Differential fluid

Forum for discussion relating to the Sdkfz 222
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Ad Wouterse
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Post by Ad Wouterse » Sun Jun 01, 2008 11:22 am

Hi Lawrence,

That's the way to go :wink:
Just top it up and turn the bottom shaft slowly and very very carefully. Then let it sink in for 10-15 minutes while still open, add some more fluid if required and put the lit on.
Please keep us updated on how it works.
Cheers,
Ad

Lawrence Godson
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Location: Westchester, suburb of Chicago, USA

Post by Lawrence Godson » Tue Jun 03, 2008 2:17 am

I've been delayed--real world getting in the way! Will let you know when I make progress again.
Lawrence Godson

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Patrick O'Donnell
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Post by Patrick O'Donnell » Fri Jun 06, 2008 8:56 pm

Dear all,

Have you used steam oil in your diffs. yet?

It is available in several amounts of thickness, from sticky as golden syrup to as solid as frozen butter.

Mark and Gill might be able to supply the super, sticky, solid, stuff as they used to make large scale steam locomotives in the olden days?
Patrick
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Rene, "Would you like a ride in my little tank?"

Lawrence Godson
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Location: Westchester, suburb of Chicago, USA

Post by Lawrence Godson » Tue Jun 17, 2008 8:05 am

Finally got things back together and ran the 222 on some uneven ground with the new 100,000 wt silicone fluid (packed in tightly this time) in the center Diff... Much improved!--- no stalling unless one tire from both front and back looses traction. Thanks to all for advice.
Lawrence Godson

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Ad Wouterse
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Post by Ad Wouterse » Tue Jun 17, 2008 11:15 am

Hi Lawrence,

Good to hear that the performance of your 222 has improved this way.
We have to bear in mind that we are talking about 1:6 scale vehicles, so the obstacles in the terrain should be considered in the same scale.
More improvement is still possible, but do we want that ? :roll:
Cheers,
Ad

Lawrence Godson
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Post by Lawrence Godson » Wed Jun 18, 2008 2:22 am

It would be interesting to hear first hand-either from Littlefield's people in California (the only surviving 222 that I know of) or if any actual WWII drivers of 222's are still around---just what were the characteristics of the differentials over rough terrain.
Lawrence Godson

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Ad Wouterse
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Post by Ad Wouterse » Wed Jun 18, 2008 9:10 pm

Lawrence,

The original 222 was designed primarely as a road vehicle with only limited off-road capabilities. The high center of gravity, the special type of suspension necessary to allow the weight of the armour and the unfavourable weight to wheelbase ratio all point in that direction.
The drivers instruction manual was quite clear about the special handling required by this vehicle. Special attention had to be paid to driving through turns, steep climbs and higher speeds. Rough terrain in general and crossing ditches in particular should be avoided as much as possible.

I think that it is only fair that our 222 model should be seen for what it is: not an off-road buggy or truggy but a historically correct RC model of a WW II vehicle. And in my opinion that is what Armortek was aiming for when designing this model.
Cheers,
Ad

Lawrence Godson
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Post by Lawrence Godson » Thu Jun 19, 2008 5:58 pm

Probably all true Ad. It would still be interesting to get first hand info on whether, for example, the front and back Diffs. are "limited slip" or not.
Lawrence Godson

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Ad Wouterse
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Post by Ad Wouterse » Thu Jun 19, 2008 10:20 pm

Hi Lawrence,

According to my sources the original 222 had following lay-out :

- standard 2 wheel drive (rear) with full lockable diff
- optional 4 wheel drive through manually operated interlocking centre drive shaft to front diff.
- full lockable front diff.
- standard 2 wheel steering (front)
- optional 4 wheel steering through manually operated interlocking shaft/rod

The original vehicle had no centre diff.
I can dig up some pictures if you like.
Cheers,
Ad

Lawrence Godson
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Post by Lawrence Godson » Thu Jun 19, 2008 10:51 pm

OK so they could lock the front and rear wheel Diffs. Interesting! Then with both front and rear locked and 4 wheel drive engaged they would have full power to all 4 wheels at all times no matter if one or more wheels lost traction? I assume they could lock the Diffs. from inside the vehicle?
Lawrence Godson

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Allan Richards
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Post by Allan Richards » Fri Jun 20, 2008 9:19 am

Lawrence,

As well as the locking diffs another factor with the model is scale weight. For the Tiger tanks I have assumed that weight scales as a cube of scale. For the tiger this is 6x6x6x weight of model in pounds (350lbs for my tank) This equals 75,600 lbs, whereas the fighting weight of a Tiger is 125,400 lbs. which makes the models lighter than scale. This is not surprising with the tanks as they use aluminuim for the hull, turret and tracks plus there is no interior as such. I am sure if you do this excersise on the 222 you would find the scale weight quite light. If the model is only half the scale weight it will effect grip quite a bit. Equally doubling the weight with balast would knock performance.

If you want good climbing and off road performance I think you will have to lock the diffs. I don't think you will loose any performance, maybe just a bit of turning circle on slippy surfaces.
Allan Richards

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Ad Wouterse
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Post by Ad Wouterse » Fri Jun 20, 2008 8:10 pm

Lawrence,

The diff locks could be engaged from the drivers position. The vehicle should be stopped before locking/unlocking. 4 Wheel drive was to be used only under extreme terrain conditions and at low speeds.

Allan,

I am very sorry, but I tend to disagree with your proposal. Permanent diff lock will definitely improve the terrain performance, but for how long ? The strain on the drive train will be enormous, especially in combination with increased speed and the weight of the model. On the old forum Mark warned us for this.
The 222 model suffers from overweight :shock: . When I use your calculation method on my 222 ( 28 kgs), I get a weight of 6048 kgs. for the full scale. In reality the max weight was just below 5000 kgs.
Cheers,
Ad

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Allan Richards
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Post by Allan Richards » Sat Jun 21, 2008 9:51 pm

Ad,

Locking the diffs comes from personal experience. I've made a 1/12th scale DUKW that originally had diffs but I could never get the traction to get the model out of the water, one wheel would always slip on each axle. I ended up locking all the diffs and didn't notice any real handling problems or over stressing of the transmission. This said the model is a lot lighter than the 222. If the full size vehicle could lock its diffs and didn't have a centre diff then that is how it got its off road capability,

The equation for weight is only very rough but I forgot that the 222 model has a steel hull and I suppose that the battery and motor are a larger proportion of the total model weight making it appear a heavier than scale weight.
Allan Richards

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