Atlas Model Railroad Co. - Changing siderod location on LL 2-8-8-2
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 Changing siderod location on LL 2-8-8-2
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Author Previous Topic: cp rail sd40-2 #6017 Topic Next Topic: Tiny Tot Gearmotor debut! - new pricing  

David Leonard

Posted - 2008 August 20 :  6:49:19 PM  Show Profile
I recall that this is not difficult, but I don't want to mess up. I want to alter the siderod movement so that on one engine the rods are up when the others are down. I like the alternating "pumping" action of a Mallet.

I know I have to remove the cover plate from one engine (set of drivers) and fiddle somehow with it. What fiddling do I do? Thanks!

or (David)

Country: USA | Posts: 3462

skipgear

Posted - 2008 August 20 :  9:05:09 PM  Show Profile
David,
It shouldn't be too hard, there is only one geared driver in each engine. You don't need to worry about gear/siderod timing. Just remove the coverplate, lift the geared driver so it does not mesh with the idler gear and then rotate a quarter turn or so. Reinstall the plate and screws then test.


Tony H


http://www.trainboard.com/railimages/showgallery.php/ppuser/4676/cat/500

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dave1905

Posted - 2008 August 20 :  10:13:21 PM  Show Profile
The side rods on an engine are 90 degrees apart, not 180 degrees.

If the side rods have pins into the driver then you will have to do more than rotate the driver with the gear (actually the gear has nothing to do with it). You will have to remove at least one if not both siderods, then take each driver and rotate the wheel on the same side the exact amount you want, then reattach the siderod(s). If you do not get them all the same amount of rotation they will bind and the locomotive will not run.

Dave H.



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nkalanaga

Posted - 2008 August 21 :  12:21:27 AM  Show Profile
I don't think that is needed here. What he wants to do is rotate the drivers on one of the two engines, not change the siderod positions on the drivers themselves. Skipgear's method will work fine, as all that is needed is to disengage the geared driver from the worm so those drivers can "roll" while the other engine is stationary. He won't be changing the quartering any.



N. Kalanaga
Be well.

Country: USA | Posts: 4452 Go to Top of Page

David Leonard

Posted - 2008 August 21 :  09:42:53 AM  Show Profile
Thanks, everyone! I can report success. The only problem was that I forgot to note how the trailing truck and spring were positioned before I took off the cover plate, but I figured it out and all's well. Now all I need to do is put a keystone number plate on the smokebox.

Tender electrical pickup would be nice too (I think the new run of these will have it) but I don't run late 40's era that much, so I'm satisfied for now.



or (David)

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inkaneer

Posted - 2008 August 21 :  1:35:50 PM  Show Profile
quote:
Originally posted by dave1905

The side rods on an engine are 90 degrees apart, not 180 degrees.

If the side rods have pins into the driver then you will have to do more than rotate the driver with the gear (actually the gear has nothing to do with it). You will have to remove at least one if not both siderods, then take each driver and rotate the wheel on the same side the exact amount you want, then reattach the siderod(s). If you do not get them all the same amount of rotation they will bind and the locomotive will not run.

Dave H.



I do not think so. The locomotive is an 2-8-8-2, a Mallet. It has two separate engines under one boiler. While the left and right main cranks and rods of each engine are 90 degrees apart the rods on both engines could be 180 degrees apart or they can be the same or anywhere in between. The two engines were separate not synchronized except for exhaust steam from the high pressure cylinders was then injected into the low pressure cylinders. But it was possible to slip one engine.



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nkalanaga

Posted - 2008 August 22 :  12:34:47 AM  Show Profile
Ahhhh! Thank you! I knew that "simple articulateds" could slip one engine, but didn't know if true Mallets would stay synchronized or not.

N. Kalanaga
Be well.

Country: USA | Posts: 4452 Go to Top of Page

dave1905

Posted - 2008 August 23 :  12:56:25 AM  Show Profile
I guess I misunderstood the question since on the prototype there is no connection between the two engines so one minute they could be in sync and a minute later be exactly opposite. On a model the two engines are probably geared together so however you put them is how they will stay.

Dave H.



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David Leonard

Posted - 2008 August 23 :  07:39:43 AM  Show Profile
I didn't put my question very well. I should have asked about rotating the whole set of drivers independently of the other set. "Location" is not the right word. On the prototype, the engines are in synch only when neither is slipping. Synchronization does not depend on the relative position of the siderods. On the model however, they are always in synch because they are geared together, and again the relative position of the siderods has nothing to do with it. It has to do with synchronization of rotation.


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