Antique pump rebuild - advise needed

[FliesLikeABrick]

Antique pump rebuild - advice needed

Hello everyone,

While on vacation last week, a new project followed me home - an old pump with electric motor, from back in the woods behind a lakeside camp where it was their on-hand firefighting pump 50 years ago.

I have the motor running (old Century Electric Co repulsion start/induction run motor, ca 1947 1hp), and am now turning my attention to the pump.

The pump is from the 20s-30s (this electric motor retrofitted to the frame later). The main seal on the shaft seems to be a felt/wool packing impregnated with grease.


Pictures for context:





The part that I need input on and have not been able to make much progress on is a part that bolts to the frame at/around the pump's input.




The above picture is with the piece in question, a cast iron "flange" shaped piece, unbolted from the frame and tilted to the 2:00 position, that cup is normally pointing up vertically.

As you screw the top of the cup down, it pushes grease down into the journal around the shaft.


The end of this piece that faces towards the pump actually fits into the frame, compressing the packing inside; so it would make sense if this cup/grease mechanism was meant to inject grease into that area. However:
- It is on the far end of the cast component instead of closer to the seal
- This piece's ID has a step in it -- it is narrower towards the pump, and larger towards the motor. This means that any grease forced inwards will generally just ooze towards the motor.

Here are approximate measurements of the diameters in question:
- The shaft is 1.343"
- The narrower ID of the component in question is 1.382", this end faces the pump
- The larger ID of the component in question is 1.495", this end faces the motor and is the ID that has the grease cup/fitting on it

Here are some other pictures:

The cup with the cap off. In this picture it is not bolted in place, but this the location and orientation that it sits in



This is where it sits, with the camera facing towards the back of the pump. The bolts are still removed, the piece in question is slid back from the pump. Where the shaft enters the frame, you can see the darker grease-impregnated wool/felt bushing/seal


Above, the piece on the table - screwing the cap down pushes grease into the opening

So my questions:
- Can anyone provide some input on what this setup is meant to accomplish?
- Is something perhaps missing, like another wool/felt packing inside of this piece that would keep the grease from oozing towards the motor? I don't think so, since the OD is wider on that end and such packing would just be pushed out by the grease.


Of course any other input on this pump would be welcome.

 

[Oregon rock crusher]

I think what you are missing is pump packing that goes into the recess and is compressed by the gland nut. You put fresh packing in and tighten it up until it doesn't leak anymore. Rope pump packing comes in several diameters. Tightening the packing is a fairly routine task to keep the pump from spraying water out. Should be able to find a lot of info online about pump gland packing. Ed.

 

[MShaw]

From being exposed to pumps on fire trucks I would note that the packing should be adjusted so that there is a slow drip of water coming thru the packing. The keeps the packing lubricated and the puddle on the ground is of no concern on a fire pump used outdoors.

 

[FliesLikeABrick]

Thanks guys. Re-reading the thread now, I see that I may have done a poor job explaining and could use a visual reference of the diameters I was trying to describe.

Below is a cross-section to try and illustrate my confusion. Please forgive the quality, it's been 15 years since I drew something like this by hand (and I was better-equipped for it at the time). The drawing is not to scale.



The pump impeller shaft is a constant OD of 1.343". The component in question is the one with the grease cup screwed into it. As you can see, the larger ID of this piece is on the rear, away from the pump.

The other end of the component does indeed compress the packing around the impeller drive shaft. That packing is present, and this aspect of the component's purpose does seem clear.

The question is what the deal is with the larger ID at the back of the piece, away from the pump. Grease from the cup enters that portion, and would seem to have a lower path of resistance to exit out the back - instead of entering the packing.

If the component was a smaller clearance on the shaft it would make sense to be acting as a plain journal bearing on the shaft; and not unreasonably, being that it is cast iron on a mild steel shaft. However, there is a 0.112 difference in diameters between the shaft diameter and the rear ID of the component in question.

 

[95vette]

Hello, It is possible that the grease is there to provide a seal so the pump doesn't draw air around the packing.

 

[Oregon rock crusher]

Could be it was set up similar to this drawing with a lube ring between packing. Most of the old pumps I've been around did have a grease cup near the packing gland. Ed.

 

[FliesLikeABrick]

Hello, It is possible that the grease is there to provide a seal so the pump doesn't draw air around the packing.

This is an idea I hadn't considered

Could be it was set up similar to this drawing with a lube ring between packing. Most of the old pumps I've been around did have a grease cup near the packing gland. Ed.

I considered this - it is the logical explanation of what it is all for, and I came across a few drawings like the one you showed. However I still can't reason why the side of the packing gland facing the motor has a larger ID and is such a sloppy fit on the shaft.

The only way it works in my mind is if the impeller shaft has been altered in the past, perhaps when the electric motor was retrofit onto it.

Maybe the pump used to be driven by a substantially different power source/layout, and the additional bushing/support of the packing flange was important. However when it was driven by the motor, the additional support isn't needed as long as the motor is concentric with the impeller?

It still doesn't quite add up, because the motor is keyed to the impeller. If the impeller shaft was changed to make that possible (it appears to be welded into the center of the impeller), it would mean the entire shaft was replaced -- or it was a larger diameter on the input side, someone turned it down (for some reason), then managed to cut a keyway inside to make the motor setup work.


The drawing you cited leaves me with the feeling that pieces are missing from my setup. If there was some kind of seal that attached on the input side of the packing flange, the whole thing starts to make a bit more sense.

Maybe the answer is to someday counterbore the input side of the flange and press in a bronze bushing that closes the gap a bit, or at least make a seat that can accept a seal.