The EPVs were phased out during 1950 and replaced with the very successful EVs and later still the E type. These engines would find their way into world-wide applications; ground-base installations (power generation), marine propulsion, and railway locomotives.
Lister Blackstone was acquired by the Hawker Siddeley Group on 1st June 1965 and merged with Mirrlees National of Stockport four years later. The company name was then changed to Mirrlees Blackstone Ltd.
The origins of the Mirrlees company are to be found in 1840 when three Glasgow brothers, Peter, William and Andrew McOnie, set up a firm to manufacture cane sugar processing machinery. This under the title P. & W. McOnie. When J. B. Mirrlees became a partner on the resignation of William (later Sir William McOnie, Lord Provost of Glasgow) the firm became McOnie & Mirrlees.
As the partners either retired or died so the name of the company changed until in 1889 it had become Mirrlees, Watson & Yaryan Co. Ltd. And by 1898 the firm was again reconstructed as Mirrlees, Watson & Co., with Charles Day a manager. It was he who developed engine manufacturing. They supplied the first diesel engine to be installed in a naval ship. In 1908 Charles Day and H. N. Bickerton formed a new company solely for engine production, called Mirrlees, Bickerton & Day Ltd. A new factory was built at a small village called Hazel Grove, on the outskirts of Stockport in Lancashire.
After the Second World War Mirrlees became a member of the Associated British Oil Engines group of companies which Hawker Siddeley subsequently acquired in 1961. Mirrlees was merged with H. N. Bickerton’s old firm, National Gas & Oil Engine Co. Ltd. to form Mirrlees National Ltd. By comparison with Blackstone’s and Mirrlees, Hawker Siddeley was a mere newcomer to the world of engineering. Its roots were in the aircraft industry and was a product of a merger between Hawker Aircraft CO. and Armstrong Siddeley Ltd.
Hawker was founded in 1936 by the pioneer aviator T. O. M. ‘Tommy’ Sopwith and his chief designer Sidney Camm. The group is best remembered for its contribution to aviation history in two world wars: Sopwith Camel in the First and the Hawker Hurricane in the Second. Armstrong Siddeley grew out of the armaments, shipping and automobile engineering empire of William Armstrong based in Newcastle.
Until now Blackstone & Co. Ltd. had been controlled by a commercial board with responsibility for design and production taken by the Chief Engineer. In the management restructuring that followed the take-over the role of the Chief Engineer was redefined, his responsibilities being transferred to a Technical Director based at Hazel Grove. In theory this should have made Blackstone’s small and medium size engine technology available to a broader market. Which in the short term it did. Although the firm was able to develop their current range of engines to the limit of output they were unable to progress with the evolution of new designs.
The nineteen sixties was a good period for engine manufacturers. New markets were opening in the developing world and Blackstone’s were able to take advantage of them. However, increased production, particularly of the larger engines, and the imposition of more stringent test requirements showed up the inadequacies of the existing works, An extensive renewal programme, which would continue into the nineteen eighties, was put in hand. The Foundry, Heavy Machine Shop, Erecting and Testing Shops, and later, the Spares and Service Department, would all be re-equipped.
The programme began in 1966/7 when two Kearns horizontal borers were replaced with numerically controlled travelling column machines; one made by Schauman of Germany, the other by Kearns. The first of these was of considerable size with a horizontal traverse of eighteen feet and five feet vertically. It was used to bore cranks and for milling, drilling and tapping the end faces on EV in-line and twin bank engines. These operations had previously been carried out by three different machines and involved considerable movement from machine to machine. The Kearns was somewhat smaller with traverses of six feet horizontally and five vertically. This was used for facing the ends and drilling camshaft gear train bores of cylinder housings, also for boring and facing ends of marine and twin bank gearboxes. Control of both machines was by a British Ferranti system operated by pre-punched paper tape.
Other numerically controlled machines installed included a Jameson multi-spindle drilling machine with a thirteen feet table used primarily for drilling top faces of EV in-line and twin bank bases. Five holes could be drilled or tapped simultaneously. For drilling in-line and twin bank housings an Asquith horizontal drill with a twelve feet traverse was installed. A Heller horizontal mill with a planer head and a thirteen feet horizontal traverse was installed for machining cylinder housings and other components. A variety of components, such as exhaust, water and air manifolds, could be bored in one operation on a further Schaumann horizontal boring machine.
Nineteen sixty-nine saw the next stage of the reconstruction. A Webster and Bennet vertical boring mill was installed for turning flywheels and large gear blanks for marine and twin bank gear boxes. Meanwhile a new Test Shop, to replace three small sites, was built in which industrial, marine and dual-fuel engines up to 2,000 bhp could be tested. Engines were tested against water brakes, either direct-coupled or with straight or reverse/reduction gear boxes depending on their application.
Each test bed, complete with all necessary controls, was equipped with ring mains for all the required services, such as fuel oil and air, to which an engine on test could be coupled. A gas main fed by a compressor was provided for dual fuel engines. Engine lubrication oil, which passed through a continuous filtration plant before reuse, was supplied through a ring main with a capacity of 3,250 gallons. Cooling water was provided by a closed circuit system complete with aqua tower, pumping station and reservoir with a capacity of 150,000 gallons per hour. For each engine or alternator there was a bus bar installation connected to resistances at each end of every test bed capable of testing alternator sets up to 11,000 volts. Two electric cranes with capacities of 35 tons and 15 tons serviced the shop.
The Foundry was also modernised. First the original 250 feet long shop was extended by 300 feet. This made it possible to bring all operations under one roof. The extension doubled the foundry’s output to around 200 tons of finished castings a week. Castings weighing up to ten tons and up to 16 ft. 6 ins. long by 7ft. 6 ins. and 3 ft. 3in. wide became possible.
A motorised roller conveyor 130 feet long and 7ft. 3ins. wide was installed to carry patterns and pattern plates. The Pattern Shop was modernised to cope with the new foundry’s needs.
The production of castings at Blackstone’s was based on traditional techniques using dry sand moulds and oil sand cores. There was little mechanisation except for the handling of some of the moulding sand and in most cases by plain jolt-roll-over machines. Electric overhead cranes, most of which were over 50 years old, carried out all the handling of the mould, cores, pattern equipment, tables and castings. The core sand was loaded manually and hand rammed.
In 1965 a pattern flow system of mould production was introduced. Also the jolt-roll-over machines, which were at the end of their life, were replaced with sand slingers. In this year the first steps were taken in the development of the CO2 mould which laid the foundation for the future success of the foundry and was to make it the most modern in Europe. CO2 sodium silicate facing sand with green sand backing became the standard technique employed on all moulds, coupled with furane resin cold set cores. The CO2 process requires that the basic sand is new dry and cool. A self-contained sand drying and cooling plant and a new large sand mill was installed, along with bulk storage for sodium silicate and the CO2 supply.
With these improvements to the Moulding Shop attention turned to the Core Shop. Core manufacture had been a semi-mechanical process for time by using a sand slinger and box roll-over unit for the large cores and a core shooter for the medium cores. But the cores still had to be stoved and this caused a considerable bottleneck. The problem was solved by the introduction of the cold set furane resin process; the sand for this was produced in a mixer machine. The cold set furane resin process revolutionised the core shop in the same way that the CO2 process had in the moulding shop. All the old drying ovens were removed and, except for some small oil sand cores, which were dried in an oven, all cores were produced by the new method.
The Cupola Charging Plant was also modernised, as was the Fettling Shop. Here the addition of a spray paint booth enabled castings to be given a coat of red-oxide primer before being put into store. The restructuring of the works brought the advantages of increasing the size of casting and improving their quality and accuracy enabling them to be machined by the latest numerically controlled machine tools.
While all this modernisation was taking place other changes were afoot. In 1968 another attempt at a small vertical engine was made; the BV. This had a 7˝ in. bore and 7˝ in. stroke. Although a prototype was built it was shelved as the company, in the shape of the Technical Director, decided not to carry out any development.. This was a case of the Stamford Chief Engineer being over ruled by the Stockport. Unfortunately it led to some heated exchanges. The C.E. later said that Hawker’s were only interested in proven success and were not interested in spending money in developing potential success.
When Hawker Siddeley took over agricultural machinery implement production was moved from Stamford to Lister’s works at Cinderford in Somerset. This meant there was a need at Stamford for a second product. When the twin bank engine was introduced with its unique gearbox special gear-cutting machinery had been purchased. This machinery was under used, so to fill the product gap and to make use of otherwise idle machinery a Gear Division was formed. It was based out of Stamford at Easton on the Hill, about four miles west of the town, in Easton House. This is a grand building that in the 1820s had belonged to Henry Shuttleworth of Clayton and Shuttleworth & Co. Blackstone’s had purchased the house for use as a hostel for overseas visitors and foreign apprentices. Now it became, or part of it did, the design office of Ralph Ley, Blackstone’s Chief Engineer.
From here came some very successful gear and gearbox designs. In the 1970s, for example, 2,600 special gear and pinion sets were produced, to Ley’s design, for the London Passenger Transport Board when they re-equipped the Piccadilly underground line. The L.P.T.B. were having trouble with the alignment of the pinions for the motor-to-axle drive that overhung the motor shaft and caused a deflection, and thus wear, when load was applied. By redesigning the shape of the gear tooth Ley was able to bring the drive from the end to the centre reducing both deflection wear.
Once again the Stockport directors decided not to proceed with any further experimentation and closed the project.