Looking at your picture, it is not those couplers. I made a list of the cars involved and posted them.
Perhaps it will help if I took pictures of the cars and couplers and posted them.
The ones with the flanged axles (like the modern box cars) that seem to roll forever, there are no problems.
The Operating Barrel Cars of the post-Kugn era have the same couplers as the operating milk cars - they don’t have problems. It sounds as if the pin is out of alignment, or the car is too heavy to run an entire consist of operating milk cars. The 3472/3482 pre-1955 versions are smaller, but heavier-and have the better couplers that gave no problems…and they are not the coil-type either. I think those coil couplers were dropped after 1950.
Hope that helps. Tell me what you think of the idea of pictures of the cars.
The 6-19802 Carnation, from external appearances, looks to be PT-1 style, with shoes (no roller).
The 6-19894 Hoods appears to be same.
The 6-26863 American Rail Express Milk Car ,looks same.
The 6-37011 B&M appears the same, from a photo on the Lionel website.
That means, either the flat spring inside the base that pulls the armature up is weak, or the vertical pin is bent.
If you try to bend the pin, you in most all probability will either break it off or knock it loose.
Check for flat spring by comparing downforce needed on a troublesome truck to a known good one. If the spring tension is about the same, it isn’t the spring. If the pin is not vertical, no amount of spring pressure that would still allow uncoupling would hold it shut.
You understand what I’m talking about with the vertical pin, right?
The service and parts diagram for the 6-19802 Carnation car is here. The trucks, couplers and armature are identical to the post-war issue parts, have the same part numbers, and the armature is made of sheet steel. Parts diagrams are not available for the other milk cars, but it seems from your posts that they have identical couplers and armatures. You may need to take the base plate off the wheelset and peen over the shank end of the armature rivet a bit more, while backing up the rivet head. This will deflect the flat spring more, giving it more tension and keeping the coupler from opening randomly. As stated before, also make sure the coupler itself is parallel to the track and at the same height as couplers on other cars. If the armature pin is not perpendicular to the armature plate, do NOT bend the pin; bend the front of the armature in front of the pin. When properly adjusted, maintained and installed, the coupler mechanism will work properly and have few, if any, issues. The only maintenance is the replacement of weak flat springs that cause random openings of the coupler.
Yes, after reading the reply several times, I have the picture of the spring and comparing the bad one to a known good one.
Yes, I think I understand about the vertical pin - it must be straight up and down, correct? If is isn’t, it won’t work.
Larry, I have checked the springs, and they seem fine. One of the cars that was giving trouble, the 2006 Railway Express Agency Operating Milk Car, I have check the springs, closed the tab, and cannot open the tab myself by pulling on it. It appears shut tight. I don’t think the locomotive drawbar pull is as strong as my hand trying to force it open.
Again, I really thank everyone for their input. It is nice to know that there are members who are willing to help, offer advice and try and figure out the problem, so one is alone in it! I have a consist of 12 cars, including a few operating milk cars - no problems!
It’s tension and vibration. You can pull all day long in a static environment, but add the vibration of a dynamic environment and the pin will move.
Re-peening the rivet on the flat spring will do no good other than smash the rivet over and jam the mechanism. Had a bunch through here last year someone had tried that.
If the spring in bent, you can re-form it in place with a pair of hemostats. But I think we have determined the spring is okay.
Vertical OR leaning back towards the car body a tad is what you need. If the pin is loose in the armature (moving lower plate) report back here.
i think i found the solution. the 36621 milk car is slighly higher than all other cars. in a turn the tab turns slighly and pushes the tab down, opening the coupler. i bent the tab slighly down so the car behind it or in front of it won’t hit the tab. No more uncoupling!!!
One other use for the black rubber bands: Twist one around the shank of one coupler, then loop the other end around the shank of the other coupler. This way, even if the couplers open, the rubber band will keep the cars together. Very handy for shows, when you really don’t want break-in-twos… -MMM-