Editing GWR 3252 Class (section)

===Cylinders and valves===
[[Slide valves]] were fitted underneath the cylinders, and were driven directly by eccentrics on the leading driving axle through [[Stephenson valve gear]].<ref name=OSN27/><ref name=OSN10>{{harvnb |Nock |1977 |p=10}}</ref> This position had the advantage that, when the regulator was closed and steam pressure shut off, the valves would drop away from the steam ports, thus reducing wear on the valves and port faces. Dean's earlier designs had used slide valves mounted vertically between the cylinders; the new position allowed an increase in [[cylinder (engine)|cylinder]] [[Bore (engine)|diameter]] from {{convert|17|in|mm|0|abbr=on}} to {{convert|20|in|mm|0|abbr=on}} in the Armstrong Class.<ref name=OSN11>{{harvnb |Nock |1977 |p=11}}</ref> The Dukes had {{convert|18|in|mm|0|abbr=on}} diameter cylinders, possibly due to [[permanent way]] weight restrictions and a reduced supply of steam from the Dukes' smaller boilers.<ref name=OSN17/>

{| class="wikitable" style="text-align:center;"
|+ Table of orders and numbers{{sfnb|Allcock|Davies|le Fleming|Maskelyne|1968|p=28}}
! Year !! Quantity !! Lot No. !! Works No. !! Locomotive numbers !! Notes 
|-
| 1895 || {{0}}2 || {{0}}97 || 1431–1432 || 3252–3253 || align=left | 
|-
| 1895 || {{0}}8 || 101 || 1493–1500 || 3254–3261 || align=left | 
|-
| 1896 || 10 || 102 || 1501–1510 || 3262–3271 || align=left | 
|-
| 1896–97 || 20 || 105 || 1531–1550 || 3272–3291 || align=left | 
|-
| 1898–99 || 20 || 113 || 1682–1701 || 3312–3331 || align=left | 
|}