4 x 4 plates

-2 1 x 2 technic bricks

-1 2 x 6 plate

Remove the 2 x 6 plate on the left underside ,you will place this later under the leg columns..Move the two 40 tooth gears all the way to the left,in the first hole.Change the first axle 6 to a axle 8,you will need the axle 6 for one of the extra legs.Put the 24 tooth gears on the outside,so that they mesh with the 40 tooth gears.The columns of 1 x 2 bricks can also be moved all the way to the left.Put the 2 x 6 plate under the columns.

Remove the column of 1 x 2 bricks from the rear,you need 2 of the bricks on each side for the leg.

Take the two 40 tooth gears,place a peg with cross axle in the middle and put them in the last hole on both sides.

Attach a connector to the peg and a 6 axle to the connector.Slide a connector on the axle and place a peg with cross axle in the connector.Take the 1 x 2 bricks and the 1 x 2 technic bricks and make two columns.Place these all the way at the end.Put a 2 x 6 plate under the columns.Put the pegs into the technic bricks. Slide a bushing on the end of the axles.Attach the 4 x 4 plates to the legs.

And that's all you need to do.

Step 6: Improvements

There are a number of things you can do to improve both the the two- and four-legged walkers:

-replace the 4 x 4 plates that make up the feet by wheels for a better grip(see first photo)

-give the walker longer legs: use a 8 axle instead of a 6 axle.

-move the peg on the 40 tooth gear one hole further from the center,so the walker takes bigger steps(see last video)

-In the third photo the gears on the outside are replaced by pre-Technic gears:the yellow one is bigger than the 40 tooth gear,so you can make your walker take bigger steps.