After some research, I found that one of the main reasons that single axle trucks bear a greater impact at rail joints than two axle trucks is the rail compression factor. As the wheel passes over a rail, it presses down on it, and as the joint is approached the next rail section will be slightly higher than the occupied rail, thus there is a THUMP when the joint is crossed over. One way to ameliorate this affect for single axle trucks is to use larger diameter wheels, which will “soften” the angle of the wheel/joint contact. The TTOX used 28" wheels, so if those were replaced with 38" wheels, this affect would be lessened. The question is if it would be enough to make a significant difference.
The real killer was getting squeezed off the rails when there was high trailing tonnage. Even with added weight, it would remain a problem because of the geometry. Intermodal train tonnage is much higher now than in the late 70s when these cars appeared, so that makes the problem worse.
Has anyone seen any of the other classes of 2 axle spine cars. The TTX website shows only the TTOX class, but I thought there were others. I haven’t seen one in about 5 years now. I thought they had all been removed from service. I had thought about posting a have you seen any of these cars post earlier but this seem as good a place as any to ask!
Keep in mind the larger wheels will add weight and raise the centre of gravity. If the track was smooth enough the 2 axle car would be ok, but the whole idea of trucks is that you can use rougher track and still get a good ride. What would be the point in adjusting all of the track at huge expence just to be able to run a few long wheelbase two axle cars that may be marginaly cheaper to build or have less weight?
I do know that in Germany they use two axle cars for freight at 160 to 200 km/h trains but the main track is ultra smooth and yet in yard track and sidings these cars have a bumpy ride, but not an unstable ride because the joints are across from each other. In the US the joints are staggered wich gives a smoother ride for cars on trucks but gives an unstable ride for two axle cars. There is still more bolted rail main line around than you would think.
Have you seen in Germany they use 4 axle trucks (8 axles per car) with 8’ wheeels and very low deck height? Again these cars demand very smooth track and even most other European countries can not use this design.
I suspect with scrap steel prices as high as they are, they’ve been or will soon be sent to the srapper.
I don’t know of any other two axle cars in the TTX fleet. The TTOX came in two “flavors”: The single unit and a drawbar connected “four pack”. The only other possible single axle railcar in U.S. freight service today would be the Trough Train (which has single axle trucks on the end units), but I don’t know if the Trough Train is currently running anywhere. BTW, the wheel size on the single axle portion of the Trough Train is 38".
(1) I do not EVER AGAIN want to deal with these things again in a yard. These suckers (single bogie trucks) are hands-down the worst switch pickers, mechanical switchman and flopover switch hoppers ever seen. They also do strange things around frog guard rails. Any savings generated by the single axle is not given to the track department to pay for the corresponding increase in damages to switch points and switch OTM usually caused by bare table TTOX cars.
(2) Increase tonnage on these things and they aught to be banned from anyplace with jointed rail. Wheel size is NOT going to mitigate the issues of impact damage at a single point. Joint end batter would only rise because of fewer but bigger impact hits.
(3) The concept of steerable/ torsion sprung trucks causes me concern. AAR/TTC in Pueblo ought to be looking at what this does in terms of rail climbing in curves, not on the high rail, but on the low rail with the angle of attack changed. The F.A.S.T. track in Pueblo has done some evaluation work on these cars, but I never heard the outcome.
Agree with Eric/Kenneo that these cars can be a menace in the US…If they do make a comeback, I hope some serious “real world” testing is done prior to introduction into the rail fleet. Really do not want another episode similar to what happened with center plate lubrication on double-stack well cars shortly after their placement into heavy use.
I agree that there would need to be sufficient testing before a prospective modified (read: “upgraded”) version of TTOX ever surfaces. But it sounds like the clinical testing done at Pueblo doesn’t always account for real world experiences with new innovations.
From a rail joint damage perspective, how is it that wheels on single axle trucks would cause more joint damage than a similar size wheel on a two axle truck?
BTW, what was the problem with the centerplate lubrication on the double stack well cars to which mudchicken refers?