Extracting this post from the DC-DCC thread, it deserves its' own thread.
Overmod<<Today's freight cars that have rotating roller bearings are anything but free rolling.>> It is long past time for someone to extend the current discussion on truck physics and truck-tuning 'best practices' to cars with rotating endcaps. Here are a few initial thoughts for whoever does that. The ones I'm familiar with have coned axle ends, with a wirelike thin extension through the sideframe on which the little cap is pressed. Under ideal construction conditions, this should have the same guiding and location characteristics as the double-cone pointed-axle construction, with a slightly larger effective contact patch just inboard of where the wire end commences. This immediately implies that the truck-fram alignment and spacing would have be be highly precise, as there is less freedom for the wheelset to move side-to-side within the constraint of the larger-angle coned recess for accommodation. It also implies that slightly greater clearance at and through the sideframe for the 'wire end' needs to be provided, for the cones to do their work effectively, and that the caps be carried slightly outboard of the truck frames when pressed on -- perhaps with a guide tool similar to that for Bowser valve gear to get the spacing correct without trial and error fiddling. If you used a truck tuner to machine the active part of the cones in the sideframes, it might be necessary to fine-adjust the sideframe lateral spacing to the new profile. I am not sure a typical gauge for this would be inexpensive to make. Now, on the other hand, anyone over the age of about 50 will be familiar with the operating principle of Hot Wheels cars, which involves a Delrin/acetal bushing pressed into the wheel bearing on a thin wire axle. It would certainly follow that if the sideframes were tooled or machined to insert a thin-contact version of this type of bearing, if not indeed made of the appropriate material with the appropriate bearing section, you'd get at least comparable rolling resistance with the cones then providing only lateral compliance. (Yes, you could use watch-style hole jewels for this purpose, if you have the special knowledge or experience, access to materials and equipment, and weird predilection for overkill that go with that...) (I believe the counterpart for Delrin coned bearing surface bushings is already manufactured and sold, along with appropriate tools and instructions to cut older sideframes to install and align them.)
It is long past time for someone to extend the current discussion on truck physics and truck-tuning 'best practices' to cars with rotating endcaps. Here are a few initial thoughts for whoever does that.
The ones I'm familiar with have coned axle ends, with a wirelike thin extension through the sideframe on which the little cap is pressed.
Under ideal construction conditions, this should have the same guiding and location characteristics as the double-cone pointed-axle construction, with a slightly larger effective contact patch just inboard of where the wire end commences. This immediately implies that the truck-fram alignment and spacing would have be be highly precise, as there is less freedom for the wheelset to move side-to-side within the constraint of the larger-angle coned recess for accommodation. It also implies that slightly greater clearance at and through the sideframe for the 'wire end' needs to be provided, for the cones to do their work effectively, and that the caps be carried slightly outboard of the truck frames when pressed on -- perhaps with a guide tool similar to that for Bowser valve gear to get the spacing correct without trial and error fiddling.
If you used a truck tuner to machine the active part of the cones in the sideframes, it might be necessary to fine-adjust the sideframe lateral spacing to the new profile. I am not sure a typical gauge for this would be inexpensive to make.
Now, on the other hand, anyone over the age of about 50 will be familiar with the operating principle of Hot Wheels cars, which involves a Delrin/acetal bushing pressed into the wheel bearing on a thin wire axle. It would certainly follow that if the sideframes were tooled or machined to insert a thin-contact version of this type of bearing, if not indeed made of the appropriate material with the appropriate bearing section, you'd get at least comparable rolling resistance with the cones then providing only lateral compliance. (Yes, you could use watch-style hole jewels for this purpose, if you have the special knowledge or experience, access to materials and equipment, and weird predilection for overkill that go with that...)
(I believe the counterpart for Delrin coned bearing surface bushings is already manufactured and sold, along with appropriate tools and instructions to cut older sideframes to install and align them.)
All my rolling stock is old stock. I've only seen videos of rotating end caps. How are they held on? I've seen that models with these come with extra end caps. If one falls off, what happens to the rolling quality of the car?
Henry
COB Potomac & Northern
Shenandoah Valley
Rotating end caps are generally pressed on with a friction fit. They might be glued on some examples. I'm more of a friction bearing modeler, so I don't have tons of experience with roller bearing freight car trucks.
That being said, Kato rotating end cap trucks are some of the best free-rolling trucks I've ever used. They are that good. However, not all trucks roll like Katos. The old Athearn ones from the 1960s were terrible, for example. But generally speaking, the bearing end cap's presence has little to do with the rolling quality of the truck. It's just an add-on part along for the ride. The actual bearing surface is the axle and the truck journal.
One thing not mentioned so far is that there needs to be more clearance between the bearing cap and the truck journal than normal so that the bearing will rotate freely. This is a compromise in appearance, but many modelers care more about the spinning end cap than the extra space around it.
Which I find interesting, they will settle for out of scale rotating end caps but not oversized wheels and couplers that work better?
Like you Paul, I model a time when only one prototype had rotating roller bearing trucks that I am aware of - The new Beth Steel 75' piggyback flats.
I will settle for caps that don't rotate, mine all have Kadee sprung trucks with Intermoutain wheelsets.
I do have a variety of freight cars with closed Timken roller bearing trucks that were starting to be more common in my era.
I will now leave this descussion to those who model more modern equipment.
Sheldon
Oh, I forgot about those tiny rotating bearing end caps on my rolling stock. I had to go look to see which cars had them on and to see which cars may be missing one or two. Athearn Genesis, Tangent and Scale Trains are at least three of the manufacturers that I have found so far.
Paul3 Kato rotating end cap trucks are some of the best free-rolling trucks I've ever used. They are that good. However, not all trucks roll like Katos.
When I first switched to HO the Stratton And Gillette was set in 1968. I had several freight cars equipped with Kato roller bearing trucks with rotating end caps.
I completely agree. These were some of the most freely rolling trucks I have used.
-Kevin
Living the dream.
Most of the time the caps coming off is not an issue for me. Sometimes on a brand new car one will be loose. If the truck is removed they are fairly easily reinstalled and I just press them on hard. They also come with extras in a bag.
We have plenty of freight cars with the rotating caps and they get handled a lot because my son is constantly changing out my modern era freight cars for his and vice versa. This is handling cars sometimes daily. This is also why I have tried to go as modern as possible--so that less stuff gets handled daily. If I can buy a 2016 or 2017 correct prototype freight car (Aurora 50' TTX and IC) I will, but there are certain colors or roadnames he prefers.
Generally the rotating bearings do slow cars down a bit but not nearly as badly as Rapido abs plastic trucks. They are significantly worse than any of the rotating bearing freight cars. I throw those trucks away and replace with Athearn when they fit as a drop in replacement (non-rotating rb replacements).
Yes a dozen rotating bearing cars can slow a loco down a bit depending upon which cars they are. That is why my son wants to run 2 or 3 units all the time which has been an epic fail in dcc as my 2 amp starter system just does not get it done for heavy trains. In plain dc we can easily put 4 units on a heavy train and could go to 70 or even 80 cars on that train on the very same track that NCE says is garbage for dcc use.
Regarding offset of rotating bearings sticking out too much? Well there are just other hills for me to die on. If they work we just use them. Mostly we are just playing...
I like the novelty of rotating bearing caps on my slow-speed switching layout. Just yesterday unboxed a couple Athearn Genesis 20K Gal GATX black band tank cars, nice models. Each car had two missing end caps loose in the packaging. Though I've lost but one cap over the years I'm glad to see Athearn now providing a couple extra caps in the box. Tangent added four spare caps with their PC G-43 Gon's 'spinning' roller bearing trucks. Have a few cars equipped with Kato's rotating caps, but don't recall if spares were provided.
Regards, Peter
HO-VeloHave a few cars equipped with Kato's rotating caps, but don't recall if spares were provided.
In the 1990s they came with a sprue of 12 caps, only eight were required. They had to be installed by the user. I usually lost one or two in the process.
In preparation for airbrush painting rotating cap trucks I remove the wheel-sets, then protect the journals and axle surfaces with a tiny dab of plastic compatible grease. After painting and weathering excess grease can be removed with a clean micro-brush.