crank pin problem

ModelRailroadForums.com is a free Model Railroad Discussion Forum and photo gallery. We cover all scales and sizes of model railroads. Whether you're a master model railroader or just getting started, you'll find something of interest here.


willb

New Member
i have an ho scale sugar pine lumber 2-10-2t. when i run it in reverse there is no problem. when i run it forward, the crank pin on the right side will back out of the drive wheel. should i use something like loctite or super glue inside the driver to keep the crank pin from backing out? what i am considering doing is placing a small drop inside the hole and then threading the crank pin into it to avoid getting any adhesive on the side rods/valve gear.
 

willb

New Member
i will try and get some photos of the locomotive tomorrow. i did locate an image of a locomotive with similar valve gear at http://www.bachmanntrains.com/home-usa/catalog/?function=detail&id=113

the crank pin connects the piston rod, valve gear, and side rods at the third driving wheel as on the consolidation. the pin is a cylindrical rod with screw threads on the end that goes into the driver. i believe that there may be some binding in the valve gear motion that causes the pin to back out when the locomotive goes forward, but i can not find anything that is causing it. everything seems to move freely when i have disconnected the valve gear from the piston and side rods.
 
I Had a similar problem with a brass consolidation. One of the things that made mine do that was the Driving rods were slightly bowed inward, just from everyday handling, unforuntately. this created friction which caused that crankpin to loosen. If yours are bowed too, bend them gently outward with a LARGE flathead screwdriver blade. If that isn't the problem, hopefully the photos will help.
 

Selector

Well-Known Member
Will, when the drivers are in motion to permit the loco to move forward, and if the crank pin were kept from rotating with the driver, then the relative effect is that the gripped crank pin is being forced to back itself out since it is spinning counter clockwise relative to the rotation of the drivers. This, to me, can only mean that something else contacting the pin is acting like a vise and preventing it from rotating forward. The only thing it could be is something surrounding the outer head, and that would have to be one of the rods. It will be difficult to discern which it is, but if you invert the locomotive completely, and have a good look at the parallel arrangement of all the rods, you may find what the gentleman above suggests is the case...a rod, or rods, sufficiently bent that they actually make contact. Another possibility is that there is an accumulation of grime, semi-dried or waxy oil, and very probably some wound pet hairs, human hairs, fibres from clothing and bedding, you name it....laundry lint, perhaps. All that stuff could eventually form a credible bond, and not a lubricating medium, for any one or all pivoting rod heads.

Really good light, a magnifyer (about 6-10 times) and tooth picks, the ones with two pointy ends, would be your first method of attack. Once you have them cleaned, do the others, and those on the other side. Lube them with ATF (Dexron II or III) lightly, and you will have your locomotive back...I hope and expect. Might be a good time to do the whole shebang...motor bushings or bearings if they can be cleaned, and do the transmission.

-Crandell
 
Last edited by a moderator:

willb

New Member
guys, thanks for the information and advice. i have had the engine in storage for a long time and had only tested it prior to putting it in storage. i had not run it any great distance at that time, so i had not found the problem prior to taking it out of storage. i have checked the clearance for rods on the crank pin and they move easily. the valve motion on the right does not seem as flexible as the left. i will be checking it and lubricating everything.
 




Affiliate Disclosure: We may receive a commision from some of the links and ads shown on this website (Learn More Here)


ModelRailroadForums.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to amazon.com

RailroadBookstore.com - An online railroad bookstore featuring a curated selection of new and used railroad books. Railroad pictorials, railroad history, steam locomotives, passenger trains, modern railroading. Hundreds of titles available, most at discount prices! We also have a video and children's book section.

ModelRailroadBookstore.com - An online model railroad bookstore featuring a curated selection of new and used books. Layout design, track plans, scenery and structure building, wiring, DCC, Tinplate, Toy Trains, Price Guides and more.

Top