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Saturday 31 December 2011

Westleton 30.12.2011

Spent yesterday mapping at Westleton. By the end of March I hope to have the main Kruschen site mapped at Westleton so may be able to start  making some sense of the data collected so far. However I will probably not have time to map the bit of the Kruschen site remaining at Dunwich. There will also be mapping to complete at Westleton in areas not part of the Kruschen site.

Three features of some curiosity mapped today.

Firstly  three pits created by deepening an existing old boundary ditch. I am not sure of the age of the boundary ditch but it is certainly not any time recently!

Above: Map of a crawl trench system along with three pits dug by deepening an existing boundary ditch (shown by the dotted line). The crawl trench is of interest in that its is the first I've seen which incorporates a V shaped weapons-slit. Photo shows pit dug in existing boundary ditch.

Secondly a series of slits dug alongside the anti-tank ditch.

Above: Plot of slits alongside the anti-tank ditch. Photo shows one of the slits and the anti-tank ditch. This section of the ditch was not dug as part of Kruschen but was excavated in early 1941 and ran from Minsmere to Dunwich.

Thirdly, when I went to map what I thought were only two slits that I had found previously, I ended up mapping 21! It just goes to show how easily they can be missed and the value of repeat visits. What puzzles me is the layout - I cannot see what it was hoped to achieve in training with them (except possibly just giving troops a chance to dig a 6 ft X 2 ft slit). They are way too close together to represent any kind of unit defence post or even for PAD. The ground was certainly shelled during live firing exercises (as the shell fragment shows) but presumably not when these slits were being dug! This is going to be the biggest headache when it comes to making sense of the data - deciding which earthworks were part of Exercise Kruschen and which were not. For the vast majority of the one or two man slits I've mapped to date, it will probably not be possible to come to a conclusion! Even so I think it still of value to map what is in effect the remains of a major training area, more or less undisturbed since the end of the War.

Above: Plot of 21 slits, which I can make no sense of the layout. Two photos show my bag in one of the slits, showing just how well preserved some of them are. Last photo shows a fragment of shell, indicating live firing in the area.

Finally thanks to all who have viewed the blog / website (which has now had 21,000 hits!!) and wishing you all the best for the New Year.

Thursday 22 December 2011

WW2 Mechanical Earth Moving Equipment - Part 3

Either the weather or other things have prevented me from getting out and recording in the field so it's  a good opportunity to post Part 3 in the Earth Moving equipment thread.

This post will concentrate on some of the attachments for the base RB machine used by the Army for defence works etc. 

This was considered to be the most universal equipment. It consisted of a long boom, or jib, and specially designed drag bucket. It is not positive in action but is rapid in operation. It requires a great deal of skill to operate. 
The bucket is thrown (or cast much the same way as in an angler casting a fly) by swinging the jib with the bucket held well up. The hoist and drag ropes were released allowing the bucket to fall forward of a vertical line from the top of the jib. The swing of the jib was checked at a point in line with the fall of the bucket. The drag rope was wound in dragging the bucket forwards to the base of the jib.
It could only be operated in soft materials and was ideal for dredging under water. This equipment would certainly have been used to widen and deepen existing ditches on Suffolk's coastal marshes to from anti-tank ditches. It may well have been used for digging anti-tank ditches elsewhere as well, much of the soil along the Suffolk coastal strip being sandy. 

Back Actor
This consisted of a digging shovel, downward and backward towards the machine, similar to the drag line but was positive in action.  The bucket was attached to a bucket or dipper arm, which was mounted on a stout boom.  The forward edge of the bucket is fitted with teeth and side cutters.It could be used to dig deep trenches or pits and can operate in fairly hard soils but it was not as rapid as the Dragline. This equipment may also have been used for anti-tank ditch construction in Suffolk although I have as yet found no specific reference to its use.

In Sept 1940 135 Excavator Coy R.E carried out experiments using excavators (Back Actors) to dig down to unexploded bombs.For example a 50 kg bomb buried 12 1/2 ft in clay was excavated, brought to the surface and defused in two hrs by 135 Coy; it would have taken five men with picks and shovels approx  two and a half days. Chief Engineer GHQ recommended that sub-units consisting of one Dragline and one Back Actor be employed for bomb disposal. Twelve sub units were required by Oct 31st of which six were required by Eastern Command. The War Diary of 135 Coy would suggest that Earth Augers were eventually used for bomb disposal works rather than Back Actors.

This equipment was used for excavating material at or above the level of the base of the machine. It could cut accurately within fine limits. It consisted of a short boom and bucket. The bucket is open at the forward end. The bottom is hinged at the forward end and secured by a trip at the rear. The bucket slides forwards and backwards along the boom on rollers. It is operated by lowering the boom to the digging position. The drag rope was then taken up drawing the bucket forward along the boom into the soil, filling the bucket. The bucket was emptied by operating the trip, allowing the bottom of the bucket to fall open on its hinge.

Monday 12 December 2011

WW2 Mechanical Earth Moving Equipment - Part 2

This post will look at the excavator. The base machine built by Ruston Bucyrus was the standardised  machine  used by the British Army during WW2. The normal base machines used were:

10 Roston Bucyrus
19 Roston Bucyrus
22 Ruston Bucyrus
37 Ruston Bucyrus

The RB 10 and RB 19 were normally employed in the field due ease of mobility. The RB 22 and 37 were considerably heavier and required special transport to move.

Above: Roston Bucyrus 19 Base Machine

All were powered by a diesel oil engine. The RB 19, 22 and 37 were started by compressed air - a small petrol driven donkey engine operating a compressor. The RB 10 was equipped with an electric self-starter assembly.

10 RB
Type of Engine: 3 VRON
Horse Power: 30
Weight of Base Machine: 9 tons
Ground Pressure lbs./sq.ft.: 1,440
Rated Capacity of Bucket: 3/8 cu.yd.

19 RB
Type of Engine: 3 VRON
Horse Power: 55
Weight of Base Machine: 17 tons
Ground Pressure lbs./sq.ft.: 1,650
Rated Capacity of Bucket: 5/8 cu.yd.

All the machines were fitted with three rope drums, or winches, which operated the jib or derricking rope, hoist rope and drag rope. Interchangeable front-end equipments were available for the base machines enabling the unit to be used for a variety of purposes.

Transporting Excavators
The only trailer normally available for the movemment of excavators was the Roston Bucyrus Trailer. It would take a load of up to 20 tons. It consisted of a triangular girder frame fitted with a removable platform. The front wheel assembly was detachable allowing the apex of the railer to be lowered to the ground. The usual prime mover was an A.E.C Matador or Scammell.

To transport excavators, the platform was removed and the front wheel assembly detached. A timber ramp was put in place  allowing the excavator to travel onto the trailer. The apex of the frame was then jacked up allowing the front wheel assembly to be slid back into position. With the platform in place the trailer could be used to tow any size tractor as well.

Above: Top - Excavator mounting trailer ramp. Bottom - 19 RB mounted on RB trailer attached to prime mover.

Subsequent posts on this thread will look at the various front-end equipments available to the base machine - dragline, back actor, skimmer and face shovel