Leister engine

[Brian Rupnow]

This week I had a visit from an 87 year old gentleman who has a 98 year old, 5 HP Leister gasoline engine. This engine had a combination fuel and oil piston style pump which has two 0.640 diameter brass pistons sliding in brass cylinders and driven by cams on the engine. Each cylinder has a reduced diameter section which he informs me his father used to pack with butchers cord soaked in grease to provide a good seal to make the pump work well. He said that of course this didn't last very long, and he wanted to know if I could suggest an alternative solution. Since the pistons are two peice construction, I can machine an aluminum ring to fill the gap which they originally packed with string and grease and machine an o-ring groove in the aluminum. I know that o-rings are made for both static and dynamic applications, and this seems to me to be a reasonable solution. I just don't know how well a standard Buna N type o-ring stands up to gasoline. Any suggestions?---Brian

 

[old-and-broken]

http://www.metrogasket.com/o-rings/material_selection_guide.htm

have a look. lots of charts.

and BUNA-N is very good for use with automotive gasoline.

 

[Brian Rupnow]

Thanks Old and Broken. I will call Hercules o-ring (about 5 miles from where I live) on Monday and get their recomendations for the correct size of o-ring and the size of groove I put in my aluminum part when used in a dynamic application.---Brian

 

[idahoan]

Hi Brian

This is a pretty good resource for O-ring gland design.

http://www.columbiaerd.com/gland_design.html

Dave

 

[old-and-broken]

For uses by model builders, there are really only two types

NBR - or Buna-N rubber
Good for all common hydrocarbon fuels, excepting Benzene, Toluene, and Xylene. Perfect for Diesel, gasoline, kerosene, butane and propane, and alcohol.
Not so good with steam.

HNBR - or Hydrogenated Buna-N rubber
NOT good for gasoline etc.
EXCELLENT for steam up to 350 degree F
HNBR is also more expensive than NBR

Shore hardness is available from 70A to over 90A

Harder rings have better moving friction resistance, while softer ones are good for static seals and gasketing applications.

 

[old-and-broken]

Shore hardness is available from 70A to over 90A

Harder rings have better moving friction resistance, while softer ones are good for static seals and gasketing applications.

 

[old-and-broken]

? what It was supposed to be appended to my first answer and not made into a second reply

Oh well, I use technology but I never understand it.

 

[Brian Rupnow]

I found an hours spare time today to give some attention to this Leister or Lister engine.(I'm not sure what the old fellow called it). Basically, there are two plungers side by side in a brass housing that are moved up and down by a pair of cam lobes. The plungers were in really rough shape--lots of vice grip marks on them, and any packing material was long gone. They were bound up severely in their bores. I put the plungers in the lathe and cleaned them up with some fine emery cloth. The plungers are a two part affair, with the largest part being a diameter 0.640" with a 1/4" tail that passes down thru a seperate .640 diameter part . The "packing" whatever it was originally fit in the gap between these two peices. There is a compression spring and a 5/16" check ball in the bottom of the bores---the spring fits around the 1/4" tail and keeps a constant pressure on the ring to keep the packing in place. I machined up 2 aluminum rings 0.638" dia. with a groove for a 1/16" Buna N o-ring and a 1/4" reamed hole in the center. Will they work?---darned if I know, but the old fellow got them free so he can't complain too loudly.

 

[Brian Rupnow]

I got a phone call about 10 minutes ago from the old fellow who owns the Leister or Lister engine. He has installed the pump with the new parts I made on the engine, and it is running very well. Nice end to a short story.---Brian

 

[AussieJimG]

Well done Brian, a very imaginative solution to the problem.

Jim

 

[skyline1]

This sounds like a Lister Engine I live about 1/2 Mile from Listers works or what's left of it in Dursley. Like many fine companies it went from about 2000 people to about 30 in about 10 years. Now it's just a "screwdriver" outfit testing and packing "Cr** from India" (their employees words not mine) It was a vast place at one time with their own Foundry, Machine Shops and just about every allied trade you could think of, they even had their own fire brigade !

Regards Mark