Dr Alex Moulton
1988. Alex Moulton on the terrace at The Hall.
having accepted a position within the family firm. Even at this early stage, he had discovered the design potential offered by methods of permanently bonding rubber to metal and was keen to develop shear and torsion springs using this new process. As the technical staff of Spencer Moulton returned to London (having relocated to Bradford during hostilities), Alex began his experiments. Before long, frustrated by his incomplete engineering knowledge and with the blessing of his bosses, he went back to Cambridge to finish his degree. As is so often seen nowadays, his experience at Bristol increased his desire to learn and his ability to put theory into practice.
Perhaps influenced by the unforgiving nature of aeronautical engineering, Moulton’s thread of needing to achieve a deep understanding of fundamentals before tackling a problem was to run throughout his career. Whilst the properties of rubber in compression and the simple springs constructed in this way were well understood, loading cases such as shear and bending were relatively untested. Moulton was intrigued by the ‘Torsilastic’ tubular rubber bush pioneered by Alvin Krotz and, using this as proof of concept, developed his own – somewhat simpler to attach to a chassis – version, later known as ‘Flexitor’ suspension and in widespread use on road trailers, the Bond Minicar and the Austin Gypsy,
At this stage, striving to establish some laws of behaviour for these new rubber springs, Moulton recruited Philip Turner from Cambridge University. Turner, a brilliant physicist, made mathematical sense of the
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Late 1962, with pre-production Moulton bicycle and Austin 1100 with Hydrolastic suspension.
fatigue and creep tests that Spencer Moulton was undertaking and made a great contribution to the reliability and durability of rubber suspension systems that, in later years, would appear on millions of British cars. Moulton and Turner published a paper in 1950 – Influence of Design on Rubber Springs and this was followed a year later by Development and Testing of a Series of Rubber Suspension Units. Despite Spencer Moulton’s strong links with the rail industry, Moulton was keen to exploit his inventions in the rapidly-burgeoning automotive sector. By good fortune, he had recently formed a strong friendship with a project engineer at Morris Motors by the name of Alec Issigonis.
Issigonis, a suspension expert himself, had shot to fame in 1948 with the instant success of the Morris Minor. He was, however, disparaging of Moulton’s work. “Rubber”, he stated, “is not an engineering material”. It was not until 1953, after Issigonis had left Morris to join Alvis, that Moulton was able to equip a Minor with rubber suspension. Tested at MIRA, with a modified seismograph on the rear seat to measure vertical acceleration, this car was the first ever to cover 1000 miles on the pave without fault. Issigonis was suitably impressed and brought Moulton into his team at Alvis. Rubber cone springs – developed initially as engine mounts – working in compression and shear were used in series ‘nose-to-nose’ on struts for the vehicle suspension. The ride was satisfactory but Moulton and Issigonis, having toyed with the idea of hydraulic interconnection for years, realised that if the springs were placed ‘back- to-back’ they could be used as fluid-displacers
as well as primary springs. Moulton was later to recall “the revelation at Coventry, with Alec driving, of experiencing the ‘big car’ ride due to the lowered pitch frequency. The reality of the benefit of fluid interconnection was thus revealed and the seed was sown, not that we realised it then, for a radical new suspension to be made in vast numbers”.
1955 saw a great deal of change. Spencer Moulton was absorbed in the Avon Rubber Company. Issigonis moved back to BMC and persuaded them to sign up Moulton as a suspension consultant on an exclusive basis. Moulton himself, completely convinced by the benefits of interconnection, turned the stable block at his family home into a development and testing workshop and worked night and day to analyse the characteristics, obtain quantifiable data and derive formulae to predict behaviour of the new suspension systems. Looking at his sketches from this creative period, there are many fascinating concepts that defied any analysis other than the reality of making and testing – very much the Moulton design ethos – and his team in the workshop were not short of work. Moulton would later comment that “we had no analogy to fall back on; indeed the devices were more akin to biological organs than engineering mechanisms”. As the Hydrolastic concept reached the convergence stage – a levered, short-stroke unit with a reinforced diaphragm pushing the hydraulic fluid through a damping valve, with a rubber ‘cheese’ in shear and compression as a bounce spring – stroking rigs tested each design iteration for fatigue problems. Moulton used this ‘design-make-
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