The Home Machinist!

crackerjackhoghead wrote:Can the Superscale injectors be trimmed like a full size injector or are they all or nothing?

I know the Chicago model can.
I never tried it with the economy injectors

Trimmed???

control flow rate..

or are they simply off / on?

Steven E. Kuhn wrote:Trimmed???

also known as throttling

With most injectors, you can throttle down the rate that water is being injected.
The superscale Chicago injectors have an operating input water valve to find tune the injector to the boiler size
I currently have one wide open and the other one a few turns from closed
You can also trim the rate by closing down the water valve on the tender.

Is each end of the double ram pump plumbed independly with seperate feeds, bypass and boiler checks for reducency?

The double ram is nice looking alternative to increasing piston diameter and the resultant forces that go with it.

Still should have a water source that works when the engine is not in motion.

Rob

Had no problem with my allen axle pump keeping enough water in boiler if anything it supplied to much,but i didnt use a bypass valve,instead i put a valve on intake side,that way u diont load up pump pumping water u dont need back into tender.it took a few runs to get valve adjusted but i almost never used injector unless the loco sat a while with safetys popping off and on . the reason axle pumps lock up is lubrication,i put a grease fitting on mine on end of body near the pcking gland ,.allen prints have no packing,i threaded end of pump body and made big nut with teflon between. it never seized up.expecting a pump not to leak without a packing gland is crazy

what is the opinion on smokebox preheaters? also if you have 2 pumps do you plumb them together in parallel?

I had smoke box heater on allen,simply copper tube rolled into whiskey still type loop,went from. pump discharge into smokebox,then into a check valve then into boiler,never gave me any trouble,have heard of loop making steam and being blamed for pump losing iits prime,never happened to me,prob because of check valve at pump head which some dont have relying only on check inside smokebox.

Regarding the Allen pump packing design. The packing is an o-ring on the end of the piston, which means to seal well the bore of the pump needs to made to tight diameter tolerance and surface finish. This is not the most pratical of designs. As mentioned a packing at the inlet would be more prudent.

I have a 3/4" engine and the design is an o-ring packing in the housing bore. This makes the sliding seal surface the piston, which is much easier to machine and polish to tolerance than the bore. Also the seal in near the inlet so it seems to keep dirt out. The other advantage is the piston can be repolished or replaced much easier if it gets damaged or worn, but this has not been an issue yet, engine is 28 years old. The housing is brass or bronze and the piston stainless steel. The o-ring sits in a groove machined in the bore near the end where the piston enters it. The only critical surface finish in the bore is the o-ring groove.

Also replacing the packing is easy, just pull pin form the end of the piston at the eccentric, slide out the piston, pull o-ring out with a pick and put it back togethner with a new o-ring. I have replaced the o-ring a couple of times, not becuase it failed, but because I was doing something else and it was convenient to replace it while things were apart.

Rob

I recently observed a gentleman operating an engine equiped with two injectors only, no hand pump and no water pump. The water level got low, pressure started to drop, and he then couldn't get more water in because there wasn't enough pressure to run the injectors.

Thus, the only option was the drop the fire and start over. Had he equipped the engine with an axle pump or a handpump, he might have been able to get out of the situation. True, injectors are great when they work but if they fail it is nice to have another way to get water in. The axle pump is a pretty simple method overall.

A friend has an Allen ten-wheeler and aside from replacing the O-rings every season (he does it whether they need it or not) it works fine.

no knowing what injectors he had, i can only add my Superscale Chicago injectors will inject as low as 40 psi.
just need to throttle back the water.

but i would be more worried he let the engine get to this condition in the first place.

more the marry-er but two injectors is enough if you pay attn to what your engine is doing.
that's just my two cents.

Benjamin Maggi wrote:I recently observed a gentleman operating an engine equiped with two injectors only, no hand pump and no water pump. The water level got low, pressure started to drop, and he then couldn't get more water in because there wasn't enough pressure to run the injectors.

Thus, the only option was the drop the fire and start over. Had he equipped the engine with an axle pump or a handpump, he might have been able to get out of the situation. True, injectors are great when they work but if they fail it is nice to have another way to get water in. The axle pump is a pretty simple method overall....

Injectors made for, and used in the hobby for the past 35 years.... Ohlenkamp, Supercale.... are extremely reliable.

The key, is to learn to fire your engine's boiler so you're not put into that position. Don't let the steam pressure get so low that the injectors won't lift..... And don't let the water level drop to dangerously low level where putting a lot of cold water into the boiler will drop steam pressure to where the injectors won't work.

If having a problem with an injector(s), you should be heading back to the steaming bay trying to try to remedy the situation and not out on the main line to begin with.

Using an axle pump??? Ugh! Now, using a crosshead pump(s), if one was used on the prototype engine that's been modeled? That's another matter.

LL