WW1 supply sledges

[Orso]

I'm building supply sledges to be towed behind a tank but are unsure on how to attach two sledges to each other.

 

 
I can't see this on pictures of the real thing but I have seen a build where the modeller used two parallel chains between the sledges.
But I wonder if this mount wouldn't make them hard to steer an make a strain on the chains.
I would have guessed that a "triangular" mount of the chains would work better? Any ideas on this?

[Black Knight]

A triangle of chains makes the following trailer harder to control and can throw the forward trailer off its tracking. The triangle allows the following trailer to deviate off the chosen course and can pull the rear of the forward one around

The parallel chains keeps the following trailer(s) in line with the main trailer, making them follow exactly behind

With a solid A frame the towed trailer or vehicle is easier to control

 

info based on 'rescuing' fwd and vintage cars out of mud at events

[Kingsman]

For the benefit of the audience on this forum here is a repeat of my post on Missing Lynx.  This thread is running in parallel there too.

 

You are aware that the tanks adapted to tow sledges had the towing point fitted at the back end of the hull roof so that the tow cables would clear the rear tracks when turning?  

The V arrangement between the sledges as in your lower diagram does make more sense.  But in the few available photos they seem to be very closely coupled together, which would suggest straight cables as in your top diagram.  With the large turning radius of WW1 tanks articulation between the sleds was perhaps less important than we think.

This particular photo is interesting as it shows a MkIV with a "tadpole tail" towing 2 sledges.  Said to be just for trials, as the tadpole tail was not deployed operationally.  It proved to be insufficiently rigid and prone to distorting.  The sledges here are further apart than in some other photos.  Annoyingly you can't see the connecting tow cables.  But if you enlarge the photo you can see what looks very much like a vertical eye at the nearest rear corner of the front sledge, right at the outside edge.  That would lend weight to the idea of 2 parallel cables and a straight tow.  But there is nothing like that on the rear sledge.  Was the front sledge perhaps different?


In this view of the back of a 2nd sledge there is no sign of any means of attaching a tow.  Does that perhaps suggest that they came in pairs of front and back versions?


If you want something completely bizarre I give you the Tank Supply Roller.  As the photo shows, it was built - but never used.  In many ways a more sensible idea with much less rolling/skidding resistance.  The supplies were carried in the central caisson, which always remained level and did not rotate with the drum.  No sense of scale but I believe it was about the same height as the tank.

[Orso]

Thanks for the input. I opted for two straight chains

 

[Solexman]

Probably too late on this subject, however it would also be likely the ropes/ chains would cross over between the two sleds.

This configuration would make them stay in line, track better when turning and allow them to be coupled closer together.

Its a common technique when carrying out a tow like this and was used for heavy hauling with steam traction and multiple trailers at the time.

[Orso]

Not too late as I haven't built the tank yet and the chains would be easy to move.

I have been considering the crossed mountings as I can't see the advantage of the parallel mount that I was pointed to in a thread.

I noticed the cross mount when I looked for pictures building a Centaur. I was told that the sledge could slide sideways with the triangular mount but I think that it goes for the parallel mount as well.

 

[Kingsman]

The few WW1 photos show parallel chains/ropes.  Towing any form of trailer was relatively novel in WW1 so they probably had not had the revelation about crossed tows.  Their experience would be parallel tows from horse-drawn wagons, guns etc.

 

I don't know how the Porpoise would behave in a turn, noting that tank turns tend to be more abrupt than gentle.  The rigid tow bars telescoped short on the LCT but pulled out to full length when the towing vehicle moved forward.  Were they able to shorten as the towing vehicle manoeuvered?  You don't want to be trying to skid the sled sideways in turns.  That was the problem with the steering wheels on the MkI tank.  When I see tanks towed today I see A bars rather than X, allowing the tow to pivot.

[Black Knight]

28 minutes ago, Kingsman said:

The few WW1 photos show parallel chains/ropes.  Towing any form of trailer was relatively novel in WW1 so they probably had not had the revelation about crossed tows.  Their experience would be parallel tows from horse-drawn wagons, guns etc.

Not quite. The British Army had plenty of experience of similar towing from the Boer Wars, 1899 -1902

In those wars the British Army used armoured traction engines pulling both wheeled trailers and sledges, often the tows were mixed

[dnl42]

I like your sledges! An interresting and unusual subject and nicely built.

I don't understand the crossed or parallel rigid bars though as they would force the sledge to move sidewards in a turn, which I believe would cause the side to dig in. Parallel chains on a 2nd sledge might work but the outside chain would pull the entire load in a turn. 

[dcrfan]

I agree the cross bars are unusual but I'm not not convinced that they may not be solid given the step-down in thickness at about the halfway point.  Perhaps the inner bar on a turn (on the tank end) can telescope in slightly transferring all pull to the outside bar.

Edited March 8, 2023 by dcrfan

[Kingsman]

The Porpoise bars definitely weren't solid.  They were made of 2 sections of tube allowing them to telescope and extend, so it seems possible that the bar on the inside of a turn would be able to shorten.  But a pivot turn would not be advisable.