Report on the assembly of the R 934

Click on the pictures to see a larger version.

Shortly after the visit of the Modellshow Europe 2002, I wanted not only to build kits or buy ready-made models but to build models rather “from th scratch”.
After a lot of preparations, like collecting information on real machines, I finally started with this project: A Liebherr R 934 equipped with a Krupp concrete crusher.

Cab guard

Cab guard shortly before completion

I decided to build the guard for the operator’s cab at first. This consists of a frame, which parts I cut and milled from 0.5 mm (~1/64″) brass sheet metal. Into this frame, I soldered cross bars made of 0.8  (1/32″) brass wire. The guard bars itself were made from 0.5 mm (~1/64″) wires.
On this picture, you can see the already finished top guard to the left. To the right is the front guard, where the bars are already fixed at the top end. Meanwhile, the lower ends of the bars have been cut length, bend down and soldered to the frame too.

Concrete crusher

The next step would be the concrete crusher which proofed to be a lot more difficult to build. But luckily, I had the opportunity to find a Krupp CP 2300 G on a demolition site, of which I was able to take pictures and dimensions. This made drawing plans a lot easier.
The crusher itself is mostly built from 0.5 mm (~1/64″) brass sheet metal. Only the front and the top part of the “mouth” are made from small, solid brass blocks.
Fig. 2 shows this upper part. You can see that the front tooth (as well as the other teeth) is made from a 1×2 mm (3/64″×5/64″) rectangular brass rod and already in place. On the next picture, you can see an intermediate stage: The main part of the body and the top part of the mouth are finished, the rotating assembly and the connection to the base model are still missing. The preliminary assembly should give you a better idea of the model.

Upper part of the mouthParts of the crusher, preliminary assembled.
All parts of the crusher prior to painting

After a long time of not doing any work on the model, I finally started to finish the crusher. Meanwhile, a fellow model builder had kindly made a rotating assembly for me on his lathe. With this, I was able to give the model full rotating operability like the real machine. I just glued the lower part to the main body of the crusher. On the top part, I built the rotating drive. In order to save weight, I used a rather crude, solid plastic block as a basic form. This was in turn decorated with small brass wedges in order to resemble the reinforcement structures of the real machine. A brass plate went to the front, that would later bear the hyraulic connectors. On top of all this came another brass plate as cover, on which in turn I glued a quick hitch from CMM Schwerlast.
In order to be able to disasemble the crusher later on but have a fully functional model nonetheless, I figured out a rather complex mounting of the hydraulic cylinder: The cylinder is mounted with a well known brass rivet to a small piece of brass U-profile. The profile features a M2 thread on its top. At assembly, a M2 screw is inserted through the upper part of the rotary assembly screwed into the U-profile and secured against unwanted loosening with a drop of glue there. With this, the cylinder ist mounted in a stable yet disassembable way and the rotary assembly is functional too.
As a last finish, some more details, like imitations of inspection hatches and a lift ring were affixed. The reinforcement of the “mouth” and cylinder bearings were made from brass washers.
After completing the construction, the model’s surfaced was smoothed with filler and sandpaper and painted. Finally, some decals were applied and the final assembly took place.

Finished crusher

Boom and stick

As a first step, I made some blueprints of the side frames of the boom and the stick on my computer with the help of Liebherr side view, the Liebherr datasheet and some photos. Since I wished to have base model especially fitted for demolition work, I decided to build a straight 6.50  (21 ft) boom and a 3.10 m (10 ft) stick. With this, a real machine would be able to reach a large height and would have at the same time enough lifting capacity for coping with the 3.2 metric tons (7055 lb) of the crusher.
After the blueprints were finished, I had the parts made at a CNC milling service from 0.5 mm (~1/64″) brass sheet metal.

To be continued …