Lately, whilst cleaning up and renovating the pair of water tank filter valves, I've been pondering the purpose of a small tube on the left hand side of Sentinel 7109's water tank that is there in some photos but not in others.
Have a look at this:
|Sentinel 7109 at Shrewsbury prior to delivery, probably 1927|
(Photo courtesy John Hutchings, Industrial Locomotive Society)
|7109 Tube and valve highlighted|
|Missing 7109 Tube|
(Photo cropped from C Verrall 1964 original)
|Radstock Sentinel 7191 (wks no. 7588) showing its twin tubes|
(Photo cropped from R. G. Jarvis original, Richard Dagger collection)
Sentinel 7109 was originally supplied with an injector; however, it apparently did not work very well and was soon replaced by a Worthington Simpson type boiler feed pump mounted on the right hand driver's 'window ledge'. Hence the tube was there to feed the injector in the early photo but missing in the later photo.
So if an injector did not work for Sentinel 7109, why was one or more then fitted to the later Radstock Sentinels and left there?
That is the question!