Nathan Monitor Injector in 2.5"
Posted: Tue May 21, 2019 11:00 am
I started designing the 2.5" Monitors back in August 2014. I figured they would make a nice dummy body on a locomotive I hoped to build.
Well, going through Nathan drawings and looking over model injector designs, this project grew into a love for steam injectors that got a little out of control.
I've had a working prototype on my locomotive since before Eccentric Engineer ever sold an injector, but I've never been happy with its operation.
The injector part of it worked fine, but the getting the valves to seal properly and easily operating the handles was never to my satisfaction. This is the 4th, and I think, the final design of this injector. It's surreal seeing one built up that represents what the production run will look like. I've only ever seen all 56 parts together in CAD before now!
For the main steam valve (topmost valve), I've experimented with a 90 degree turn valve and a push-pull style valve, and neither worked great. So I went back to the drawing board and had a look at the real thing again. They use a double lead thread. So I decided to go one further and use a triple lead thread on the model. This means the handle goes from closed to fully open in just a hair over 1 full turn.
The trick with the primer valve (middle valve) is it doesn't have room to spin around more than half a turn, so it also features a triple lead thread. This opens it more than enough with just 1/4 turn. It also has a hexagonal key on the spindle, so that it can be easily rotated to a convenient location, depending on which side of the boiler the injector is on.
The water valve is just for looks (bottom), but it still has packing to give it some resistance so it stays wherever you put it. Control valves on the tender will be used to control water flow.
The delivery cone is threaded into the front casting, which unscrews from the overflow body. So removing the delivery cone is as simple as unscrewing the front piece. The steam and combining cone are threaded into the main body, and can be removed with a long 3/16" socket drive. They all come out through the front without disassembling the injector further. Which means different sized nozzles can then be threaded back in! I plan on offering two different delivery rates for these injectors. 5 pints (same as the Standard Injector) and 6.5 pints for larger 2.5" engines.
Stay tuned,
Anthony
Well, going through Nathan drawings and looking over model injector designs, this project grew into a love for steam injectors that got a little out of control.
I've had a working prototype on my locomotive since before Eccentric Engineer ever sold an injector, but I've never been happy with its operation.
The injector part of it worked fine, but the getting the valves to seal properly and easily operating the handles was never to my satisfaction. This is the 4th, and I think, the final design of this injector. It's surreal seeing one built up that represents what the production run will look like. I've only ever seen all 56 parts together in CAD before now!
For the main steam valve (topmost valve), I've experimented with a 90 degree turn valve and a push-pull style valve, and neither worked great. So I went back to the drawing board and had a look at the real thing again. They use a double lead thread. So I decided to go one further and use a triple lead thread on the model. This means the handle goes from closed to fully open in just a hair over 1 full turn.
The trick with the primer valve (middle valve) is it doesn't have room to spin around more than half a turn, so it also features a triple lead thread. This opens it more than enough with just 1/4 turn. It also has a hexagonal key on the spindle, so that it can be easily rotated to a convenient location, depending on which side of the boiler the injector is on.
The water valve is just for looks (bottom), but it still has packing to give it some resistance so it stays wherever you put it. Control valves on the tender will be used to control water flow.
The delivery cone is threaded into the front casting, which unscrews from the overflow body. So removing the delivery cone is as simple as unscrewing the front piece. The steam and combining cone are threaded into the main body, and can be removed with a long 3/16" socket drive. They all come out through the front without disassembling the injector further. Which means different sized nozzles can then be threaded back in! I plan on offering two different delivery rates for these injectors. 5 pints (same as the Standard Injector) and 6.5 pints for larger 2.5" engines.
Stay tuned,
Anthony