Our editor has asked me to pen a few notes about my most recently completed project, a 5in. gauge Terrier. I completed my previous locomotive project, a Southern Railway L1 based on the LBSC Maid of Kent design, in November 2005, just in time for the Model Engineer exhibition, which in those days was held immediately after Christmas. Inevitably, as construction approached completion thoughts began to turn to a subject for the next project.
One of the problems experienced during the building of the L1 was the weight. As the locomotive approached completion handling became more and more difficult. Even the installation in the workshop of a runway beam and chain block only partially overcame the problem and it was decided that the next model would be of a smaller prototype.
I had always admired the diminutive little tank engines designed by William Stroudley when he became CME for the London Brighton and South Coast Railway. The decision to choose one of these engines as the prototype for the next project was finally clinched by my son commissioning Father Christmas to deliver a set of drawings for Martin Evans Boxhill design on 25th December 2005.
The L1 was commissioned successfully in January 2006 but the need for my own driving trolley was apparent and the design and construction of a suitable vehicle together with a number of other commitments delayed a start on the Terrier until July of that year.
When William Stroudley joined the London Brighton and South Coast Railway as CME in 1870 he found the existing locomotive stock totally inadequate for the demands of the rapidly expanding railway and was immediately faced with the need to design a new locomotive to satisfy many conflicting requirements. The small light weight 0-6-0 side tank engines which became known as Terriers were the result.
Anyone interested in the history of these remarkable little engines can do no better than read Tom Middlemass’s book Stroudley and his Terriers. Fifty of these locomotives were built and no less than ten have survived into preservation. They were not, of course, all built in one batch and inevitably changes and improvements were incorporated into the design as operational experience was gained. Some of these changes were incorporated from new, others introduced during rebuilds and by Stroudley’s successors.
Although Martin Evans chose to name his design Boxhill it incorporates a range of features which, whilst most appeared at some time during the development of the class, were not all present in the actual Boxhill. There were also features of the actual locomotive which do not appear in the Martin Evans version. Like many others who have built models based on this design, I felt that some attempt should be made to represent an actual prototype rather than produce a general representation of the class.
I, therefore, chose the last of the first batch of six engines to be out shopped from the LB&SCR Brighton Works, No. 70, Poplar. This locomotive is one of those that have survived into preservation and is still steaming today as Bodiam on the Kent and East Sussex Railway. Needless to say it has undergone a number of changes during the past 138 years. It was therefore decided to build the model to be as representative as possible of the locomotive in the condition it was originally out shopped in December 1872.
It is clear from the above comments that a number of changes to the Martin Evans design were necessary to achieve this objective together with the addition of significant detail not shown on his drawings. A number of additional modifications have been made to improve engineering detail, to facilitate assembly and to improve ease of operation on the track. For the benefit of anyone interested in following a similar course I will endeavour to describe the modifications which I introduced to the basic design and clarify some of the construction details left rather vague in Martin Evans drawings and articles.
The first and most glaring non-prototypical feature of the design to be changed was the drive for the mechanical lubricator. The drawings specify a return crank on the rear right hand crank pin driving a connecting rod to the lubricator mounted on the foot plate. No such feature existed on the prototype or at any stage during the development of the class. On the model of Poplar the lubricator is fitted immediately behind the front buffer beam and driven by a push rod which is ‘nudged’ by the end of the crosshead pump ram at the forward end of its stroke.
As can be seen from the picture, oil delivered by the lubricator is fed into the steam pipe rather than the steam chest as specified on the drawings. This improves atomization of the oil and distribution to the cylinders. The lubricator itself is a ratchet driven oscillating cylinder pump based on the time honoured LBSC design.
The braking system of the original Terriers was rather primitive and consisted of wooden brake blocks applied to the wheels through an uncompensated linkage by a mechanism which could be hand or steam powered. The steam operation proved to be unreliable and was soon replaced by a Westinghouse air brake system. The Westinghouse compressor on the right hand side of the cab became a distinctive feature of the engines.
The wooden brake blocks were also replaced by iron on the later engines. Martin Evans shows wooden blocks on his Boxhill drawings with only hand operation. The actual Boxhill was fitted with iron blocks and Westinghouse air brakes from new however, being one of the last three Terriers to be built and entering service in August 1880.
When originally out shopped Poplar was equipped with hand and steam powered wooden blocks and the brake pull rods were provided with a considerable amount of adjustment, presumably because the wooden blocks wore down fairly rapidly in service. It was almost ten years before the operation was upgraded to the Westinghouse system, but even then wooden blocks were retained initially.
No details of the original steam brake cylinders could be found. I, therefore, fitted my own interpretation of the device as shown, the hand operation mechanism being modified to suit. The adjustment facility built into the linkage of the prototype was also replicated.
One of the features of the design which I disliked was the installation of the boiler hand feed pump in the left hand side tank. This installation require a slot and removable section in the top of the tank to accommodate the pump operating lever and this is unsightly and non prototypical. I, therefore, installed the hand pump behind the rear buffer beam with access for the operating handle by lifting off the top of the dummy tool box.
