CAT D9R tracked dozer

Caterpillar

One of the most well known manufacturers of construction machinery is Caterpillar. Once this constructor has started to build agricultural crawler tractors. In the US some of these machines are still in service. Nowadays Caterpillar has an extensive delivery program like excavators, bulldozers, dump trucks and scrapers. Next to this they also build engines for trucks and every kind of machinery.
The D9R is third largest bulldozer model. The heaviest are the D10 and the D11. The last one has an operating weight of 98.4 tonnes. This kind of machinery are often brought in action for the real heavy digging operations. They are impressive machines to see and to build.

The LEGO model

I have built this model because I wanted 'something different' on my lowloader truck than an excavator or a dragline (just look at the Scania T143EL6x4 on the 'trucks page'). In a book about construction machinery I have seen lots of pictures of bulldozers and then I have decided to build such a machine. I have calculated the loading capacity of the lowloader and searched which machine was most suitable for my truck. The D9R, with its operating weight of almost 50 tonnes, has came close to what can be carried with the lowloader. Besides, I think the CAT bulldozers are more beautiful than that of the other manufacturers. Very characteristic are the caterpillars which are not straight. Next to this it was very easy to find some information about this machine, because I have some contacts with the CAT importer in the Netherlands.
Because I had never build a bulldozer before, OK, afterwords of the one from set 856, I thought it was rather difficult to plan where to start. In the brochure there is a picture of the frame, so that was the most logical part to start with. After the frame the caterpillars have followed and, as always, when the undercarriage is finished the rest comes naturerly. During the construction I have discovered how gigantic this machine is in real life with the standard LEGO model in the back of my head. Especially when I have started with the blade I really was aware of it.
The machine has a V8 engine with working pistons. The engine block is driven by a 9 volt motor. The engine block is built from some brochures and specifications. Behind the engine, underneath the operators cabin, there is a compressor which is also driven by a 9 volt motor. The compressor provides that the ripper at the back of the machine can move. This ripper has two pneumatic functions (up and down, forward and backward). The shape of the operators cabin is also different; namely the doors are sloped. To manage this, I have used plate hinges. The interior is just like the real machine; an adjustable seat, a set of instruments and two joy sticks. Above the cabin there is a safety bar. Unfortunately it was not possible to move the dozer blade, because LEGO's pneumatic cylinders are to small. Otherwise I have made the cylinders from round 2x2 bricks. The dozer blade was also not easy to construct. I don't have many sloped yellow bricks, so I have had to invent something different. I had the idea to use plates and hinges very quickly. The model can drive, even with the dozer blade on it. However, I have never tried it in the sandbank ... At least the model is finished with several details, like an exhaust pipe, lights, hand bars, footboards etc.
I am very satisfied with the result of this model and I though it was a shame to break it off. Sometimes you have to construct something different, I need the materials.

On the last picture you can see the original machine. This picture is from one of the brochures which I have used to build this model.

Other data

Length	65 cm
Width:	22 cm
Height:	33.2 cm
Track length:	40.2 cm
Construction:	about 50 hours
Date:	March / April 1999

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