Basic Details
Class 24 & 25

Particulars for both Class 24 & 25

Wheel arrangement: Bo-Bo
Length over buffers: 50ft 6in
Height over cowl: 12ft 8in
Width: Class 24 - 9ft 1.375in; Class 25 - 8ft 1.625in
Total Wheelbase: 36ft 6in
Bogie Wheelbase: 8ft 6in
Bogie Pivot Centres: 28ft 0in
Minimum curvature: 4.5chains (297ft) radius
Length over buffers: 50ft 6in
Wheel Diameter: 45in

Class 24

Total Built: 151
Builders: British Railways Workshops: Derby, Crewe & Darlington
Delivered: August 1958 - February 1961
Service Life: August 1958 - October 1980
Traction Motor Gear Ratio: 81 : 16
Engine Continuous Rating: 1,160hp at 750rpm
Power absorbed by auxiliaries (average): 65bhp
Maximum Tractive Effort at rail: 40,000lbs (24.2% adhesion)
Maximum Current: 2,340amps
Continuous Tractive Effort at rail: 21,300lbs at 16.5 mph
Continuous Generator rating: 720kW, 525 volts, 1,400 amps; 750 volts 980 amps
Maximum Speed: 75 mph
Fuel Tank Capacity D5000 - D5049: 630 gallons
Fuel Tank Capacity D5050 - D5150: 520 gallons
Auxiliary Fuel Tank Capacity D5000 - D5049: 20 gallons
Auxiliary Fuel Tank Capacity D5050 - D5150: 10 gallons
Boiler Water Capacity D5000 - D5049: 600 gallons
Boiler Water Capacity D5050 - D5150: 520 gallons
Cooling Water Pressure (engine running): 15 lb/sq in
Water Temperature: max 185F, normal 165F - 175F
Lubricating Oil Capacity: 100 gallons
Lubricating Oil Temperature: max 185F, normal 160F - 170F
Engine Oil Pressure (full power): 50 lb/sq in
Charging Air Pressure (full power): 9-12 lb/sq in
Exhaust Temperature: All cylinders to be within 100F of each other
Engine: Sulzer 6LDA28A pressure-charged four stroke
Main Generator: AEI Type RTB 15656
Traction Motors: 4 x AEI Type 137BY or BX
Steam Generator D5000 - D5003: Type OK4616A
Steam Generator D5004 - D5043: Type OK4616B
Steam Generator D5044 - D5150: Type L4610

Class 25

Total Built: 327
Builders: British Railways Workshops: Derby, Darlington; and Beyer Peacock Ltd, Manchester
Delivered: April 1961 - May 1967
Service Life: April 1961 - March 1987
Traction Motor Gear Ratio 25001 - 25025: 79 : 18
Traction Motor Gear Ratio 25026 - 25327: 67 : 18
Engine Continuous Rating: 1,250hp at 750rpm
Power absorbed by auxiliaries (average): 65bhp
Maximum Tractive Effort at rail 25001 - 25025: 39,000lbs
Maximum Tractive Effort at rail 25026 - 25327: 46,500lbs
Maximum Current 25001 - 25025: 2,525amps
Maximum Current 25026 - 25327: 2,640amps
Continuous Tractive Effort at rail: 20,500lbs at 18 mph
Continuous Generator rating 25001 - 25025: 817kW, 750 volts, 1,090 amps; 545 volts 1,500 amps
Continuous Generator rating 25026 - 25327: 780 volts, 1,050 amps; 545 volts 1,500 amps
Maximum Speed: 90 mph
Fuel Capacity : 510 gallons
Boiler Water Capacity 25026 - 25028, 25033 - 25087, 25218 - 25247: 580 gallons
Lubricating Oil Capacity: 100 gallons, maximum on dipstick indicates 86 gallons
Coolant Capacity: 186 gallons
Water Temperature: max 185F, normal 165F - 175F
Engine: Sulzer 6LDA28B pressure-charged four stroke
Main Generator: AEI Type RTB 15656
Auxiliary Generator: AEI Type RTB 7440
Traction Motors 25001 - 25025: 4 x AEI Type 137BY or BX
Traction Motors 25026 - 25327: 4 x AEI Type 253AY
Traction Motor Rating 25026 - 25327: 650 amps at 315 volts
Traction Motor Gear Ratio: 67 : 18
Steam Generator 25026 - 25028, 25033 - 25087, 25218 - 25247: Stone Vapor L4610
Weight in Working Order 25026 - 25028, 25033 - 25082, 25218 - 25247: 73 tons 15cwt
Weight in Working Order 25029 - 25032: 71 tons 9cwt
Weight in Working Order 25083 - 25087: 73 tons 1cwt
Weight in Working Order 25088 - 25217, 25248 - 25327: 70 tons 14cwt
Maximum Axle Loads 25026 - 25028, 25033 - 25082, 25218 - 25247: 18 tons 17cwt
Maximum Axle Loads 25029 - 25032: 18 tons 5cwt
Maximum Axle Loads 25083 - 25087: 18 tons 12cwt
Maximum Axle Loads 25088 - 25217, 25248 - 25327: 18 tons 1cwt

Sources:
Operating Manual British Railways Locomotives D5000 - D5175; dated January 1962
Operating Manual British Railways Locomotives D5176 - D5299, D7500 - D7677; dated July 1966

Page added May 16th 2011

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