The 3521 Class were forty tank locomotives designed by William Dean to haul passenger trains on the Great Western Railway

Great Western Railway

The Great Western Railway was a British railway company that linked London with the south-west and west of England and most of Wales. It was founded in 1833, received its enabling Act of Parliament in 1835 and ran its first trains in 1838...

. They were introduced as 0-4-2T locomotives in 1887, but were quickly altered to become 0-4-4Ts to improve their running. Following two serious accidents they were further altered from 1899 to run as 4-4-0

4-4-0

Under the Whyte notation for the classification of steam locomotives, 4-4-0 represents the wheel arrangement of four leading wheels on two axles , four powered and coupled driving wheels on two axles, and no trailing wheels...

 tender locomotives, in which form the last was withdrawn in 1934.

0-4-2T standard gauge

The first twenty locomotives were turned out in 1887 as 0-4-2T locomotives for services on the standard gauge

Standard gauge

The standard gauge is a widely-used track gauge . Approximately 60% of the world's existing railway lines are built to this gauge...

 lines.

• 3521
• 3522
• 3523
• 3524
• 3525
• 3526
• 3527
• 3528
• 3529
• 3530

• 3531
• 3532
• 3533
• 3534
• 3535
• 3536
• 3537
• 3538
• 3539
• 3540

0-4-2T broad gauge

In 1888 a further batch of twenty were ordered as 0-4-2

0-4-2

Under the Whyte notation for the classification of steam locomotives, 0-4-2 represents the wheel arrangement with no leading wheels, four powered and coupled driving wheels on two axles, and two trailing wheels on one axle...

ST saddle tanks for the broad gauge

Broad gauge

Broad-gauge railways use a track gauge greater than the standard gauge of .- List :For list see: List of broad gauges, by gauge and country- History :...

 lines in Devon

Devon

Devon is a large county in southwestern England. The county is sometimes referred to as Devonshire, although the term is rarely used inside the county itself as the county has never been officially "shired", it often indicates a traditional or historical context.The county shares borders with...

 and Cornwall

Cornwall

Cornwall is a unitary authority and ceremonial county of England, within the United Kingdom. It is bordered to the north and west by the Celtic Sea, to the south by the English Channel, and to the east by the county of Devon, over the River Tamar. Cornwall has a population of , and covers an area of...

.

• 3541 (1888 - 1890)
• 3542 (1888 - 1891)
• 3543 (1888 - 1891)
• 3544 (1888 - 1890)
• 3545 (1888 - 1891)
• 3546 (1888 - 1890)
• 3547 (1888 - 1891)
• 3548 (1888 - 1891)
• 3549 (1888 - 1891)
• 3550 (1888 - 1890)
• 3551 (1888 - 1890)
• 3552 (1888 - 1890)
• 3553 (1888 - 1890)
• 3554 (1889 - 1891)
• 3555 (1889 - 1890)
• 3556 (1889 - 1890)
• 3557 (1889 - 1891)
• 3558 (1889 - 1890)
• 3559 (1889 - 1890)

0-4-4T broad gauge

Due to the unsteady running of the 0-4-2STs, the last of the order, 3660, was turned out in August 1889 as a 0-4-4

0-4-4

Under the Whyte notation for the classification of steam locomotives, 0-4-4 represents the wheel arrangement of no leading wheels, four powered and coupled driving wheels on two axles, and four trailing wheels on two axles...

T bogie side tank. The remainder of the class were altered to a similar layout over the following two years. 3660 was slightly different at this time, having a bogie that was six inches shorter and an overall wheelbase of 20 ft 8 in, rather than the 21 ft 4 in of the converted locomotives.

• 3541 (1890 - 1892)
• 3542 (1891 - 1892)
• 3544 (1890 - 1892)
• 3545 (1891 - 1892)
• 3546 (1890 - 1892)
• 3548 (1891 - 1892)
• 3549 (1891 - 1892)
• 3550 (1890 - 1892)
• 3551 (1890 - 1892)
• 3552 (1890 - 1892)
• 3553 (1890 - 1892)
• 3554 (1891 - 1892)
• 3555 (1890 - 1892)
• 3556 (1890 - 1892)
• 3557 (1891 - 1892)
• 3558 (1890 - 1892)
• 3559 (1890 - 1892)
• 3660 (1889 - 1892)

0-4-4T standard gauge

The standard gauge

Standard gauge

The standard gauge is a widely-used track gauge . Approximately 60% of the world's existing railway lines are built to this gauge...

 0-4-2Ts were converted to 0-4-4Ts in the same manner as the broad gauge

Broad gauge

Broad-gauge railways use a track gauge greater than the standard gauge of .- List :For list see: List of broad gauges, by gauge and country- History :...

 locomotives, which were all eventually converted to standard gauge. By the end of 1892 the whole class of forty locomotives was to one standard design for the first time.

• 3521
• 3522
• 3523
• 3524
• 3525
• 3526
• 3527
• 3528
• 3529
• 3530
• 3531
• 3532
• 3533
• 3534
• 3535
• 3536
• 3537
• 3538
• 3539
• 3540
• 3541 (1892 - )
• 3542 (1892 - )
• 3543 (1891 - )
• 3544 (1892 - )
• 3545 (1892 - )
• 3546 (1892 - )
• 3547 (1891 - )
• 3548 (1892 - )
• 3549 (1892 - )
• 3550 (1892 - )
• 3551 (1892 - )
• 3552 (1892 - )
• 3553 (1892 - )
• 3554 (1892 - )
• 3555 (1892 - )
• 3556 (1892 - )
• 3557 (1892 - )
• 3558 (1892 - )
• 3559 (1892 - )
• 3660 (1892 - 1899)

On 13 April 1895 3521 and 3546 derailed near Bodmin Road

Bodmin Parkway railway station

Bodmin Parkway railway station is a station on the Cornish Main Line and serves the nearby town of Bodmin, Cornwall, United Kingdom. The station is west of , in the civil parish of St Winnow....

. Three years later another of the class, 3542, derailed at Penryn

Penryn railway station

Penryn station is on the Maritime Line from Truro to Falmouth Docks, and serves the town of Penryn, Cornwall. The services are operated by First Great Western.-History:The station was opened by the Cornwall Railway in 1863...

 and rolled down an embankment, killing the driver. Following this the whole class was rebuilt as 4-4-0

4-4-0

Under the Whyte notation for the classification of steam locomotives, 4-4-0 represents the wheel arrangement of four leading wheels on two axles , four powered and coupled driving wheels on two axles, and no trailing wheels...

 locomotives.

4-4-0 standard gauge

All forty 0-4-4T locomotives were rebuilt as 4-4-0

4-4-0

Under the Whyte notation for the classification of steam locomotives, 4-4-0 represents the wheel arrangement of four leading wheels on two axles , four powered and coupled driving wheels on two axles, and no trailing wheels...

 tender locomotives between 1899 and 1902.

Two locomotives, 3521 and 3546, were transferred to the Cambrian Railway in 1921 to replace locomotives destroyed in the Abermule

Abermule

Abermule is a village in Powys, mid Wales, located on the River Severn. The Montgomeryshire canal runs through Abermule, the canal is very close to the river.- Amenities :...

accident. They were allocated Cambrian numbers 82 and 95 respectively but these were never carried, the two locomotives being returned to the Great Western Railway with their original numbers when the two railways were grouped together in 1922.