Coupling plate dimensions - what size?

Dog Star

Western Thunderer
Here is a photo of a drawing on a page in "GWR Wagons" (Tourret et al, published by Tourret):-

016 (3).jpg


This drawing maps coupling plates to build period - I am interested in the dimensions of the trapezoid shown for the period 1900 to 1920. Can anyone provide either the dimensions or a reference to a drawing of the plate?

thank you, Graham
 
Top