Injectors

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Keith T-N
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Injectors

Post by Keith T-N » Thu Jul 23, 2020 8:39 am

Hello, I recived this about Injectors from Geoff Moore by email and post it on his behalf,
Keith Editor GL5 Turnout.

I have two injectors on my P1 which have been on the engine since I built it but they have not been entirely reliable.
Upon taking a close look at them recently I discovered that one had a feed pipe on the tender that had an internal restriction. That was easily rectified so I now went back to my original drawings of the injectors. The RH oneis situated immediately under the cab floorboards as the traditional position is fully occupied by the booster. The RH live steam one on the full size engine is mounted directly on the backhead [called the faceplate by the Doncaster drawing office] so that could not be used on the model.
The difficulty here is that when the water is low in the tender it can be well below the injector so the injector has to lift the water.

The LH injector on the full size is a Davies and Metcalfe exhaust steam class F and is mounted on the LH trailing frame,
immediately in front of the cartazzi axlebox. I made a model injector to scale dimensions and details externally but it is a normal model working one internally.

I have decided to retain the two bodies but to replace the cones with throat sizes as recommended by Bob Bramson. In trying to
marry his sizes with my original designs which are based on that by Basil Palmer I have come across a slight conundrum.

The middle part of an injector is the Combination cone. It has two parts but I find there is variation in what those two parts are called
which is not at all helpful!

Please can someone give some clarification ?

With the part with the throat on the RH end and steam flow left to right,

Laurie Lawrence - draught - forcing
Derek Brown - lifting - Forcing
Ted Crawford - mixing - forcing
Basil Palmer - draught mixing
Bob Bramson - - mixing

There may be others which could be added to the list.

Yours,
Geoff. Moore
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