RS8 is a locomotive with a completely unique appearance, and an equally strange pedigree. Moreover as an antecedent of Cheedale it is entirely proper that it should be part of the collection, though its outline may not be to everyone's taste!
Built originally by Avonside as an 0-4-0ST (Wks No 1913 of 1923) it was delivered to Denbigh Lime & Stone Co., Craig Quarry near Denbigh station. However the quarry closed after a few years and being a member of the Buxton Lime Firms Ltd amalgamation, the loco transferred (after April 1925 but before July 1928) to Tunstead works in Derbyshire which, given that development of the quarry began in 1927, suggests it was there from the beginning of quarrying. At Tunstead it continued to work as a steam loco and there gained the RS8 number. A photo by G Alliez in May 1957 though shows it out of use, with rear buffers and brake weighshaft missing.
In 1959 it taken into South Central Workshops and emerged as an 0-4-0DH. The work was carried out under the auspices of Harry Townley, the works engineer who had trained at Crewe works and therefore fully familiar with railway work. Structurally the large apertures through which the cylinder/valve chests had been mounted were filled, the motion brackets cut off, and the frame lengthened by 13inches. The axles went to Hunslet in Leeds for driving axle crankpins to be shortened and sleeved, and a SCG RF25 gearbox installed on a new rear axle.
At the time ICI (as it had become) were collaborating with ERF at Sandbach on the production of 8 tractor units to haul 50 ton tipper trailers within the quarry. The power unit for these, a Rolls-Royce C6NFL engine of about 150-175bhp, was mated to a Twin Disc CO 100000 converter. The CO, unlike the more common CF, incorporated a freewheel device whereby the drive would disengage itself if the machine tried to run faster than the converter output speed. A ninth power unit was therefore ordered for incorporation in RS8, further adding to its uniqueness.
But the superstructure attracts the most comment. The small, box-like cab features throttle and brake levers at each corner. It is not in fact taller than normal rolling stock (else it would not fit under loading hoppers!) but being well proud of the running plate level, and having a sloping casing section forwards, gave visibility for the driver far superior to most manufacturers products at the time. It was envisaged that the driver would be alone in the cab to prevent his being distracted, but able to drive at any corner. When working under hoppers, there was the risk of the cab rear access encountering stone falling, and to protect it, an unusual covered walkway was incorporated. Following the death of a shunter when he was outside the line of a loco and struck a wagon on an adjacent track, recesses for the shunters were provided at each corner - a feature that Sentinel were incorporating at the same time but not then on most shunters.
RS8 continued in use until superceeded in the 1970s by modern industrials like Cheedale (RS233), when it went for preservation at Dinting. When Dinting was forced to relocate and there was no room for RS8, it was moved to the National Stone Centre near Wirksworth in spring 1992, where they had plans of establishing a demonstration shunting area adjacent to the C&HP, now a long distance footpath. Unfortunately lack of facilities left the loco alone and exposed at the edge of the NSC car park, where vandalism took its toll.
Several attempts to rescue the loco floundered on exactly who owned it. Eventually during late 2015 this was resolved following approaches to add it to Andrew's collection, and by Christmas 2015 it had been agreed by the NSC Trustees that it would be passed over, although formalities had not yet been completed. Eventually, on 10th June 2016, the loco was collected from the NSC and transported direct to Darley Dale, as having not turned a wheel in over 20 years it was considered too risky to unload at Rowsley and tow it southward.
In July 2016 the opportunity of acquiring a C6N-powered genset was taken, with the plan that the engine would provide a replacement for the elderly prime mover in RS8. Outline agreement for apprentices at Tunstead to take part in its restoration was agreed in late 2016. By May 2017 stripping had progressed far enough that Tarmac were able to take the superstructure parts up for shotblasting, returning to Tunstead with original and replacement power units to make a start.
By September, the frame had been taken back to Tunstead, where various bits of corrosion and cracking were tackled in the Sigma6 workshop before the frame would be returned to the original erecting shop where it was rebuilt from steam to diesel. Meanwhile it was discovered that one crankpin was loose in the wheel centre. Tarmac manufactured a new crankpin to suit the boss sizes and this was cryogenically-shrunk for fitting before the wheeelsets go back under the frames. The replacement pwer unit has been serviced, its pump and injectors changed, and run up on its original bed frame before the overhauled torque converter was fitted.
After a break early in 2018, the frame was returned to a building, now the 'Stores' but once the Engineering Works where the loco was converted, and work resumed in earnest. By July the frame had been wheeled, the fuiel tanks, cab, rear sheet, brake rigging and weighshaft re-fitted, and work proceeded on new rear engine mounts in preparation of fitting the power unit back in to the frames. Work proceeded on renewing the vac pipe in galvanised pipe, but re-using a lot of the malleable iron fittings, many of which are no longer available. A new timber cab floor was fitted, and of the loco buffers were stripped, sand-blasted, primed and reassembled.
It had been hoped to reach a running conditioin by late in 2018, but as it came around to Christmas progress on pneumatics, electrics, etc had not quite achieved this. Even little things have succeeded in inflicting considerable delays - for example re-using a distinctive manifold from which various pneumatic functions are fed, turned out to have an obsolete thread form on its delivery side that may yet have to have a specially-machined adaptor. Such is the unforseen problems in restoring even a 'modern' diesel loco.
Historical notes from IRS Pocket Book F: ICI and conversion notes from Derek Burton.
|Original builder (as 0-4-0ST) and works number||Avonside Engine Co, Bristol 1913 of 1923|
|Conversion to diesel hydraulic||1959-60|
|Power unit||Rolls-Royce C6NFL., prob 179bhp at 1800rpm coupled to Twin Disc torque converter series CO 10000|
|Final drive||SCG RF25, axle mounted|
|Weight in working order||23tons|