Please be aware of our copyright notice. If you have a good reaon for using a photo from this site ask permission from first - it is frequently given.
![]() photograph: Mike Morant collection
|
The Z class was the only Maunsell eight-coupled design
to materialise, although there were plans for others. It was designed and
produced for the specialist role of heavy shunting in hump and marshalling
yards. In doing so a considerable number of standard parts and an existing
Brighton boiler design were utilised, this class also incorporating the
experience of the Urie G16 class 4-8-0T which had
been produced for the same purpose. The specialist requirements were for a
locomotive which was capable of delivering a lot of power after lengthy periods
of idling, to do so without excessive blowing off and slipping, being quiet in
operation and to be able to negotiate tight curves.
To achieve the required specification a large water and steam capacity was required, the boiler selected was of the parallel non-superheated type with a moderate grate area of 18.6 sq ft and total evaporative heating surface of up to 1279 sq ft. The boiler pressure was 180 lb per sq in resulting in a tractive effort at 85 percent pressure of 29,380 lb. The water tanks could hold 1500 gallons and the coal bunker 3 tons. Three 16in diameter 28in stroke cylinders (interchangeable with those on N1 and U1 classes) were used, the outside pair driving the third axle through 11ft 6in connecting rods and the inside cylinder set at 1 in 8 driving the second axle. Walschaerts valve gear controlled the outside pistons, the inside one having custom designed gear. The wheels were of 4ft 8in diameter and the leading and trailing pair had sufficient sideplay so that curves of 4½ chains could be negotiated despite the 17ft 6 in wheelbase. The only adverse feature was the overhang of 11ft at each end which meant that the class could only be used where sharp curves were not in tight surroundings. Steam brakes were fitted as was vacuum apparatus and a steam reverser. Steam heating for passenger stock and banana vans was also provided. The overall result was a responsive, powerful engine practically immune to slipping with a very quiet beat. Eight locomotives numbered 950-957 (30950-7 under BR) were built at Brighton works in 1929. Such was the success of the class that a further ten were planned for Eastleigh works in 1931 but were cancelled because of the economic climate. Instead with much farsightedness ultimately three diesel electric shunters were ordered. This class quietly and without ceremony went about its designed tasks successfully for its entire life, although they were not as successful at trip workings as the G16s. Three, 951/5/6, were loaned to the war department during World War Two and served in Scotland. Throughout their lives they were allocated to Ashford, Brighton, Dover, Eastleigh, Exmouth Junction, Gillingham, Hither Green, Salisbury, Templecombe, Three Bridges and Tonbridge. Towards the end of their lives they took their turn on banking duties up the 1 in 37 hill from Exeter St Davids to Exeter Central. Their appearance was largely unchanged throughout and the entire class was withdrawn throughout 1962. Regrettably none is preserved. |
|
Introduced: Driving Wheel: Length: Total Weight: Water Capacity: Cylinders (3): Boiler Pressure: Tractive Effort: Coal Capacity: Power Classification: |
Mar 1929 4 ft 8 ins 39 ft 4 in 71 tons 12 cwt 1,500 gals 16 in x 18 in 180 lb sq in 29,376 lb 3 ton 0 cwt 6-F |
SR N° | BR N° | Built | Withdrawn |
950 | 30950 | Apr 1929 | Nov 1962 |
951 | 30951 | May 1929 | Nov 1962 |
952 | 30952 | May 1929 | Nov 1962 |
953 | 30953 | Jun 1929 | Dec 1962 |
954 | 30954 | Sep 1929 | Dec 1962 |
955 | 30955 | Jul 1929 | Dec 1962 |
956 | 30956 | Mar 1929 | Dec 1962 |
957 | 30957 | Aug 1929 | Nov 1962 |
This page was last updated 7 August 2011