Oil-Electric Engines for "Dora", The History of the V 188

The German High Command (OKH) gave as assignment to the firm of Krupp of Essen in 1937 to develop a giant gun, which had to be able to destroy the strongest fortresses known at the time. The gun also had to be able to fire from long distances to keep it out of reach from enemy artillery. The gun had to be able to penetrate concrete emplacements of the strongest type of the time with 7 meters of steel reinforced concrete and also armoured plate of 1 meter. The range had to be 35 km’s and with a lighter high explosive shell 45 km’s.

The calculations made by Prof. Dr. Ing. Erich Muller of Krupp gave a calibre of around 80 cm’s, a weight of the projectile of around 7 tonnes and a barrel length of about 30 meters. Such a construction would cause a total weight of the gun in firing position of over 1000 tonnes. This could only be achieved with a railway gun that had two parallel tracks to divide the weight. The gun could not be transported in this way, for transport various heavy railroad cars had to be used. The gun had to be assembled in the firing position as the barrel could only be moved in a vertical way, the horizontal movement had to be achieved by a curve in the railway track, in which the gun had to be moved inch-wise.

The giant is considered to be the heaviest gun used in WW2. Not only to move the gun in it’s firing curve, but also to equip the various electric and hydraulic mechanisms used from hauling the ammunition to moving the gun vertically with energy, special equipment was necessary, amongst which a new railway engine.

Krupp developed for the giant gun, that was designated "Dora" E (E= Eisenbahngeschutz = Railway Gun) but was also called "Schwerer Gustav", a new oil-electric engine, in which the oil-electric engines had a two-fold function : to move the gun in it’s firing curve but also to move the heavy transport cars during the construction of the gun : in the firing position the motors acted as outside power units for the giant gun. Another advantage of the engines was that they did not betray their position with smoke and steam and could be used in a rather inconspicuous way.

DORA

The Wehrmacht had planned to have 3 Dora guns built. For each one of these two engines were planned, that consisted of two parts. They had the designation D 311 and the parts were designated "A" and "B".

Late in Autumn 1941 the first engines : D311.01 A/B and D311.02 A/B appeared on the gun range at Rugenwald. Before this the not totally completed Dora had already been successfully tested on the gun-range at Hillersleben, to establish if the penetrating power was sufficient. On a little hill a kind of platform was built on which a concrete plate of 7 meters as well as an armour plate of 1 meter was placed. With an almost vertical barrel and a special driving load the targets were penetrated.

At Rugenwald the giant gun was ready at the beginning of 1942 only a few more test shells were fired at the gun-range, everything functioned properly. General-Fieldmarshal Von Manstein, who commanded later the assault on the sovjet fortress of Sewastopol at the Crimea, mentioned the original mission for the Dora the French Maginot-line. Other historians mention however an assault on the fortress of Gibraltar. It is doubtful if already in 1937 use in Eastern Europe had been planned. It is true that at Rugenwald numerous exercises were made in changing the heavy transport cars from narrow to wide railway gauge, but it is possible that this was with view on the wider Spanish railway track.

In Spring 1942 when the Heavy Artillery Unit (E) 672, reorganised from a battery, went on the March from Rugenwald, the western front and Gibraltar were n o longer objectives but the German offensive in the Crimea was halted, and Sewastopol was in Russian hands. A first test at the front would be at that place.

The engine driver was Franz Vokl from the town of Kempten, along Gotenhafen ­ Bromberg ­ Krkau ­ Lemberg ­ Nnjepopetrowsk ­ Saporoshje en Melitopol the broken down Dora" rolled on railway track that had already been changed to Western European gauge.

At first Simferopol was the target, it was reached on 25^th April 1942. During the fight for Kertsch a retreat was made to Taschlyk-Dair on the North of the Crimea for about two weeks.

At last the gun train reached as second train Bachtschisarai, 5 railway stations from Sewastopol. Here some thousands of men had already made a trench in a little hill, had constructed a switching point between the railway track and the gun emplacement and had constructed the firing curve.

The commander of the unit was Lnt-Col Dipl.Ing. Dr. Robert Bohm from the town of Stadtamhof near Regensburg. In an article on Dora after the war he writes about the assembly of the Giant Gun at Sewastopol as follows :

A single railway track was connected to the railway with a switch-point, it was made into double tracks by means of another switch-point. The double track was intended to assemble the gun. At the beginning of the double track another two parallel tracks were connected with switches, to enable the two railway cranes to do their job. The assembly-track consisted in this way of 4 parallel tracks that had very closely spaced sleepers to be able to withstand heavy pressure. The assembly took place with the help of two special double engines of 1000 hp.

1. On the double track the left and right half of the chassis were driven. Each half consisted of four five-axled boogies that were connected in twos, by beams in bearings. The assembled gun moved on 40 axles or 80 wheels.
2. The two assembled cranes were driven on the outer tracks.
3. On the first transport wagon the connection between the left and right part was brought in. It also embodied the mounting for the gun. It was placed with the help of the cranes.
4. On the second transport wagon the gun-cradle was brought in and was connected with the mounting.
5. On the third wagon the gun mantled was brought in and the fourth wagon brought the two parts of the barrel, that was placed in the mantled after having been assembled.
6. The fifth wagon brought the breech-block, after this the main parts of the

After this only ladders and platforms for the crew and elevators for the ammunition (two - one for the projectile another for the cartridge) had to be placed to make the gun ready to fire.

Everything was driven electrically; the horizontal movement was achieved by movement through the curve.

The assembly of the gun took three days. Before this however the railway track had to be laid, which took dependent from the conditions of the country some 3-6 weeks.

The crew that assembled the gun was about 250 men, mostly technicians on railways and electricity. The total crew needed to put the gun into a gun emplacement, ready to fire, was over thousands of men.

The gun emplacement was not only splendidly camouflaged but also surrounded by barbed wire and guarded by special units with dogs. In this way the Giant seems to have escaped the attention of the sovjet reconnaissance because during the total use of the gun during the bombardment on Sowastopol no enemy attack on it took place.

On June 2^nd 1942 the firing on Sewastopol started: to move the gun in the firing curve an engine was used on each one of the tracks, the two engines were coupled with a cable and were driven by the engine driver Vokl, who had only the help of a Russian "Hilfswilligen" (someone who wanted to help the Germans). The engine was constructed so that as to be able to move inch wise with a very low speed and still being able to develop a large power. One of the constructors of the gun mentioned that it has had an own energy plant and each of the boogies a driving unit. During a lull in battle the engines were stationed very well camouflaged in an orchard.

Now and then other assignments were ordered for the engines. One time when the railway station of Bachtschisarai was full of wagons and the small engine stationed there could not fulfil the job engine driver Vokl cleared the situation with the D311 in a short time. Also the engine drove with three wagons to two railway stations to the South to the station of Belbek to get

For the drive from Rugenwald to the Crimea steam engines were used, mostly Prussian G10. The oil-electric engines were not used to spare oil, but were towed to their destination.

In the battle history of the Heavy Artillery Unit (E) 672 it is stated : 1.4 to 1.6 1942 siege if the fortress of Sewastopol. 2.6 to 4.7 1942 capture of the fortress ; 5.7 to 8.7 1942 consolidation of the fortress and the coast artillery ; 15.7 to 20.12 1942 battles Army Group North (near Leningrad) and 21.12.42 ­ 01.06.43 battles near Nowgorod.

The fortress Sewstopol surrended after heavy fights in the first days of July 1942. The Dora was unassembled soon after and was moved from Bachtschisarai to the northern part of the eastern front. A major attack on Leningrad was planned, for which as in the case of Sewastopol all heavy artillery was concentrated. In the surroundings of the railway station of Taizy some 30 kms of Leningrad the Dora was put into firing position as it had been near Sewastopol. It was fully operational when the attack was cancelled.

A new assignment did not follow. The engines were stationed near Wolosowo at Donzy south of the railway Leningrad-Narva-Reval. In the winter of 1942/43 they must have been there, snowed until the roof. One of them returned to Germany during the war, It survived the defeat at Krupp, Essen.

The gun must have been returned to Rugenwald.

John L Rue