The discussion on ultrasonic cleaning of steam Loco trucks for a binding gear box problem has evolved to where the problem may in fact be worn gears, rather than crud.
The 3 photos below show an HO Rivarossi Cab Fwd Front Truck unit gear box assembled & then disassembled. The geared axle & the solo gear are the gears from the recalcitrant gear box.
If someone is familiar with these gear boxes, could they confirm the gears appear worn to the point where it is probable they will bind/not run freely?
Thanks
Tanked
(Please excuse carpet fiber below, didn’t notice it when taking shots)
As inexperienced as I am in such matters, my eyes suggest to me that it has had some considerable wear…or else it was poorly machined to begin with. Hopefully you can get a replacement from NWSL…although I will bow out and let others who have done this speak up. The last image, by the way, could stand an f-stop reduction or else more light, or a longer exposure so that we can see deeper into the gear and see the surfaces and edges a bit better.
The gears look fine to me. The older Rivarossi axle gears (like what you’ve got) are blackened brass, but the blackening gets worn off the contact area very quickly. The problem with these gears is they have to be adjusted just right to work smoothly. If they’re off by a little, they can run rough, or even bind a little. It can take some trial and error to get it right. Fully metal gears also need extensive break-in.
I agree w/ Darth on the gears. How did the drive perform prior to disassembly? Was it disassembled for a problem or maintanence? The burrs on the axle drive gear could have been caused by grit or filings within the case or an occasional bind/ jam in the mesh. If there is too much clearance and you have no way to close the tollerance, even replacing the gears won’t help.
You could deburr the gear very carefully with a file and/ or some 400-600# wet or dry paper. Labelle 106/ w teflon can also help smooth out the mesh.
It was being put on to a ‘from the bits bin’ Cab Fwd I was building.
I checked it & found that the gears were tight & would bind if I tried to turn the wheels over by hand.
At first I thought it was old grease etc, but stripping the gear box did not reveal that. With the valve gear disconnected it is still tight or won’t turn more than 1 rev. before binding.
Latest photos may help sort this - if gears are not stuffed, how does one ‘fine tune’ the meshing??
Be sure it is not a cracked wheel that is slipping and causing things to bind up. I have a riv 080 that has one drive wheel that is cracked and slips so it does not make it past one or 2 revs.
