Large Scale Central

ACC 3-cylinder shay eccentric push rods

Electronics Live Steam
#1

Hi folks,

Has anyone ever replaced the vavle pushrods on an ACC 3 cylinder shay? I’ve seen it done with ball bearings on the 2 cylinder shay…BUT I really don’t think you can slide a bb race over the forward engine crank to access that center eccentric.

All 3 of the eccentrics are worn out in this manner…the brass cylinders on the drive shaft are okay, but the brass inserts in the pushrods have gone egg-shaped. The engine still runs very strongly in reverse, but forward gear is very rough. The time has come to fix it up, or move it out.

My biggest question…Can I remove the old valve pushrod without taking the forward crank (press fit) apart? Is there a way to “twist” the pushrod up over and out the other side of the crank?

If I can do this, I figure I will make a new set of pushrods using the originals as a template. If possible, I could just re-bush the original rods. It won’t be an upgrade, but it should at least run as good as new!

Otherwise, I may consider cutting the old one off and building a two-piece shackle much like the piston crank.

Or I could sell the whole thing as is…

Or I could keep the boiler for a new project and part-out the rest of the usable components…

#2

Nope, its required to be disassembled for repairs. I couldn’t see how you can get the eccentric off without pulling the crank apart. As Accucraft is preparing to get the production of the new 3 cylinder shay going, it would be in your interest to get a replacement crankshaft assembly OR a complete motor. If interested its something I could try to arrange.

As to repairing that one, once you have the crank apart is just making a new collar that goes onto the eccentric of bronze not brass. Thought I had some photos of the parts from my friends Edrig but I cant fined them.

#3

Hi Jason,

Thanks for the reply! I took the whole assembly apart over the weekend. It turns out the eccentrics were worn as well. Since ACC has no parts for this engine at this time I decided to turn down the old eccentrics and to make new eccentric straps from brass.

It appears the cranks are silver soldered, or brazed, so I elected to leave them alone! Thankfully, the center eccentric is two-piece and comes apart. The old eccentric strap can then be threaded thru the cranks to release it from the shaft. I was able to turn all 3 eccentrics down to .450in, (I think). I polished them up, nice and mooth as they were originally. Next I drilled, bored and honed out 3 new eccentric straps. I used the milling machine and bench grinder to shape the new straps using ACC’s stainless straps as a template.

I’ll post some photos of my re-build this evening…I think you’ll like the look of the new lower-profile brass straps!

#4

I had my Accu Forney eccentrics redone with ball bearings. If you need some of the ball bearings let me know. I have more then enough.

#5

Thanks Shawn,

I would be very interested in buying some, but…If I did, I could only do two of the three eccentrics in BBs because I think they are too wide to slip through the crankshaft to access the center eccentric. The thin eccentric strap and bushing are thin enough to slip through.

#6

Rockwall Canyon Jeff said:

Hi folks,

Has anyone ever replaced the vavle pushrods on an ACC 3 cylinder shay? I’ve seen it done with ball bearings on the 2 cylinder shay…BUT I really don’t think you can slide a bb race over the forward engine crank to access that center eccentric.

All 3 of the eccentrics are worn out in this manner…the brass cylinders on the drive shaft are okay, but the brass inserts in the pushrods have gone egg-shaped. The engine still runs very strongly in reverse, but forward gear is very rough. The time has come to fix it up, or move it out.

My biggest question…Can I remove the old valve pushrod without taking the forward crank (press fit) apart? Is there a way to “twist” the pushrod up over and out the other side of the crank?

If I can do this, I figure I will make a new set of pushrods using the originals as a template. If possible, I could just re-bush the original rods. It won’t be an upgrade, but it should at least run as good as new!

Otherwise, I may consider cutting the old one off and building a two-piece shackle much like the piston crank.

Or I could sell the whole thing as is…

Or I could keep the boiler for a new project and part-out the rest of the usable components…

Jeff

i have a two cyl. shay that needs a rebuild can you point me in that direction ?

Richard

#7

Rockwall Canyon Jeff said:

Thanks Shawn,

I would be very interested in buying some, but…If I did, I could only do two of the three eccentrics in BBs because I think they are too wide to slip through the crankshaft to access the center eccentric. The thin eccentric strap and bushing are thin enough to slip through.

Send me a PM with your afrress. Ill send you three at no cost.

#8

Richard Beverly said:

Rockwall Canyon Jeff said:

Hi folks,

Has anyone ever replaced the vavle pushrods on an ACC 3 cylinder shay? I’ve seen it done with ball bearings on the 2 cylinder shay…BUT I really don’t think you can slide a bb race over the forward engine crank to access that center eccentric.

All 3 of the eccentrics are worn out in this manner…the brass cylinders on the drive shaft are okay, but the brass inserts in the pushrods have gone egg-shaped. The engine still runs very strongly in reverse, but forward gear is very rough. The time has come to fix it up, or move it out.

My biggest question…Can I remove the old valve pushrod without taking the forward crank (press fit) apart? Is there a way to “twist” the pushrod up over and out the other side of the crank?

If I can do this, I figure I will make a new set of pushrods using the originals as a template. If possible, I could just re-bush the original rods. It won’t be an upgrade, but it should at least run as good as new!

Otherwise, I may consider cutting the old one off and building a two-piece shackle much like the piston crank.

Or I could sell the whole thing as is…

Or I could keep the boiler for a new project and part-out the rest of the usable components…

Jeff

i have a two cyl. shay that needs a rebuild can you point me in that direction ?

Richard

Richard some n the other site did write up on redoing the eccentrics etc… It was for a ruby but the Shay uses the same eccentrics and cylinders.

Here is the link

http://www.mylargescale.com/Community/Forums/tabid/56/aft/128956/Default.aspx

#9

http://www.mylargescale.com/Community/Forums/tabid/56/aft/128956/Default.aspx

Rick, since you have the 2 cylinder shay, I would try the BB method. Sealed bearings will prevent sand particles from causing wear again. Bill used a brass ring to fit over the ball bearing and then silver soldered the original connecting rod to it. Personally, I would go ahead and make the ring as he shows, but instead of cutting the original eccentric strap to recycle the connecting rod, I would simply make a new one out of brass. If you do this, you wont have to solder dissimilar metals, and perhaps soft solder would be plenty adequate.

There does not appear to be an easy way to do this on the three cylinder (crankshaft is brazed together). I’m having serious PC issues at the moment, so I havent been able to post pictures of what I had to do with mine.

#10

Shawn Viggiano said:

Rockwall Canyon Jeff said:

Thanks Shawn,

I would be very interested in buying some, but…If I did, I could only do two of the three eccentrics in BBs because I think they are too wide to slip through the crankshaft to access the center eccentric. The thin eccentric strap and bushing are thin enough to slip through.

Send me a PM with your afrress. Ill send you three at no cost.

Thanks Shawn. I truley appreciate your generous offer, but I’ve already got the engine back together and running beautifully! The engine sounds so much better now that the valves are going up and down in their intended range. It’s rather amazing the engine ran at all before I installed my home-brew eccentric straps.

#11

thanks Jeff i will look into it. and thanks Shawn

richard

#12

RCRR#7 without pistons

RCRR #7 sans pistons

(http://lh4.googleusercontent.com/-EV7iHp9s47o/Ur5FuFFFgPI/AAAAAAAABwA/gIDC3_zMSFA/s640/IMG_0128.JPG)

Pistons, crossheads, and pushrod assemblies

(http://lh5.googleusercontent.com/-jGMM1I0NwpU/Ur5Fvp8MIfI/AAAAAAAABwg/skKxcREufcY/s640/IMG_0139.JPG)

Crankshaft with original eccentric straps (stainless steel)

(http://lh4.googleusercontent.com/-cP83hbLPzNI/Ur5G4bKMV8I/AAAAAAAABxY/LJ1SJP6KsW8/s640/IMG_0141.JPG)

A quick guide to remind me how the eccentrics and cranks align for re-assembly

#13

(http://lh6.googleusercontent.com/-4JPJqWWetJU/Ur5FuuGFLkI/AAAAAAAABwI/F69UXLrU1GM/s640/IMG_0129.JPG)

Oops sorry about the steam oil snots…but an interesting view anyways.

The offending eccentric straps have been removed. The nastyness on the paper towel is grime removed via WD40 from the components of the whole assembly.

(http://lh5.googleusercontent.com/-j_oK0q14k8k/Ur5Fwk2sM6I/AAAAAAAABw0/oxr581dS9k0/s640/IMG_0144.JPG)

Brass bushing removed from stainless strap. You can see (hopefully) it’s worn right through on the top.

(http://lh5.googleusercontent.com/-kKAaNy-BzsQ/Ur5FWhdYq7I/AAAAAAAABxE/uemBFTk6tzA/s640/IMG_0160.JPG)

Brass replacement straps made by yours truly. These straps do not have bushings, so they are a one and done sort of deal. The previous brass bushings survived 10years or so…So for 2 hours work, I wont mind making new straps again in ten years.

(http://lh4.googleusercontent.com/-D_-nla6zUHg/Ur5FXXnQ5TI/AAAAAAAABxM/lbaCN4ur_I0/s640/IMG_0161.JPG)

I actually steamed her for a good hour today, despite 30deg temperatures. I had to make a few adjustments to the eccentrics while she was hot…which is always exciting. Although it’s not at top performance, she’s already running far better than she was a week ago. I haven’t had smooth and plentiful power in forward gear for a long time.

#14

Pictures really are worth 1000 words. Now I completely understand what you did. Also glad to hear it took 10 years to wear out. At the level of use my ACC Shay gets, I’ll probably get 15-20 years out of mine :]

Nice work!

#15

Thanks Jon,

I also think I will be more aware of cleaning the loco periodically. Now that I’m not afraid to pull the crank shaft out, I should really make an effort to clean and lube everything after messy outdoor runs…especially if there is an off-track excursion!

#16

Jason, in view of the total lack of ANY 3-c Shay spares here in UK, I’d be very interested to know about the replacement crankshaft/valves assembly.

tac

#17

Its too bad accucraft does not make replacements, especially since it seems the eccentrics are the first to go. I got about 3 years on my Forney before the eccentrics wore but that’s with a lot of use and not cleaning. Now I clean them after every run.

Great pictures and nice work.

#18

jeff i see you pulled the pistons to did you put new o-rings on all so?

excellent pics.

richard

#19

Hi Richard,

No, I actually left the orginal piston rings installed. I got a bit impatient and wanted to see if my new parts worked. The whole engine needs new seals especially between the valve chests and cylinders. I suspect the next time we are buried in snow I may take the engine apart to finish the job. For now…the engine will run as is. The o-rings were still fairly soft at least.

#20

tac Foley said:

Jason, in view of the total lack of ANY 3-c Shay spares here in UK, I’d be very interested to know about the replacement crankshaft/valves assembly.

tac

Tac Contact me directly. Ill find out about getting some things.