James Thompson Marshall
James Thompson Marshall (1855-1931) of Marshall, Sons and Co was a British railway and mechanical engineer known for inventing the 'Marshall valve gear' for steam locomotive use.
1854 Born in Wragby, Lincolnshire[1]
James Marshall began his engineering career at the Steam Plough Works
J. T. Marshall invented and patented several different valve gears but these should not be confused with the "Marshall valve gear" patented by Marshall, Sons and Co. in 1879. At least one of J. T. Marshall's valve gears was a rotary type and the only known application was to the Austrian BBÖ Class 114 locomotive.
1881 Mechanical engineer and machine maker, 26, living in Gainsborough with Mary J. Marshall 27, Arthur Marshall 5, Ada F. Marshall 4[2]
Later moved to the Boyne Engine Works, Leeds.
1901 James T Marshall 46, mechanical engineer, living in Leeds with Mary Marshall 48, Gertrude Marshall 19, Alice Marshall 16[3]
The better-known J. T. Marshall gear was a modified Walschaerts valve gear which was first applied to a Great Northern Railway mineral locomotive, no. 743, in 1901 and received a glowing report. Next, it was tried on GNR Class C2 No. 1520 in March 1903. There was no external change visible on the locomotive as a result of this modification. When the valve gear was in use, the motion was derived from two eccentrics, one of which gave lap and lead movement by swinging the link backwards and forwards on its suspension bracket. The other eccentric was set at 90 degrees to the crank and rocked the link by means of a bell crank on the hanging link pin. The position of the radius rod die pin in the link determined the direction of movement and the cutoff. Showing little advantage over the normal Stephenson link valve gear, it was removed from the C2 'Atlantic' in April 1907 to ease maintenance.
A modified version of the gear (for outside drive) was tried on SECR N class no. 1850 in 1933-4 but, again, it was not a great success.
1931 Obituary[4]
"THE LATE MR. J. T. MARSHALL.
Many of our readers will hear with regret of the death of Mr. James Thompson Marshall, which occurred at Harrogate on December 5, at the age of 76.
Mr. Marshall, who was born in 1855, was a member of the well-known family of Gainsborough engineers, and served his apprenticeship with the firm which is now entitled Marshall, Sons and Company, Limited. During this time and subsequently, when tor a period he held an appointment on the staff, he gained valuable experience in the design and manufacture of steam engines of various types and was fond of recalling that on one occasion it had been his lot to work continuously for four days and nights on the steam-driven haulage gear, which was urgently required for recovering the broken Atlantic telegraph cable. At the age of thirty he joined the firm of Messrs. John Fowler and Company, of Leeds and, while a member of their technical staff, invented and patented a number of valve gears, balanced slide valves and automatic governors, for both locomotive and stationary engines. It was, in fact, in this direction, rather than on the commercial side, that his bent lay, and on his retirement some twenty years ago it is not, therefore, surprising to find him devoting himself more particularly to the problem of overcoming the high compression, which is common in locomotive cylinders at high speeds when ordinary valve gears are employed.
His studies in this direction resulted in the invention of a gear which in essentials comprised a main steam valve, with an expansion valve on the back of it, and independent exhaust valves, all of which were actuated by gears with separate expansion and reversing links of the slotted type. In this equipment the point of admission was regulated by the main steam valve, which had a constant travel, so that the amount of lead was also constant. The cut-off was regulated by the expansion valve, which could be controlled either automatically or by hand. The points of release and compression were determined by the exhaust valves. These valves were worked by the gear which actuated the main steam valve and the points were thus not affected by any degree of linking up of the expansion valve. Cylinder clearance space was reduced to a very small amount by the shortness of both the steam and exhaust ports and the shallowness of the valves. As is well known with the ordinary Stephenson gear linking-up may result in serious wire-drawing with the result that a considerable loop, showing negative work, appears on the card. Mr. Marshall claimed that the use of his gear would enable this attenuated diagram to be filled out and a material increase in power achieved.
This gear received a wide application on stationary engines, but its use on locomotives, where its inventor hoped it would find its greatest utility, was not so marked. Nevertheless, it was being tried out by one of the leading railway companies and. it is, perhaps, unfortunate that ill-health, following on a surgical operation to which he had to submit in 1928, prevented him from pressing its claims to the full. Mr. Marshall was, throughout his life, a sturdy champion of steam power, but clearly saw that its development was in many directions retarded by the uneconomical operating conditions. His efforts were therefore rightly directed to bringing about a much needed change in this respect, and for this his work is deserving of recognition."
See Also
Sources of Information
- ↑ BMD
- ↑ 1881 census
- ↑ 1901 census
- ↑ Engineering 1931/12/18