January 23, 2012

Mini Mobile Crane

After finishing my MOD of the LEGO® Technic 9397, I wanted to add pneumatics to other sets. My choice was the Mini Mobile Crane 8067.  I especially like the cabin so I wanted to reuse it completely. The mechanism of the outriggers is also well-done so, I reused them too.

To  make it more interesting I decided to use its parts and make an MOC loosely based on the Liebherr LTM 1200 5.1.

And this is what I came out with. 

All functions are comparable to bigger scale models like e.g., the 8460.

- 5 axle steering system actuated by a 20t, 12t gear reduction on the back
- Four outriggers stabilize the crane while lifting
- A rotating crane, mounted on the new turntable elements (99010, 99009)
- The crane is lifted pneumatically with a Pneumatic Cylinder (47224c01)
- The crane consists of two booms so it can extend
- A hook with rope
- Dummy engine

The most difficult part was the steering system and it took several attempts to realize it. I got inspired by the LEGO® Technic 9390 and developed the idea. This result in a modular system of small size. The turning radius is nearly 40 cm.   

Note: None of the axles are meeting in a pivot point which causes some problems (slipping wheels, vibrations), especially on the front axle. I made this compromise according to the small scale.
More detailed pictures of the steering mechanism to be found on Brickshelf.

The Boom is lifted by a Pneumatic Cylinder (47224c01). Two Small Pumps (x191c01) provide the air and I used a Technic, Shock Absorber 6.5L, Complete Assembly (Normal Spring) (731c05) to run the pumps manually. With an 1L stroke you have to push about 20 times to lift the heavy boom.

The boom is extendable and uses Erik Leppen's design. It's really strong and fits the scale quite well.

I'm very happy how everything turned out and I hope you like it as well.

More detailed pictures to be found on Brickshelf.
Check if you have all the needed parts to build it yourself using Rebrickable.com
You can also download the LDD File directly.
LEGO® Digital Designer lacks in some parts, you have to replace the fake parts of these:
- Pneumatic Cylinder (47224c01)
- Two Small Pumps (x191c01)
- Pneumatic Switch (4694b)

With best regards,

January 18, 2012

Motorized Pneumatic Pump

One of my plans for 2012 is to build a pneumatic walker. Therefore, I have to guarantee a sufficient airflow. Main restrictions are space and of course weight. So, my first decision was to use only the Power Functions M-Motor (58120c01) instead of the far more powerful, but two times heavier XL-Motor (58121c01).

After several attempts with different arrangements and a destroyed Pneumatic Pump (5107-1) (yes, I removed the spring and afterwards it couldn't hold the pressure anymore), I started to copy some designs from other builders like e.g., Sariel's compressor and rocking compressor. But I was pleased with none of them.

I wanted something more stable and reliable and when I discovered radbot's concept, I was enthusiastic to build a frame housing those 8 Small Pumps (x191c01). To build it, I used 5 "Liftarm 5 x 7 Open Center Thick" (64179). Because of their numerous Technic holes, you can easily implement the pump in any other creation. The small dimensions of 7x10x10 studs improve the implementation as well.

Because of the 5.5L of the Small Pumps, I used the Pin Connector Perpendicular Long (32557) in order to achieve a 2L displacement on the crankshaft.

Pin Connector Perpendicular Long (32557) in order to achieve a 2L displacement on the crankshaft
 The two crankshafts are counter-rotating

To show you the pump in action, I made some videos. Especially the fancy crankshaft movement made me happy.

More detailed pictures to be found on Brickshelf.

With best regards,