Could anyone share a detailed drawing of the Porsche wheel trucks as used on the Ferdinand and Jagdtiger .
Specifically the arrangement of the torsion bars and their axle connections.

Thanks ,
Keith

... or the best book for this info ..

OptomisTic fishing bump

You probably know this small drawing already don't you



H.P.

Picture no showing ...

Better now ?



H.P.

I don't have that .

Tells me there is only one torsion bar -- I had inferred that there was two from the text that I have .

I can't read any of that accompanying print ..

Know where I can acquire a readable version

Some pics from Primeportal :

http://data4.primeportal.net/tanks/david_lueck/elefant_spat/images/elefant_spat_60_of_83.jpg

http://data4.primeportal.net/tanks/david_lueck/elefant_spat/images/elefant_spat_70_of_83.jpg

http://data4.primeportal.net/tanks/david_lueck/elefant_spat/images/elefant_spat_72_of_83.jpg

These 1/16th scale parts look to be a good match for the drawing ones :

http://www.rctank.de/bilder/produkte/gross/ELEFANT-FERDINANT-Metalllaufrollen-Federung-und-Antriebs-Leitraeder-in-1-16.jpg

H.P.

Thank you , Frenchy

I'm having difficulty understanding their operation .

The wheels move in an inward arc ?

Maybe this thread will make things (a bit) clearer

http://www.rc-panzerketten-forum.com/wbb2/thread.php?threadid=36688&sid=27efc904f7f680cca0ef29e60a0866bf

I've finally found a period picture :



H.P.

Thank you again , but no .

I certainly see what that builder has done and how those bogies rotate at their mounting .

I don't understand how the longitudinal torsion bar interacts with the axles and what moments this produces

I know the Porsche trucks were rigidly mounted to the hull with 9 bolts ...

I see your edit now with the period photo .

That doesn't even look like the schematic from above .

My brain hurts .

I need to see a design drawing .

I have very detailed drawings of the conical disk bogies that were developed and championed by Lehr so I know that there must be drawings out there

OK -- looking at all of this I have to conclude that the torsion bar interacts only with the trailing wheel.
As the trailing wheel moves up , the support 'tube' rotates at the pivot at the lower end of the support arm . There is some kinda gear at that junction that imparts the twist to the torsion bar.

Then there must be another spring assembly in the mount for the lower section --- allowing the entire bogie to rotate up , to the front .

I need to see a drawing of the attachment .
This is very odd as it doesn't seem to match the text that I've read .
..... other than the system being rejected on the Jagdtiger due to untenable oscillations .

If the mechanics that I described are correct , then I see why it didn't work well .

There are two pivot points. One on the hull where the swing arm mounts. The other runs through the axle of the leading road wheel. The tube carrying the rear wheel and containing the torsion bar articulates around it.

The hull mounted pivot is unsprung. It just carries the bogie and allows it to swing relative to the hull.

The front wheel axle pivot operates a lug and toggle assembly inside the tube. The lug engages the free end of the torsion bar through a toggle and collar, which is splined to the free end of the bar. The torsion bar is fixed inside the tube at rear wheel end.

Look at Frenchy's photo above to see how much beefier the front axle housing is compared to rear axle. This is because it contains the axle wheel bearing and the suspension pivot bearing around it. It also houses the lug that connects to the toggle and collar inside the tube.

The rear wheel articulates around the axle pivot running through the front wheel - this action engages the torsion bar. The front wheel articulates around the hull mounted pivot and its own axle pivot - which engages the torsion bar in opposite direction of twist.

In both operations - front articulation and rear articulation - the rotation moment passing through front axle pivot is what engages the torsion bar. The bar is twisted in opposite directions by the lug/toggle/collar assembly inside the tube at the free end of the bar, which is at the end of the tube near the front wheel. (Note, the rear most bogie was attached in the reverse direction so 'front' and 'rear' wheels are reversed if you’re looking at the third bogie).

It’s a complicated system. It was also highly stressed because the bar is short and the metallurgy of the time didn’t allow for much twisting flex. It was prone to breakage. It also didn’t allow much sprung wheel travel. There was a rubber bump block that was engaged after only a short deflection of the suspension. Once the bump stop was engaged, the system was rigid but still free to articulate around the hull pivot, allowing a lot of unsprung travel.

Contrast the length of the Porsche longitudinal torsion bar with the design solution of the Panther - which used a twin transverse torsion bar system that effectively doubled the torsion bar length to twice the hull width. Panther suspension allowed over 20'' of wheel travel and didn’t overly stress the bars, although it was heavy and complicated.