The firm of Marshall, Fleming & Jack established the Dellburn Works about 1890. The company specialised in cranes for steelworks, and these established its reputation for high quality engineering.
This crane is one of a batch made for the LMS Civil Engineer's Department between 1927 and 1930. As supplied, the jibs of these cranes were the usual swan-neck type but they were soon altered to straight section, as shown by this example. It has a 3-axle carriage, and each axle is sprung to assist travelling in a train to and from the work site. In addition, when working, a permanent way crane must be able to travel while supporting its full rated load. Hence blocking girders are seldom used, but as weight is transferred to the wheels under the jib during lifting it is necessary to chock the springs to prevent undue sinking. This in itself creates uneven wheel loading when travelling with a load on uneven track, and the crane carriage must be massively constructed to transfer the forces created.
The crane is numbered in the LMS 1941 scheme, which allocated letters as follows:-
MP - breakdown cranes, the letters referring to the responsible department "Motive Power";
RM - Railway cranes Manual;
RS - Railway cranes Steam (i.e. able to lift, derrick, slew and travel under power);
PM - Portable cranes Manual;
PM - Portable Cranes Steam (i.e. yard cranes with no powered travel).
See J.S.Brownlie, Railway Steam Cranes; A Survey of Progress since 1875, Glasgow 1973.
The runner wagon in this picture is British Railways 22 ton steel sided Plate Wagon No.DB932307.