Bottle jack seals

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murraym

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Hello all. I am attempting a rebuild on an old 12 ton bottle jack. Does anyone have a good resource for cs style cup seals? I am having a difficult time trying to find one with the right dimensions.
 
Looks like this. I think i am using the correct term.
 

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That looks like a leather seal to me. A search for leather cup seal turns up some options. McMaster has some leather seals, but I didn't see any cups like yours.

Edit to add that if it is leather it can probably still be used. Soak it in some clean oil and find a way to hold the lips of the seal spread out a bit....Leave for a few days and Robert is your mother's brother....
 
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paradox_pete said:
That looks like a leather seal to me. A search for leather cup seal turns up some options. McMaster has some leather seals, but I didn't see any cups like yours.

Edit to add that if it is leather it can probably still be used. Soak it in some clean oil and find a way to hold the lips of the seal spread out a bit....Leave for a few days and Robert is your mother's brother....
Click to expand...
Is this an application where leather would have been used? I agree after closer inspection it definitely could be leather. I'll try soaking in clean oil.
 
Or do you think i could just groove the poison and use an oring?
 
murraym said:
Or do you think i could just groove the poison and use an oring?
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Bottle jacks often work a pressures higher than O-rings are rated for. Some work at a maximum of 10,000 psi. You can calculate the pressure by calculating the surface area of the piston (1/2 the diameter of the piston x 1/2 the diameter of the piston x 3.1416) (phi x r squared) Then divide this number into 24,000 (number of pounds in 12 tons).

90 durometer O-rings are pretty tough when used with an appropriate back-up ring. If your psi calculates out to 2,000 or so, you can go to a good seal supplier and get their recommendation. Many will not be willing to supply anything but original parts for lifting equipment.
 
Provincial said:
Bottle jacks often work a pressures higher than O-rings are rated for. Some work at a maximum of 10,000 psi. You can calculate the pressure by calculating the surface area of the piston (1/2 the diameter of the piston x 1/2 the diameter of the piston x 3.1416) (phi x r squared) Then divide this number into 24,000 (number of pounds in 12 tons).

90 durometer O-rings are pretty tough when used with an appropriate back-up ring. If your psi calculates out to 2,000 or so, you can go to a good seal supplier and get their recommendation. Many will not be willing to supply anything but original parts for lifting equipment.
Click to expand...
Please forgive me but i don't understand your Calc. Is phi suppose to be psi? If so, the i just solve for that right? Is it 1/2Dx1/2dx3.14 or just 1/2Dx3.14? Thank you for the comment regarding lifting equipment. I don't think i will proceed with this regardless of how the Calc turns out but i would like to know for my own knowledge. Thank you
 
murraym said:
Is this an application where leather would have been used? I agree after closer inspection it definitely could be leather. I'll try soaking in clean oil.
Click to expand...
I think leather would have been the most common seal for this sort of application pre-war. I know it was used in hydraulic cylinders, water well pumps and other applications well into the '50's at least.

If the leather is crumbling or disintegrating then it needs to be replaced, but if it is still pliable it can be re-used. As the pressure in the jack builds, it will force the lips of the seal tighter against the cylinder. It really just needs to be tight enough to provide an initial seal so the pressure can start to build.

-Pete
 
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