Hi Guys
I have a problem with some cars that kinda lurch forward and back when going down and up a grade, is there something that I can do to my cars to stop them from doing this?
Thanks
Jeremy
Using the wrong couplers; where they go around the pin in the draft box- if the shank is too big- will cause this.
Other than that, going downhill, there will be a slight give within the couplers themselves. This would be normal.
Is this HO or N Scale?
Another thing that can cause the problem is the grade its self is far to steep and causes the problem as well as the motive power gears is lurching causing the cars to lurch.
It almost sounds like you’re talking about normal slack action. This happens on the real railroads, too. But as others have mentioned above, if the loco is lurching, or your grades are too steep, they can make the problem worse. Another thing that can cause more headaches like this is a constantly changing grade. Real railroads don’t follow a “roller coaster” profile, at least not intentionally, because of problems like this.
Sounds like normal slack action. Model slack can be more severe then prototype slack, because model have no brakes or cushioning devices to regulate the slack.
You could also excessive play in your draft gear (couplers) the hole in the coupler drawbar, should fit the stud in the coupler box snuggly. You may need to add a bushing to take the play out. This is a common problem when adding Kadees to Bowser cars (which now include the required bushing).
Nick
JeremyB:
You may also want to check your engines, depending make or brand, sometimes gear ratios are different and this will cause this motion on grades. For example Bachman tends to do this going down hill, the same with Athearn. Where as Kato, Atlas and the higher end market engines tend not to do this.
Sometimes just run the engine alone down the grade and see if the engine shutters going down the hill. Sometimes if it is a mismatch in makes you will see this jerking motion going down the grade.
If you put a cheaper locomotive in front it tends to creat a lag, you may have the change positions of the engine or don’t run them together at all.
There is the possibility of coupler lag as in the prototypes, but it wouldn’t surprise me if it isn’t engine lag.
Yard Master
WTRR
My suspicion is that Robert is correctly pointing towards the source of the problem - your locomotives. Try running them by themselves up and down the grade. The most common cause of a locomotive lurching on a grade is excessive longitudinal play on the worm shaft (the shaft with the spiral gear on it). As the locomotive is starting to move forward, the shaft moves to the forward end of its play, causing some gear binding. As the wheels start turning, the worm gear moves back to its normal position. The opposite happens going downhill - the wheels try to outrun the motor, pulling the worm forward, there is a bind while the motor catches up, then the cycle starts over. Things are made worse by a train pushing the locomotive downhill. This used to be called “bucking” and was fairly common in less expensive locomotives.
Cure is to install shim washers to limit shaft play to the very minimum.
Another possible cause is wheels that wobble or are out of round on your cars. If the locomotives run fine by themselves, try leaving out suspicious cars and see if the lurching is resolved. If it is, you know which cars have problem wheels or trucks.
my thoughts, your choices
Fred W
Even though I fine tune my engines and rolling stock the last few cars on the train can still lurch somewhat. A solution that worked for me is to take a piece of a KD coupler spring and put it on one or two of the caboose’s wheels. Place the spring on the axle needle point where it fits into the truck journal. This will put just enough drag to keep the train stretched on level or semi-level track.