Sir John Valentine Carden survives.

Can any one explain why tanks in WW2 seem to be front wheel drive? I would have thought rear drivers would gave made mor sense
Front drive, rear engine has better weight distribution, and far easier to work on.
Rear drive, rear engine is compact, but can have difficulty with controls. Without power assist, you get example like Soviet drivers needing a hammer to aid in shifting gears
 
Germans were pretty effective in making all the Channel ports unusable through mass bombing raids - at least for the duration of the evacuation. You'd need a much better performance by the RAF to keep any of the ports open for longer than a day or two more.
IIRC, OTL the Germans bombed and shut down the port of Dunkirk early in the evacuation, and the British were reduced to improvised jetties on the beaches, or small craft ferrying men to ships offshore. It was only a day or so later that they realised that the East & West Moles - which were breakwaters not intended for docking ships - were still usable and started picking men up directly from there.
 
One disadvantage with the front-drive idea is having the drive-shaft running through the cabin. You also have to compromise on either maintenance accessibility (as the Germans did), or armour weight (as the Americans did).
 
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Ramp-Rat

Donor
The Evacuation.

The Evacuation of part of the BEF from the Channel Ports in 1940, was a magnificent example of British making it up as you go along. Unlike Gallipoli during WWI, which was planned for or Hamgham during the Korean police action, where overwhelmingly American air power and naval forces, prevented the North Korean forces intervention. This evacuation was very much done on the fly, planned on the back of a fag packet with a pencil. And while the French whose ports were being used, were not consulted or included in the planning. The commander on the ground made the decision to evacuate before he told London, and started the process, then London had to play catch up, and put in place the facilities to carry out the nonexistent plan. All this was done while the British PM, was trying to bolster the resolve of the French and keep them in the war, but what was I believe the first example of shuttle diplomacy.

Let us know look at what happen IOTL, and what we can assume is going to happen ITTL. First of all let’s dispel some of the myths around the Dunkirk story. The little boats, while a magnificent example of British improvisation, didn’t play a major part in the evacuation, the vast majority of men were evacuated by the RN and French Destroyer Fleet, the British cross channel and inter island ferry fleet, and the Merchant Navy. Nor were the majority of the little boats maned by their civilian owners, they were maned by RN personnel, taken from shore bases, or off ships in docks. Dunkirk wasn’t an event that can be seen in isolation, there was as much improvisation in Britain as across the Channel. And it involved the whole nation, not just the Channel Ports.

So how does a soldier get out of Dunkirk and back to Britain, and once there what happens to him, and at this time, other than a few nurses it’s a him. The majority of women who got out of Europe , came from other ports and were ether refugees or British expats. There are three ways he can get home, up a gangplank onto a ship in the harbour, across a plank/ladder onto a ship off the East Mole, or by wading into the sea of the beach, being dragged over the gunwale into a small boat, then from there straight home, or by transferring up a rickety rope ladder onto a ship. The first is easy and provided he has his personal equipment with him, will enable him to carry it and any personal weapons, possibly even squad weapons with him. Squad weapons such as mortars, medium machine guns, any thing that is man portable. Off the East Mole, again provided he has it with or on him. Personal equipment and weapons, but not squad weapons, unless he is very strong, or the tide is right. Off the beach, he will be lucky to keep his clothes on, and items such as a great coat, would be discarded, along with most personal weapons, officers might keep hold of their pistols. He also might be able to keep his tin hat and a haversack, though this isn’t a given.

The first is reliant on the harbour being kept open, and the ships being able to enter/exit manoeuvre along side the dock, and the cranes being available to place the gangplank/ gangplanks in position. If the cranes are out of action, or there isn’t the dockers/crane drivers to operate them, you are going to have to improvise. ITTL it should be possible to keep the docks/harbour in Dunkirk open for longer than it was IOTL, how much longer is the question. Here we need to diverge and look at the various types of troops, and how they are dealt with. Troops fall into three basic categories, organised, semi organised, and unorganised . Organised troops are in large groups under the command of their own officers and NCO’s, in contact with the controlling authority. Semi organised, are groups that while they might have been separated from their parent unit, are still under the control of their own Officer/Officers, NCO/NCO’s, and can be directed by the controlling authority. The biggest problem is the unorganised troops, small groups, mixed groups and individuals who are not under any command, and are not in contact with the controlling authority. These men are basically a mob, hard to organise, not subject to military discipline or authority, just doing their own thing while trying to survive and get home.

Those few organised troops not needed to man the perimeter and defend the port, provided AA coverage, or supply/medical services. Can be sent under their commanders to the port to embark on the first available transport, and get them out, the semi organised again not needed for duties, can be directed again to the first available transport out. The unorganised have to be gathered together, placed under some form of control and sent to transport for evacuation, this needs large number of Military Policemen, who are directed by the controlling authority, difficult in the present situation. One reason why both Gallipoli and Hamgham worked so well, the commanders didn’t have to deal with a mob of unorganised troops, even though at Hamgham there were large numbers of disorganised refugees, they were controlled by the Military Forces in place. Given that there has been more time than there was IOTL, the British should have had the chance to establish more of a grip on the ground and control the troops better. If more of the useless mouthes have been evacuated, plus those unorganised troops present during the first few days. This will lead to the port being much clearer, and less troops ether hiding out in the town or on the beaches. Provided that the first few days are both better organised and proceed more smoothly, provided that a good relationship with the French can be established, after all its their country and ports. Then there should be less confusion and muddle, and a slightly better result over all, with more personal kit and weapons being retained, and some of the squad weapons making it back to Britain.

Now let’s look at the second part of the evacuation, the part that is very rarely talked about, or mentioned in the popular history of the Dunkirk story, events in Britain. The returning troops didn’t just hop off the boat, jump on a bus, pop home for kippers and tea. A massive effort was put in place, to evacuate the returning troops from the arrival ports in Britain, and ether send them to hospital if needed. In the case of the French, transport them to ports of embarkation in the West, Southampton, Weymouth, Plymouth, feed them before embarkation for their return to France. Over one hundred thousand French troops, passed through Britain, before returning to France. To move these men required as massive effort by Southern Railway, who had to collect them from the British Channel Ports, bring them often via London or Guilford, to lines running down to the west. While at the same time accepting trains from the midlands and west of England from different companies, whose drivers didn’t know the route, collecting returned British troops, to return them to their various depots for processing. Note for train drivers, route knowledge is vital, if they are to know where the signals are, what the local speed limits are and where the various points are. The trains were stacked up on the down line outside the various ports just waiting to be called forward and loaded up. While in the ports a first and basic separation had to be made, to insure that troops were sent to the right depot, where they could be reformed into units, feed and where possible re equipped, before being sent to their final destination. On a personal note, my mother was a young girl at the time of Dunkirk who had gone into hospital for an operation, the Westminster I believe. After the operation she was doubled up in her bed with another young girl, top to tail, to make room for wounded troops, who were put in her ward. She came out of hospital with head lice, and it took her aunt weeks to clean them out of her hair. A feeding station was sent up at Ashford station to provide the troop trains with sandwiches and tea. Maned by local women and provided with bully beef and processed cheese from government emergency stores. This was just one of such feeding stations set up throughout Britain, remember some troops were transported to Scotland, and Wales.

All in all this was a fantastic effort by the British establishment, military and rail companies, supported by the British people.





RR.
 
I think the author's decision on how long Dunkirk port stays open will be a key factor in this timeline. This is strongly dependent on the defence of Calais and the canal lines as until they are reduced it's unlikely Dunkirk port will have prolonged attention from the LW. Two or three days extra will, as RR says, allow the BEF to manage the evacuation so much more effectively and more than that deny much more munitions and materiel than OTL to the Germans
 
One disadvantage with the front-drive idea is having the drive-shaft running through the cabin. You also have to compromise on either maintenance accessibility (as the Germans did), or armour weight (as the Americans did).
Germans didn't do badly with the early tanks, the drive shaft was offset to the side on the Mk II, and against the floor on the III and IV, with adequate access panels. Only the Panther was really poorly thought out for maintenance
 
So how does a soldier get out of Dunkirk and back to Britain, and once there what happens to him, and at this time, other than a few nurses it’s a him. The majority of women who got out of Europe , came from other ports and were ether refugees or British expats. There are three ways he can get home, up a gangplank onto a ship in the harbour, across a plank/ladder onto a ship off the East Mole, or by wading into the sea of the beach, being dragged over the gunwale into a small boat, then from there straight home, or by transferring up a rickety rope ladder onto a ship. The first is easy and provided he has his personal equipment with him, will enable him to carry it and any personal weapons, possibly even squad weapons with him. Squad weapons such as mortars, medium machine guns, any thing that is man portable. Off the East Mole, again provided he has it with or on him. Personal equipment and weapons, but not squad weapons, unless he is very strong, or the tide is right. Off the beach, he will be lucky to keep his clothes on, and items such as a great coat, would be discarded, along with most personal weapons, officers might keep hold of their pistols. He also might be able to keep his tin hat and a haversack, though this isn’t a given.
If the crew (or earlier evacuees) up on deck have ropes handy, they could potentially lower them down to tie to crew weapons, several each for the heavy ones, assuming they're prepared. Not something you'd want to try in a hurry though, or while under fire. And that's assuming those weapons are even free, not on the perimeter.

All in all this was a fantastic effort by the British establishment, military and rail companies, supported by the British people.
Indeed.

Germans didn't do badly with the early tanks, the drive shaft was offset to the side on the Mk II, and against the floor on the III and IV, with adequate access panels. Only the Panther was really poorly thought out for maintenance
Even there though, if they had to pull the gearbox out for some reason, they had to dismantle half the tank to do it.
 
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Even there though, if they had to pull the gearbox out for some reason, they had to dismantle half the tank to do it.
Every nation, except for the US, made differential replacement difficult, or exceedingly difficult, or near impossible, like on the Panther.
only the US mediums and TDs could it be done by a mobile repair unit in under a couple hours
Stuart's were a little harder to work on, and M24 Chaffee gained a nice access plate, even though that compromised protection.
 
Every nation, except for the US, made differential replacement difficult, or exceedingly difficult, or near impossible, like on the Panther.
only the US mediums and TDs could it be done by a mobile repair unit in under a couple hours
Stuart's were a little harder to work on, and M24 Chaffee gained a nice access plate, even though that compromised protection.
Yeah, but with the British and Soviets, you 'only' had to pull out the power-pack, not take the bloody turret off!
 
Yeah, but with the British and Soviets, you 'only' had to pull out the power-pack, not take the bloody turret off!
But those were not really easy access yet, so had to remove armor to get at all the bits. Hatches and panels not quite large enough.
There's good Russian made stuff on restoring T-34s and such.

Could say that the M3 was groundbreaking just for having the easy access doors from the M2 in the rear, and the new front differential cover for easy access.
The M7 Light, that was a boondoggle, did introduce the easy access rails for differential and engine, later used with the Hellcat, probably the best AFV made during the war, from a repair standpoint.
 
But those were not really easy access yet, so had to remove armor to get at all the bits. Hatches and panels not quite large enough.
There's good Russian made stuff on restoring T-34s and such.

Could say that the M3 was groundbreaking just for having the easy access doors from the M2 in the rear, and the new front differential cover for easy access.
The M7 Light, that was a boondoggle, did introduce the easy access rails for differential and engine, later used with the Hellcat, probably the best AFV made during the war, from a repair standpoint.
They didn't get it all right mind. Having to pull the whole engine out just to change the spark-plugs is a bit of a screw-up.

The USA also had the luxury of being able to examine the conflict from afar, where everyone else is up at the coalface (metaphorically), with the enemy capable of bombing their cities, and so, more of feeling of urgency at all levels.
 
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If you could avoid pulling out the rear guard wich was supposed to be 3 divisons from under the french command by the british by london . Gort gave the divisons to the french to be the rearguard on churchills command i think , have the 3 divisons man the defenses ?
I think mainly you would just get more belgian and french evacuaees with maybe few ten thousand brits i guess ?
 
Knock the power out and the derricks and loading cranes stop working. Also, if you paste the ports then the dock workers stay home in their cellars, and whilst the average Tommy is good at many things, they might not be good at loading ships.
The average Tommy does as he's told. It is the Engineers, the sappers who are good at loading ships and if they have sufficient willing hands small miracles can be worked in a very short time. The REME are also very good at such matters as well. Ships have their own derricks and cranes. They can, if rigged properly load heavy things like tanks and other vehicles. The problem is the ships' crews. They will be unwilling to work under attack.
 
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Front drive, rear engine has better weight distribution, and far easier to work on.
Rear drive, rear engine is compact, but can have difficulty with controls. Without power assist, you get example like Soviet drivers needing a hammer to aid in shifting gears
Front wheel drive is inefficient, basically pushing the track under the vehicle. Rear wheel drive is more efficient, pulling the track under the vehicle, so, from the view of mechnical efficiency rear wheel drive wins. As for the ease of work on front wheel drive AFVs let me introduce you to the Panzer III and IV series, small hatches with the upper glacis needing removal for any serious work. Shermans needing the entire transmission cover removed for virtually any work to be done on it's gearbox/transmission. The rear drive systems just need the rear glacis a lighter plate to be removed. I'd suggest there are good reason why rear drive has become the norm on MBTs.
 
Lieutenant Do-it-all draws Webley revolver and suggests cowering crewman thinks again.
Lieutenant Do-it-all is reported to the Military Police for threatening a civilian. Military officers and men are governed not only by military law but civilian law as well even in wartime in a war zone. Civilian ship's crew would be protected by that law and if militant enough, the good Lieutenant could cause the entire ship's crew to go on strike. Diplomacy can often achieve much greater results than threats.
 
Front wheel drive is inefficient, basically pushing the track under the vehicle. Rear wheel drive is more efficient, pulling the track under the vehicle, so, from the view of mechnical efficiency rear wheel drive wins.
exactly how many percent?
As for the ease of work on front wheel drive AFVs let me introduce you to the Panzer III and IV series, small hatches with the upper glacis needing removal for any serious work
Since the III and IV used a clutch/brake differential, the clutches and brakes need far more attention than the US Cletrac, that used fixed geared ratios.
In addition to not losing power in a turn like the clutch/brake setup, needed far less maintenance and need for adjusting
The rear drive systems just need the rear glacis a lighter plate to be removed. I'd suggest there are good reason why rear drive has become the norm on MBTs.


Model showing normal access panels for engine and differential.

Square foot of that rear and top plate is 34 pounds, rear plate 80

Today? once reliable, it's a good plan to have a single module to pull out for quick repairs
Such was not the case yet in WWII
 
exactly how many percent?
The mechanical efficiency varied on different vehicles. I've seen a figure of over 40%.

The T34 can have it's rear plate removed easily. It is surrounded by nuts which is now it is secured. Just as the transmission of the Sherman can have it's front plate removed. However the Sherman's plate is approximately twice the thickness of the T34.
 
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