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.
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.