WPM


Graupner PistenBully

Graupner PistenBully Chassis Re-Inforcement
Graupner PistenBully Gear Box Repair


Graupner PistenBully Chassis Re-Inforcement

The plastic tub of the Graupner PistenBully is starting to show it's age. Due to embrittlement of the material fractures may occur. Especially the flange of the powered shaft is under high load. Therefore we added an aluminum L-profile (10x10x2 mm) to distribute the load on the two forward positioned axle flanges at our Graupner. The aluminum profile was filed to fit the axle flanges. This drawing (PDF) may serve as a starting point.

The strengthening fins of the flanges have to be filed flat in those areas where the aluminum profile will rest. For better adhesion roughen the surface of the aluminum and plastic with 150 grain sanding paper in those areas where glue will be applied. Thoroughly decrease and glue in place with 2-component epoxy.

Fahrwerksverstärkung

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Graupner PistenBully Gear Box Repair

One of the gears of the 3rd gear set was destroyed at our Graupner PistenBully, after the shaft blocked. To avoid this regular greasing of the bearings should be done. The Graupner gears are module 0.75, which is not part of the prefered DIN standard and as such hard to get. A fitting gear set for the given shaft distance is possible with module 0.7 and 14/35 teeth. The small change in gear ratio is towards slower speed, which adds some torque. The mis-match of the shaft distance is only 0.1 mm. Such gears are available at Mäder.

The holes of the gears have to be adjusted on a lathe. The plastic gear has an inner bore of 7.5 mm and is pressed on a reeded shaft, which can easily be done on a vise. The brass gear has a 4 mm hole and got a M3-thread for the worm bolt.
The damaged plastic gear was reduced step by step on the lathe until only a small sleeve was left, which was cut with a knive and removed.

beschädigtes Getriebe
Picture above: damaged gears

Getriebe repariert
Picture above: repaired gear box with new gear set

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