Prinoth Leitwolf (2006 - 2007)
After finishing the 8421xl, I recognized a new challenge during a ski holiday in Söll (Austria), a snow groomer based on the Prinoth Leitwolf. The main reasons to build the snow groomer is based on the many technic functions, and the fact that I never saw a snow groomer in technic before.
The first model is constructed around the (now) 'old' technic tread (# 3873) and called therefore 'Prinoth Leitwolf OT' (Old Treads). These treads do have there limitations (strength, size) and I was happy The Lego® Company launched a new tread recently (# 57518). A logical step was to improve the snow groomer with the new treads.

Web-page of the 'new treads and Power Functions' groomer:

Prinoth Leitwolf NT

At this moment, you will find on this page all the MLcad files to build the Prinoth Leitwolf model, based on the old treads. I hope you enjoy it.

Notice that the model can be build in 2 designs:
* with loading platform only
* with drum winch equipment 

 

 

 

 

 

 

 

 

 

 

 

 

 

The technic specifications of the 'Prinoth Leitwolf OT' model are:
* Independent track movement, powered by 2 electro motors
* Working V6 engine
* Undercarriage height adjustment (front & rear side)
* Pneumatic front blade & rear tiller
* 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
* Chair back rest movement to front & back (access to pneumatic switches)
* 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 OT (with drum winch) are:
* Length: 51 cm
* Width: 24 cm
* Height with lowered undercarriage: 20 cm
* Height with raised undercarriage: 21 cm
* Height adjustment: 1 cm
* Weight: 1,7 kg    

* Number of parts:
     * with loading platform: 2324 (including crawler tracks)
     * with drum winch: 2580 (including crawler tracks)
     * crawler tracks: 360 treads

* Development time: 175 - 200 hours
* MLcad time: 50+ hours

 

 

 

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.

 

 

Undercarriage lift mechanism and tread drive shaft:
One of the first challenges to solve was the undercarriage lift mechanism. The Prinoth Leitwolf can lower of raise the middle undercarriage ('big gears'), depending on the circumstances (slope angle, snow conditions), which will result in more or less grip on the snow surface.

The mechanism is performed by driving two booms (front and rear) which 'pushes' the undercarriage down or 'pull' the undercarriage up. To make this possible, the undercarriage is 'loosely coupled' with the main body of the snow groomer.
The two booms are operated with the two black knobs at the roof of the cabin.


Another challenge which keeps me busy for hours was the tread drive shaft. The reasons were twofold:
1) I did want to place the electro motors a little high on the chassis to avoid contact with the snow (snow is wet and not very good for the motors).
2) The drive shaft must drive the rear small gears (like the original).

So, a special construction was developed with a worm gear and two universal joints to operated the tread drive shaft at the rear side of the groomer.

 

The small pictures show the different positions of snow groomer. Take a close look to the position of the small 24 tooth gears compared to the 40 tooth gears.

The pictures show (from left to right, up to down).
1) Front side raised
2) Rear side raised
3) Both sides raised
4) Both sides lowered

 


Pictures were taken in Les Arc2000, France.

 

 

Electro motors and V6 engine:
The original Prinoth Leitwolf does have a hydrostatic system powered by a V6 engine. The hydrostatic system is used to drive the crawler tracks and other equipment such as the front and rear tiller.

In the model, each track is powered by an individual electro motor. To prevent the electro motor from stalling, a 24 tooth gear clutch is used. Don't expect the snow groomer to crawl slopes, because the power of the electro motors (# 71427) is not sufficient. These motors will be replaced with the electro motors of the Bulldozer set (# 8275), which are expected to be more powerful.

The V6 engine is driven from the left electro motor, unfortunately there was no space left for a differential between the two electro motors.

 

 

 

 

 

MLcad files:
The Prinoth Leitwolf OT is made up of several sub models within just one mpd file, except for the drum winch which has it's own mpd file.

   

    MLcad files zipped with WINrar

The following MLcad files are used:
* Prinoth Leitwolf OT.mpd                                            
        Snow groomer (main model)_s.ldr
        Cabin back.ldr
        Cabin front.ldr
        Cabin window and roof.ldr
        Chair.ldr
        Door mounting bars.ldr
        Electro motors.ldr
        Electro motors roof.ldr
        Engine roof.ldr
        Engine V6.ldr        Mirrors.ldr
        Rear tiller.ldr
        Right worm gear mechanism.ldr
        Side and engine skirts_s.ldr
        Snow flap.ldr
        Tread guards.ldr
        Undercarriage.ldr
        Undercarriage lift mechanism.ldr
* Drum winch.mpd
        Drum winch assembly.ldr
        Drum frame.ldr
        Drum boom and hook.ldr
        Platform modified.ldr
* PL OT pneumatic help.ldr

 

MLcad unofficial part list
Please navigate to the 'MLCad parts library' page on this website if you having trouble with the correct reflection of the *.mpd and/or *.ldr files within MLCad or LDview.

Probably you do miss some (or all) unofficial parts I did use within the model.

 

Flexible part list
All the flexible parts used in MLcad were generated with the Lsynth tool. As you might know, flexible parts are generated of many small (none lego) parts. Therefore, the MLcad part list for the flexible parts is not correct. The following flexible parts are used within the Prinoth Leitwolf model.
* Pneumatic tubes
        Pump: 1x 7 cm black
        T-bars to switches: 2x 3 cm black
        Front cylinder: 1x 14 cm gray (bottom) & 1x 18 cm black (top)
        Rear cylinder: 1x 35 cm gray (bottom) & 1x 31 cm black (top) 
* Flexible tube:
        Between gas cylinder & tap in the engine room: 1x 9 cm black (same tube as in the Auto Chassis 8860)
* Flexible axle:
        Loading platform: 2x flexible axle 11 black (# 32199)
* Ribbed hose:
        To rear tiller: 2x ribbed hose 11L metallic silver (# 78)
* Electrical wire: 2x (and two battery packs, which are 'hidden' in the MLcad files)
* Drum winch wire: 2,5 - 5 meter

 

MLcad building instructions:
The following information will help you to build the Prinoth Leitwolf model without to much trouble.

1) Technic models nowadays uses frequent 'mounting axles' which must be 'pushed' into a sub-model part which was build separate. Within the MLcad files, these mounting axles are already in 'pushed' position. Keep this in mind when you want to mount individual sub models (especially when connecting the undercarriage).

2) The first step to take is to 'export' all the sub-models of the .mpd file into one directory. This gives you the opportunity to load every sub-model into the LDview program, so you can take a close look to the sub-model from every perspective.

3) Start to build all the sub-models BEFORE starting to build the 'Snow groomer (main model)_s.ldr' file. This file starts with the main chassis of the snow groomer, but acts as an assembly file for all the other sub-models as well.
The same procedure is applicable for the 'Drum winch assembly.ldr' file.

4) All the sub-models can be placed as 'one unit' on the snow groomer model, except for the 'Cabin window and roof.ldr' and 'Side and engine skirts_s.ldr' sub-models. These sub-models have to be partly 'broken apart' to be able to connect to the main model. Another way is to build these two sub-models from the scratch 'around' the main model.

5) Connect all the pneumatic tubes directly to the pneumatic cylinders, switches and pump when you place these parts. Otherwise you will not be able to connect them later on. REMARK: the pneumatic tubes for the rear tiller must be lead through three technic 1x2 brick 'with holes' and two fences'.

6) For a better view for positioning the pneumatic tubes, notice the 'help' file: PL OT pneumatic help.ldr.

7) Notice that the undercarriage does have a front and rear side. The front side is the side with the 1x1 red tile on each side. These tiles are necessary to prevent the front gear (24 tooth) suspension of the main model from distortion when driving.

8) Notice that the loading platform is modified for mounting the drum winch. This platform modification is found in the 'drum winch.mpd' file.

9) Take a close look to the drum winch file when you place the wire. On the frame, the wire should led - seen from the drum -  as follows: over the first 'center groove wheel', under the second center groove wheel. At the end of the boom, the wire must led between the center groove wheel and the 'gray technic pin long with friction'. As explained, the drum winch is mentioned to lock the snow groomer to a concrete block on steep slopes, and not for lifting. This means that the wire is in a 'vertical' position when in use.

10) The reason why the hook does have two yellow 'technic bush 1/2 smooth' is that in this case it is possible to attach the wire exactly in the middle of the hook.

 

Child modifications
From my own experience I do now that kids love the snow groomer. Mostly, kids do not want to operate the electro motors. If they want to push the model just by hand, remove the two worm gears at the rear side of the snow groomer. This can be easily done.

 

LDview:
Version 3.0 of LDview will give the correct 3D views of the Prinoth Leitwolf. Previous versions had problems with multiple ldr files loaded into one mpd file.

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