WPM


Albert's PistenBully 36.145 D

The german magazine Rad & Kette 1/2016 features an article by me about making my PB145D model and the modification. It's in German language.

The article can be downloaded here as PDF, with friendly permission by the magazine

PB120 einst
The original PB145D

The model in scale 1:8 of the Kässbohrer PistenBully has been built by Albert in his teenage years 1974/75. We are pretty sure that this is the first RC model of a snow cat worldwide. The first run was on March 29, 1975.

Due to the limited possibilities at this time the powertrain and the tracks were not very sturdy. The model did run, but it was quite clear after the first tests that improvements were necessary. These somehow got stuck, and it took 35 years before a new chassis and new tracks were built.

 

PB120 mit ersten Ketten
PB145D on March 29, 1975 with the first set of tracks with wood/plastic bars
Albert mit PB120

These rare pictures show the PB145D on March 29, 1975 with the first set of tracks, which had wooden square bars with ABS-stripes glued on top of them. These were glued with Pattex on the rubber bands. They for sure looked good, but fell off piece by piece after the first test runs. I then made new tracks consisting of bent aluminum profiles which were riveted on nylon bands.

I found these pictures by chance in May 2014 in the slide collection of my dad.

I was 14 years old on this picture.

 

Fahrgestell
The new chassis based on Pistenking technology

The driver cabin was built out of plywood and balsa wood, as well as the original chassis tub. Several different variants were tested for the gear box, at the end it was a worm drive from Fischer Technik. In the mid-seventies there was almost nothing available on the market for RC vehicles. The batteries were lead batteries with liquid acid, not sealed, so careful handling was a given.

The radio control sets were costing a fortune back then. The servos were mounted on quick exchange mounts to easily move them from one model to the other. That's why every part on this model was made from scratch, using simple methods and often without knowing the acting forces and loads.

Meanwhile a new platform has been built using aluminum profiles and sheets and glued to the tub. The original driver cabin has been repaired, and new window glasses were installed.

 

Plattform
Verkleben der Plattform mit Wanne
Glueing the platform to the tub
Kette
New "Ibex"-tracks

The PB145D was thus for the first time ready for action since more than 35 years. It took a couple more years before a new mechanism for lifting the trailing roller was made.

At Videos you'll find a video of the first test runs in 1975, as well as one form the current model.

 

 

Trailing Roller

The mechanism for the trailing roller was made with a mix of techniques: soldering and glueing hollow brass profiles and aluminum profiles and parts. The newly purchased Stepcraft CNC milling machine came to a good use.

The trailing roller is still the original part from 1975, it is from wood and was wood turned by my dad in our carpenter workshop.

The picture shows the parts before painting. The different materials are clearly visible.

For lifting a mechanically driven CTI-cylinder was chosen. It is from the first series and unfortunately not working really satisfactory. It often gets stuck in the end positions and it's power is barely sufficient for the relatively heavy roller.

The compensation of ground rubs (floating position) is performed by the pressing cylinder, which has springs inside. These springs also serve as dampers when the roller is lifted and swings to the resting position.

 

 

First test drives in snow were successful. The trailing roller creates the typical slope surface of the 70s. Most of the snow groomers back then did not have front blades, and were often just used to compress freshly fallen snow.

The hydraulic hoses were mounted after painting. The CTI cylinder gets it's power by a "electrical hydraulic hose" which was made from a suitable coaxial cable. But this was quite some fumbling.

PB145D model with the "45 Years Cult" anniversary poster of the PistenBully News #4 2014/15

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