gland packing

[Belgian1979vette]

This is a bit off, but maybe someone here can help me.

As some of you know i'm restoring an old dyno that I purchased. I'm at the stage of reassembling the housing after the shaft was redone and balanced. The shaft is sealed in the housing by way of gland packings (rope type seal, packed in graphite).

The shaft itself had a problem in that one of the surfaces where the bearing sits was out of round. This caused the bronze bushing on the shaft to touch the housing in some instances when in operation. I had this corrected, but when trying to reassemble seems that the piece that is going into the housing were the rope seals sit (and that is used to compress the rope seals), is smaller than the bore itsself on the side where the out of round problem was. The bore thus is somewhat larger and if i'm correctly I will probably never get a good seal here. I suppose the problem with the bearing somehow also caused problems at the gland packings and to enlarge this bore in some way.

Any ideas on how to solve this. I already used a filler to correct any minor surface imperfections in this bore. But the amount i need to put in a approximatly 2mm all around, which makes it difficult to get everything perfectly round again after sanding.

Any input is greatly appreciated.

Thanks

Yves

 

[TimAT]

Pictures?

No idea how that's put together. But in the marine world the thru-hull fitting for an inboard, there's a bronze bushing on a flex coupling with the packing a forward of it. Common misconception of a packing gland like that is that it is not supposed to leak. Correct installation is 3-5 drops per minute. That keeps all the bushing, shaft and rope seal lubed and cooled.

 

[Grampy]

Go for it.

Back in the day I did some instumented studies of how the axial gland load was transfered as a radial sealing force along the depth of the packing box. This type of seal is common in many industrial applications and we were working in nuclear power where leaks are sort of a no-no. The short version is just tighten up the gland. The additional gap will result in a little more extrusion of the packing but you will get a seal.

You might read some articles or maintenence manuals on pump packing glands to get an idea for proper grade of packing material for a dynamic applications and leak rates.


Grampy

 

[Belgian1979vette]

Back in the day I did some instumented studies of how the axial gland load was transfered as a radial sealing force along the depth of the packing box. This type of seal is common in many industrial applications and we were working in nuclear power where leaks are sort of a no-no. The short version is just tighten up the gland. The additional gap will result in a little more extrusion of the packing but you will get a seal.

You might read some articles or maintenence manuals on pump packing glands to get an idea for proper grade of packing material for a dynamic applications and leak rates.


Grampy

Thanks,

Seen this was for hot water and high rpm's. They advised me to use glands of the graphite with asbestos typ.

 

[Grampy]

TFE also available

The Graphite/asbestos mix is a very standard packing material and you should have no problems. Although my dyno experience is limited to a little Go Power unit from my Formula Super V work back in the day I would expect in the dyno application that the water would not get all that hot. We used a garden hose. If you ever want to change it out, braided square TFE packing is available, would work at temps up to about 200*C and it's kinder to the shaft.

Grampy