Hayward adjuster on GWR wagons - retrofit on older wagons?

[WhitleyP]

I couldn't find anything on this searching the forum, but apologies if that's my search skills at fault.

 

My question is, what approach was taken to retrofit older GWR d/c wagon brakes with the hayward adjuster, if any?

 

Was there any policy of adding these in as wagons came in for service? Or were non-hayward d/c brakes left as they were (perhaps only replaced if a major repair required a lot of the brake gubbins to be swapped out anyway)?

 

The Atkins et al. GWR wagon bible only refers to them being fitted to "most" new builds from WW1, and makes no mention of them being retrofitted to existing stock.

 

Cheers,

 

Simon