Sub class:	25/0	25/1	25/2	25/3	25/9
TOPS number range:	25001 25025	25026 25082	25083 25247	25248 25327	25901 25912
1957 BR number range:	D5151-D5175	D5176-D5232	D5233-D7597	D7598-D7677	Renumbered from 25/3
Former class codes:	D12/1, later 12/1	D12/1, later 12/1	D12/1, later 12/1	D12/1, later 12/1 D7598-D7619 classified 12/1A	-
Built by:	BR Darlington	BR Darlington, BR Derby	BR Darlington, BR Derby	BR Derby, Beyer Peacock	N/A
Introduced:	1961-62	1963	1963-66	1965-67	1986
Wheel arrangement:	Bo-Bo	Bo-Bo	Bo-Bo	Bo-Bo	Bo-Bo
Weight (operational):	72 tonnes	72 tonnes	76 tonnes	76 tonnes	76 tonnes
Height:	12ft 8in	12ft 8in	12ft 8in	12ft 8in	12ft 8in
Width:	9ft 1 in	9ft 1 in	9ft 1 in	9ft 1 in	9ft 1 in
Length:	50ft 6in	50ft 6in	50ft 6in	50ft 6in	50ft 6in
Min curve negotiable:	4 Chains	4 Chains	4 Chains	4 Chains	4 Chains
Maximum speed:	90 mph	90 mph	90 mph	90 mph	60 mph
Wheelbase:	36ft 6in	36ft 6in	36ft 6in	36ft 6in	36ft 6in
Bogie wheelbase:	8ft 6in	8ft 6in	8ft 6in	8ft 6in	8ft 6in
Bogie pivot centres:	28ft	28ft	28ft	28ft	28ft
Wheel diameter:	3ft 9in	3ft 9in	3ft 9in	3ft 9in	3ft 9in
Brake type:	Vacuum	Vacuum, later Dual	Vacuum, later Dual	Vacuum, later Dual	Dual
Sanding equipment:	Pneumatic	Pneumatic	Pneumatic	Pneumatic	Pneumatic
Heating type:	Steam - Stones vapor 4610,	Steam - Stones Vapor 4610,	Steam - Stones vapor 4610 fitted to D7568-D7597	Not fitted	Not fitted
Route availability:	5	5	5	5	5
Coupling restriction:	Blue Star	Blue Star	Blue Star	Blue Star	Blue Star
Brake force:	38 tonnes	38 tonnes	38 tonnes	38 tonnes	38 tonnes
Engine type:	Sulzer 6LDA28B	Sulzer 6LDA28B	Sulzer 6LDA28B	Sulzer 6LDA28B	Sulzer 6LDA28B
Engine horsepower:	1,250hp	1,250hp	1,250hp	1,250hp	1,250hp
Power at rail:	949hp	949hp	949hp	949hp	949hp
Tractive effort:	45,0001b	45,0001b	45,0001b	45,0001b	45,0001b
Cylinder bore:	11 in	11 in	11 in	11 in	11 in
Cylinder stroke:	14 in	14 in	14 in	14 in	14 in
Main generator type:	AEI RTB 15656	AEI RTB 15656	AEI RTB 15656	AEI RTB 15656	AEI RTB 15656
Aux generator type:	AEI RTB 7440	AEI RTB 7440	AEI RTB 7440	AEI RTB 7440	AEI RTB 7440
Number of traction motors:	4	4	4	4	4
Traction motor type:	AEI 137BX	AEI 253AY	AEI 253AY	AEI 253AY	AEI 253AY
Gear ratio:	67:18	67:18	67:18	67:18	67:18
Fuel tank capacity:	500gal	500gal	500gal	500gal	500gal
Cooling water capacity:	187gal	187gal	187gal	187gal	187gal
Boiler water capacity:	580gal	580gal	580gal	Not fitted	Not fitted
Lub oil capacity:	100gal	100gal	100gal	100gal	100gal
Boiler fuel capacity:	From main supply	From main supply	From main supply	Not fitted	Not fitted