Minifig Scale
Lego crane

This is a minfig scale (about1:40) model of a mobile crane. It features a ten wheel chassis (8 wheel steering) and a telescoping boom.

The following pictures show it gets set up.

First, The out riggers are extended out, providing a stable, oversized base.

next the special rtuck and trailer carrying the jib boom is positioned in front of the crane. The trailer then raises the jib into position.

At this point the hook is disconnected from the main boom and the jib is secured in place.

Now the jib winch is connected and the boom lifts the jib off its trailer.

The booms are then lowered down a bit sothe hook can be attached to the end of the jib.

Finaly, the main boom is raised fully and extended. The crane is now ready to work.

Construction notes:

• The steering system is designed so the wheels closer to the center axle will steer very little, the rear wheels steer 1.5 times more (through a 12:8 gear ratio) and the front wheels steer twice as much (through a 16:8 gear ratio). The proper direction is achieved through a combination of gearing and positioning the steering racks either ahead or behind each axle.
• The Technic turn table was originaly powered by a micro motor, but it was not really powerful enough and it was needed for another project, so it was removed.
• The pneumatic piston used to raise the main boom is actualy a pump from the old pneumatic system (single acting) with its spring removed. This cylinder has the longest stroke available from Lego.
• The main winch uses the newest (as of June 2004) motor from Lego: altough quitenoisy,it provides a good amount of speed and torque for this crane. Located in the back of the super structure, it also makes a nice counter weight.

Being a minifig scale model, I wanted to make sure that despite its large dimensions (over 39 studs long and about 9 studs wide), it could negociate Lego roads without problems. This animation shows that it works!

This page is Copyright 2004, David Wegmuller. For website feedback, send a message to webmaster at wegmuller dot org. For content feedback, send a message to david at wegmuller dot org. Lego and Lego Technic are trademarks of the Lego Group. This website is not related, sponsored or endorced by the Lego Group.