Large Scale Central

Ok This time Valve gear linkages

Modeling
#1

So my ignorance of Locomotive design and function is really starting to show. Guess you don’t have to know how they work to love them.

I need to run the linkages from the Johnson bar to the two steam chests. As I started to do this I realized I have no idea how they are attached, or what they do really. I know when you push the johnson bar forward then the loco goes forward. When it is in the middle its in neutral and when you pull it back it goes in reverse. So does that just extend through a slot in the floor then hook to a rod that goes forward to a pivot rod that actuates two levers one on each side that pushes a rod in and out of the steam chest?

When I googled it I came up with a very scary all automatic sort of thing that was hooked to the driver that was very confusing. This is an 1880’s small loco. I think this would be as simple as it gets. So what should this look like?

Devon

#2

Early locomotives used Stephenson valve gear, see http://en.wikipedia.org/wiki/Stephenson_valve_gear Since most of the mechanism is located between the frames you really only need to duplicate the reach rod and the eccentric unless you want to duplicate the mechanism between the frame.

#3

Gary Buchanan said:

Early locomotives used Stephenson valve gear, see http://en.wikipedia.org/wiki/Stephenson_valve_gear Since most of the mechanism is located between the frames you really only need to duplicate the reach rod and the eccentric unless you want to duplicate the mechanism between the frame.

No at this point I have no intention of duplicating anything inside the frame rail. Bu with me you never know (how could you because I never know). Thanks for the link. I will at least learn about them. Then i can model something that at least looks plausible.

#4

Gary Buchanan said:

Early locomotives used Stephenson valve gear, see http://en.wikipedia.org/wiki/Stephenson_valve_gear Since most of the mechanism is located between the frames you really only need to duplicate the reach rod and the eccentric unless you want to duplicate the mechanism between the frame.

If you take a trip to the B&O RR Museum in Baltimore, you can get your hands on old #1, which is a 4-6-0 that everyone can climb on and play with. Its Johnson Bar works (still) so I would to show people how to drive a steam engine on the loco. Anyone wanting to know how the valve gear worked just has to look at what is going on between the frames when you move the lever.

Devon - a simpler option (as I know you aren’t that close to Baltimore) is to find some photos of Accucraft or Aster live steam locomotives. They have ‘simplified’ Stephensons. There are lots of photos around on various threads of C-16 and C-19 locos.

#5

Devon, there is a Union Pacific Pacific at the Spokane County Fairgrounds that you can get up close and personal to. I suppose that as long as you don’t try to climb into the cab, up stand on top of the boiler, no one is going to say much, as long as you act as if you belong there. Its owned by the local RR Historical Society.

If you want to ask permission, rather than forgiveness, check with Chuck, or John at Sunset Junction for a contact.

#6

Steve Featherkile said:

Devon, there is a Union Pacific Pacific at the Spokane County Fairgrounds that you can get up close and personal to. I suppose that as long as you don’t try to climb into the cab, up stand on top of the boiler, no one is going to say much, as long as you act as if you belong there. Its owned by the local RR Historical Society.

If you want to ask permission, rather than forgiveness, check with Chuck, or John at Sunset Junction for a contact.

Is it still at the Fairgrounds. I thought they moved. I will have to go check it out. I am a visual guy. There used to be an older loco at Potlatch Id do you know it it is still there. I even thought about calling out to silverwood and see If they would let me look at theirs.

#7

The loco in Potlatch is still on display. Road trip!

#8

Hey Devon, Here is a very nice look at an accurate Stephenson on this mans model. He even reverses it half way through.

Link since I can’t get the embed to work right now.

http://youtu.be/vYLooaqocmM

#9

[youtube]http://youtu.be/vYLooaqocmM[/youtube]

#10

Thank you Randy (and Joe for putting it on the forum directly) for that. I didn’t find that when I looked and that was exactly what I needed. I can now model the majority of it to a reasonable level. that is a great view of a simple version which I am sure my loco had.

#11

#12

David Russell said:

Wha’d’ja do now, Rooster?