Tuesday, 14 June 2011

Sentinel 7109's Cab-Mounted Boiler Feed Pump (BFP)

(If you want to skip to the video, click here). 

A replacement twin-cylinder Worthington-Simpson boiler feed pump was purchased from Richard Vincent of Vincent Engineering at Henstridge Airfield, Templecombe, Somerset. 
WS Boiler Feed Pump as found
It had clearly been lying about for a while and was "in need of some attention". (The word "some" is used loosely here!).
Steam cylinders as found
Slide valves as found
Water pump valves as found
The WS boiler feed pump is a steam engine in its own right. Steam and water cylinders have had to be carefully scraped clean, the outside cleaned and painted plus a lot more. 
BFP - looking like new again!
Maker's plate showing a 50 in the serial number
to indicate the 1950 date of manufacture
video

Like the main engines, the pump will chug away merrily on compressed air when asked to, albeit without any water to pump as yet. (Note: Adobe Flash player will be needed to run the video (indicated by a blank image above).
Water pump piston rings(1) 
Water pump piston rings(2)
Prior to testing as a water pump, I'd expected the pump to be able to suck or blow air; however, this is not the case and air can merrily be blown through it either way with no effort at all. Something is clearly amiss!
Cut-away drawing of 3x2x3 WS Pump
Each water pump piston has four rings of a cloth reinforced material as in the pictures. Each ring has a split so I'm expecting them to expand to a good fit when pressurised by pumping water - well let's hope so anyway.
BFP Displacement Lubricator
A displacement lubricator has been obtained from Richard Nixon of the Sentinel Drivers' Club (not the original tricky one) and has been restored to ensure the pump will be able to work with its own steam oil supply. 

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