Dump wagon derailing

[HobbitFertang]

Hi Folks,

Think I'm getting to the bottom of this problem. The derail locations all seem to have had a 'twist' in the track (one rail lower than that opposite followed by that rail now higher than the other . . . if you get my meaning). Once I'd fixed these with DIY plastic spacers, the dump wagon ran on them fine without derailing. What was happening was that the track twist was allowing the wagon body to 'rock' and the leading wheel on the leading bogie to lift clear of the rail on one side . . and voila derailment. Generally the dump wagon runs better if it's hooked up to a loco or other wagons. I still think the fact that the RhB passenger coach had no problems with the twisted track, as it was before I fixed it, suggests its long wheelbase has some beneficial accommodating effect.

 

[Rhinochugger]

Bogie stuff is usually more forgiving of rough track for obvious reasons. Some LGB bogies have the facility to flex within the wheelbase in that the sideframes have a small amount of pivot movement on the end of the bolster.

 

[HobbitFertang]

Yes, both the dump wagon and the passenger coach have similar amounts of sideframe pivot built into each bogie, but on opposite sides front and back . . . By 'wheelbase' I mean the gap between bogies. Is that your understanding?

 

[Rhinochugger]

Yes, both the dump wagon and the passenger coach have similar amounts of sideframe pivot built into each bogie, but on opposite sides front and back . . . By 'wheelbase' I mean the gap between bogies. Is that your understanding?

No, I was thinking of the actual bogie sideframe. Certainly the arch bar trucks that I bought (and I think still have) allow the bogie side frame to pivot on the end of the bolster.

If you imagine the bogie to be a four wheel truck in its own right, then there is a small element of compensation across the four wheels of the bogie, adding yet more flexibility on uneven track.

I don't know whether the dump wagons have this feature on the bogie - it might help.

 

[JimmyB]

You're right, it does rock particularly on curved gradients. I've got some bits of lead to fix underneath . . . but the track geometry is also an issue, I fear.

I did mention this here:

One of my larger wheel base wagon derails, I have found this to be because the track, a curve on a gradient, is the issue, but due to the geometry cannot be rectified with out changing the layout. My wagon derails because of the lack of side play in the bogie, meaning on wheel (on the outside track) rises above track height, and derails.

I have done minor adjust ments to the track, but four corners will never all touch the track any the curve, you just need to even it out, and have more lateral movement on the bogies.

 

[dunnyrail]

Yes, both the dump wagon and the passenger coach have similar amounts of sideframe pivot built into each bogie, but on opposite sides front and back . . . By 'wheelbase' I mean the gap between bogies. Is that your understanding?

Sorry - I feel that I must be a little pedantic, this is actually a Hopper Wagon where loads are dropped out of a stable wagon with chutes either below or to the sides. Dump trucks generally tip the body to the side as in the example.
Though many get the Railway terminology out of kilter, particularly since privatisation where much knowledge has been lost.

 

[Software Tools]

Certainly the arch bar trucks that I bought (and I think still have) allow the bogie side frame to pivot on the end of the bolster.

With LGB bogies there is usually a little play on one side and no play on the opposite side. This gives some play at each end of the vehicle on opposite sides. It's a trade off between "trackability and "stability".