|Prinoth Leitwolf with Power Functions (2007)|
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|Example instructions (PDF):|
|'How does it work' video:|
After the completion of the first Prinoth Leitwolf LEGO® model based on the 'old' technic treads (#3873) it became clear that this model has some serious disadvantages. The old technic treads are to fragile, the electro motors (#71427) are not really powerful enough to drive the groomer and the undercarriage lift mechanism could be improved. With the launch of a new track system and (remote) power functions by the LEGO group this year, it was logical step to upgrade the groomer I developed before.
This upgrade started on Monday the 20th of August, when I bought the bulldozer set 8275 at the LEGO® Shop in Oberhausen - Germany. The project is called Prinoth Leitwolf NT (New Treads) and took me about 3 months to complete.
But the result is here! The model looks
more realistic, is fully remote controlled (tracks and tillers) and is powerful
in driving. The undercarriage lift mechanism is now based on 2 pneumatic
cylinders. 'Unfortunately' the undercarriage can only be raised / lowered at
the front side; the back side is fully occupied with the new power XL motors and
demands for a proper construction (otherwise the model is pushed apart by the
force of the XL motors). The V6 engine is still inside and working. The battery
box is placed behind the chairs of the cabin and can be easily removed. The
receivers are placed just under the roof of the cabin. Last but not least, the
tracks do have a tension mechanism by using shock absorbers (6.5L).
An improvement after testing the model in real snow was the mounting of snow bars on the tracks, which gives the groomer much more grip and makes the two parallel tracks 'act as one track'. However, for just 'home play-ability' this is not necessary.
Notice that the model can be build in 2 designs:
* with loading platform only
* with drum winch equipment (just 'click on and lock')
The technic specifications of the 'Prinoth
Leitwolf NT' model
* Independent track movement, powered by 2 power functions XL motors
* Remote controlled via infrared (power functions)
* Front blade & rear tiller powered by 2 power functions medium motors
* Working V6 engine
* Undercarriage height adjustment (front side) based on pneumatic
* Track tension mechanism based on shock absorbers
* Front blade rotation to the left & right
* Rotating cutter rollers in the rear tiller
* Drum winch with rope & hook
Other non-technic functions are:
* Cabin doors open & close
* Easy access to battery box
* Engine roof open & close
* Front blade wings open & close
* Rear tiller front & side wings raised & down
* Drum winch boom rotates 360 degrees
* Drum winch equipment overturn to the rear side (access to engine room)
The dimensions of the Prinoth Leitwolf
NT (with drum winch) are:
* Length: 55 cm
* Width: 23 cm
* Height with lowered undercarriage: 21 cm
* Height with raised undercarriage: 22 cm
* Height adjustment: 2 cm (measured at the front side of cabin)
* Weight: 2,5 kg (including batteries)
* Number of parts:
* with loading platform: 2.656
* with drum winch: 2.926
* crawler tracks: 192 treads, 16 yellow sprockets, 8 black sprockets
* snow bars on tracks: 384 (288 Technic pin 1/2, 96 Technic liftarm 1 x 7)
* Development time for the upgrade: ~125 hours
* MLcad time: ~50 hours
Challenges in this project:
The power XL motors are very very strong!! Therefore, it took a while to develop a driving gear which will not end up with 'jumping gears, bricks and axles' when more friction comes into account by driving 'up-hill', or by 'steering' to left/right with just 1 running track. Due to the powerful motors, it was not possible anymore to have a loosely coupled undercarriage at the rear side for raising/lowering.
A couple of functions
are 'packed together' in the same area of the model:
1) The 2 pneumatic cylinders to raise / lower the front part of the groomer.
2) The medium motor to operate the front tiller (between the 2 pneumatic cylinders).
3) The only place of the battery box was behind the driver seat and as low as possible (because of the weight of the battery box, and the fact that the infrared receivers must be able to fit above the battery box). And important, the battery box should be able to remove easily for switching batteries. This can be done by flipping the seats to the front.
4) The V6 engine, which is above the 2 pneumatic cylinders.
Another challenge was the construction of the undercarriage, the first model did bent to much when lifting the groomer. This was solved by making the undercarriage in such a way that the weight of the groomer is applied 'between' the 2 parallel tracks on each side.
The most front and rear gears (black gears) are connected to the main chassis of the model and are not tight connected to the undercarriage (yellow gears), because of the ability to lift the groomer. As such, the outside of the front and rear black gears bend towards the undercarriage when the tracks are moving. To overcome this problem, the front gears do have shock absorbers to keep 'tension on the tracks'. The rear gears are 'loosely coupled' to the undercarriage with a silver flexible tube 2L / 4L axle.
Drum winch equipment:
Snow groomers do have occasionally a drum winch which is used to anchor the snow groomer on - for instance - a concrete block when crawling very steep slopes. The Prinoth Leitwolf can be equipped with a drum winch and is able to anchor itself over 850 meter distance.
The drum winch can be added after
completing the loading platform model, because the mounting bricks are already
added in this model.
Please take care when leading the wire over all the 'center groove wheels', especially the last center groove wheel before the hook. There, the wire must led between the center groove wheel and the 'gray technic pin long with friction'. As such the wire is locked in a 'vertical' position.
Technical inside (cut-away render):
Ability to select 3 driving speeds!:
It is possible to change the driving speed of the Prinoth Leitwolf NT snow groomer by applying another set of gears within the 'driving train'. This must be done when building the model, and is not easily possible afterwards.
Standard the 'slowest' driving speed is used within the MLcad files, because this gearing delivers the most power to the tracks for crawling steep slopes. But you can change this according to the picture at the right.
- Slow (and powerful). Standard within the MLcad files.
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