GWR 645 and 1501 Classes explained

Powertype:Steam
GWR 645 and 1501 Classes
Designer:George Armstrong
Builder:GWR Wolverhampton Works
Builddate:1872-1881
Totalproduction:108
Driverdiameter:4feet
see text for variations
Cylindercount:two
Cylindersize:16x
see text for variations
Operator:South Wales Mineral Railway
Carmarthen and Cardigan Railway
Great Western Railway
British Railways
Retiredate:1928-1949
Disposition:All scrapped

The GWR 645 and 1501 Classes were two closely-related classes of designed by George Armstrong and built at the Wolverhampton railway works of the Great Western Railway (GWR). Thirty-six, the 645 Class, were constructed between 1872-3, of which three were built for the South Wales Mineral Railway (SWMR), two for the Carmarthen and Cardigan Railway (C&CR) and the remainder for the GWR. In essence, they were saddle tank versions of his GWR 633 Class of 1871. From 1878, a further 72, the 1501 Class, partially enlarged, were added. Unlike the originals, these had full-length saddle tanks from the start.

Construction

The whole class was delivered in nine lots, as follows:

Three of the un-numbered engines plus No. 767 were sold to the SWMR, and the other two plus No. 655 to the C&CR. The latter three returned to the GWR in 1881, becoming Nos. 902-904.

Dimensions

When built, they had 4feet driving wheels (later 4feet due to thicker tyres). The principal visual differences between the two classes were that the 645 class had short tanks and no cabs, whereas the 1501 class had cabs and full-length tanks. Other differences included:

645 Class: saddle tanks only cover the boiler and firebox; cab has only a front weatherboard and low side sheets; rear end of frames 5feet from rear axle; cylinder bore 16inches; heating surface 1300abbr=onNaNabbr=on; tank capacity 980impgal. Half-cabs were added a few years after construction.

1501 Class: saddle tanks are full-length, and cover the smokebox; cab has roof and full-height side sheets; rear end of frames 5feet from rear axle; cylinder bore 17inches; heating surface 1145square feet; tank capacity 1120impgal.

From 1918 all but eight of the class were rebuilt with Belpaire fireboxes and larger, pannier tanks extending over the smokebox, and the 17inches diameter cylinders became standard.

Use

Most of the 645s and 1501s were allocated to the Northern Division of the GWR. Between 1910 and 1922 three more of them, Nos. 1806, 1811 and 1546, were transferred to the SWMR, and others too went to South Wales. Most were withdrawn in 1930s. Nos. 1531, 1532, 1538 and 1542 passed briefly into British Railways ownership, but all were withdrawn by December 1949. None have survived into preservation.

See also

References