Author Topic: Corliss query  (Read 163 times)

Offline astroud

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Corliss query
« on: September 08, 2019, 09:00:00 AM »
Actually I think this relates to any cross head engine but I have started work on an MEM Corliss and have a query about the piston rod and crosshead guidance. Is it usual to have close fits for the piston in the cylinder, the piston rod through the cover and gland and then the cross head slider in the guide ? I doubt my ability to get everything aligned to not cause some binding.
I have in mind to make a clearance for the rod through the cover and gland so it is accurately guided by the piston and the slider only. Otherwise I could make the cover with clearance holes to fix it to the cylinder to allow assembly alignment.
Looking at the MEM drawings there is no clearance anywhere and it seems it is expected to get everything aligned, maybe that is what I should aim for and worry about binding if it occurs.

thanks  Andrew

Offline vcutajar

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Re: Corliss query
« Reply #1 on: September 08, 2019, 11:56:47 AM »
Hi Andrew.  These are just my thoughts.

Even if you get everything perfectly aligned, the packing in the gland nut might cause binding when the gland nut is tightened.


If I remember correctly, I had some binding in mine.  I don't know if it was the piston rod or the packing which was causing the binding.  My solution was to just unscrew the gland nut just enough to remove the binding and it worked perfectly.

Vince

Online crueby

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Re: Corliss query
« Reply #2 on: September 08, 2019, 02:20:23 PM »
I have had the same experience as Vince. The recent engines I did, used o rings for the gland, and drilled the gland holes oversize so the rod would not bind there, and just be guided by the piston head and the crosshead.

Offline astroud

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Re: Corliss query
« Reply #3 on: September 08, 2019, 04:12:17 PM »
Thanks both that makes sense  I will be using an O ring for the gland so it should be OK making the holes slightly oversize and I can focus on getting a good fit for the crosshead without fear of binding

Andrew