With a production run of 478 Class 24 & 25's it is not surprising to find that there are a number of variations featured on the locomotives. These differences resulted from changing conditions on BR, for example the discontinuance of train identification by lamps & discs, replaced by four digit alpha/numeric headcodes, and the correction of errors found in the early designs, in the case of the BR Type 2's it would be the repositioning of the air filters from the body sides to the cantrail area.
Close examination of the Class 25 cab roofs indicate there are distinctive differences with regard to the height of the horn moulding and the length of the sloping flat panel coming down from the top of the headcode box and as it ends how it interacts with the curves of the cab roof moulding.
Class 25/2 & 25/3 Three views above showing the revised cab roof moulding carried on the Class 25/2 and Class 25/3's with certain exceptions. The top of the horn moulding is now flush with the sloping flat panel (there is no shadow line). The sloping flat panel does not extend as far down the roof as in the Class 25/1 variant causing less of a curve in the line created by the change of direction from the side of the headcode box out to the the point where the sloping panel joins the curved roof.
Class 25/2 with Class 25/1 cab roof style Although 25218 - 25247 (7568 - 7597) were designated Class 25/2's they carried the cab roof style from the Class 25/1's - see information above. Again there are inconsistancies in this group, close scrutiny of the locomotives coming out of Darlington D7578 - D7597 (25228 - 25247) reveal that both types of the later mouldings were used.
25271 in the process of scrapping at Derby Works, at some point the cab caught fire, exposing the steelwork that was used to support the cab roof moulding. Also at Derby Works is 25295 which appears to be displaying a very thin shadow line between the top of the horn moulding and the sloping flat panel. And finally five cabs at Derby Works awaiting.............
The above views clearly indicate a distinct cab roof variant between the Class 25/1 and early Class 25/2 builds when compared with the later Class 25/2 and 25/3 builds. Presumably moulds were used to form the cab roofs, very minor differences in these moulds could explain the very thin shadow line on 25295 above, or is it a trick of the light?
Cab Roof Variants.
This same batch of locomotives can also be found fitted with the cab roof styles carried by 5176 (25026) onwards. Presumably when this occurred the air horns remained at their buffer beam location. Locomotives that carried the later roofs include 24134, 24142, 25006, 25008, 25010, 25015.
Cab Roof/Headcode Oddities.
Boiler Room Grille Variants.
The harsh Highland winters led to the original boiler room grill being covered with a solid blanking plate with either four or five slats to allow a reduced airflow.
Five slat blanking plate: 5114, 24115, 24116, 24117, 24118, 24119, 24121, 5122, 24125, 24126, 24130, 24132
Four slat blanking plate: 24127
Solid blanking plate: 24120, 24124, 24128, 24129
Original style grill: 24123
Glasgow Works modified the roof level water filler access by sheeting it over. This method of filling had become redundant following the dismantling of the platform end water fillers used by the steam locomotives. It would also be one less maintenance headache for the locomotives operating in the harsh Highland winters. Picture evidence suggests this modification began about 1967/1968.
Cantrail water level filler sheeted over: 5114, 24115, 24116, 24117, 24118, 24119, 24120, 24121, 5122, 24123, 24124, 24125, 24126, 24128, 24129 :
Not sheeted over: 24127 & 24130 (as of scrapping?), 24132 (as of Aug 1972)
Boiler Room Grille (Class 25).
With the end of the Class 24 build the production lines at Derby & Darlington moved on to the production of the Class 25's. As they came off the production line there were no external changes to the boiler room grills throughout the entire run of the Class 25s, despite the fact that boilers were not fitted to many of these locomotives!
Over time, and similar to many of the Class 24's, a solid blanking plate was fitted over the grills to minimise the intake of dust and water into the locomotive. At a date unknown Derby Works began removing the grills and sheeting over the opening as the locomotives came through the Works. In some cases the entire panel from the frame level to the roof line was replaced. It is not known when this practice stopped and it appears that it was only carried out at Derby Works.
Three examples of the modification are shown below.
In the above views it appears that 25161 & 25214 have had the whole panel replaced, whilst 25177 has only had the aperture skinned over, the location of the former grill is clearly visible.
Class 25's known to have had the boiler room grill sheeted over - date in brackets indicates modification date (list may be incomplete):
25100, 25101, 25102, 25104, 25105, 25107
The fuel and water tanks carried by the Class 24's, at first glance appeared to be all the same, in fact they are not. Because these locomotives were over their designed weight when built various changes were made to reduce the weight. These changes included reducing the fuel and water tank capacity, consequently minor design changes took place as the locomotives were built.
All the views immediately below unless otherwise indicated feature the locomotive photographed with the radiator end nearest the camera, the nearest tank to the camera will be the fuel tank.
D5000 - D5049 (24001 - 24049)
The first fifty Class 24's (thirty from Derby & twenty from Crewe) carried the first version of the fuel/water tanks. As can be seen from the views below these, with the batteries gave a solid appearance to the underframe area between the bogies. But because of the locomotives being over their design weight it was necessary to resort to weight saving schemes for the later build, and to take steps for weight saving refinements retroactively for these first fifty machines.
Retro-actively for D5000 - D5049 it was the water tank that was altered by shortening the tank at the end nearest the centerline of the locomotive (see view below of 5025). Not all of the locomotives were retrofitted, at least 24012/16/38/41/42/44/45 carried the full size tanks to the end.
Some tanks gained a circular gauge class usually only on the fuel tank, locomotives so fitted include 5028, 24006/25/34/38/, exceptions include 24046/49 which had the circular gauges on both fuel and water tanks!
Locomotives which had their water tanks removed in this group are 24032/34/35/39.
Weight saving measures regarding the fuel tanks went into production beginning with D5050 - where the tank wrapped round the battery box it no longer reached upto the frame level, the modified designed created a shallower end section. This production change affected all the locomotives up to D5120 which included those produced by Crewe, Darlington & Derby.
This batch of locomotives included the Gateshead allocated machines which were later designated for the Tyne Dock - Consett iron ore services - for this their steam heating boilers and water tanks were removed permanently.
Over time some members of this group received the lighter water tank, this was shortened and created a gap between the fuel & water tanks under the battery boxes. Locomotives receiving the lighter tank included 24054/73/76-84/86/87/89/90/92, 24113/118/119.
Other machines saw the circular gauges added to the tanks:
Some machines late in their careers had the water tank removed these include 24063/81/86/91.
In the middle of the Derby build for the Scottish Region the design of the water tank was changed. To reduce its size the length was reduced creating a gap between it and the fuel tank beneath the battery boxes. For the Class 24's, after this third production change there were no others. All changes after this point for the Class 24's were done retro-actively.
Many of this group would later be fitted with circular gauges for both the fuel & water tanks, particularly true for the Scottish examples. Those so treated were 24121/123/124/125/128/129/137/146/148.
Several locomotives only had the circular gauge added to the fuel tank, these included 24126/127/130/132/141. Also in this group were a number of locomotives that had the water tank removed, included in this group is 24134.
The battery isolating switch was situated behind a hinged two piece cover midway along the side of the locomotive, close to the handholds that provided access to the cantrail level water filler. The cover remained unchanged throughout the build of the Class 24/25's. In service the lower part of the cover would often appear in the open position, revealing the isolating switch.
Modifications to the access cover to the battery isolating switch were not that common, these changes appear to be mostly the work of the Scottish Region.
Class 25's with this modification include 7578 (25228), 25005, 25037 & 25087.
24129 has the modification but is hinged on the opposite side to the above locomotives.
Each locomotive carried builders plates, initially fitted to the cabside but later many were moved to the cab door. In later years many locomotives ran without the plates.
Although only a small item there were variations within the styling of the builders plate.
For the Class 25's the plate styles were similar in 1963, 1964 and early 1965, but later in 1965 the 'D' in 'associated' was no longer capitalised.
Temporary Modifications & Experiments.
From time to time locomotives were temporarily modified in order to test a variety of experiments. Many of these experiments were not of a visible nature apart from a small modification plate usually located somewhere near the cab door.
7500 (25150) carried a cab ventilation modification - a ventilation opening the width of the cab door and about 8 inches tall was located above the door in the roof panel, whilst there was a 6.5 inch square aperture cut into the lower part of the cab door. It is not known how long the locomotive ran with this modification.
Page added June 6th 2001