Would anyone care to discuss the conversions that they have performed? Anybody notice a higher rate of wear in wheel tread taper or the radius leading to the flange caused by the loss of lateral motion with the roller bearings, it would seem that with a friction bearing axle the axle would be able to find its center of the track gauge with much less resistance as it would just have the lateral happening on the bearing surface, where as the roller would be moving the entire mass of the car/locomotive. How does it affect lead and trailer engine trucks when converted, I have seen arrangements on trailing trucks equipped with roller bearings that included rollers on top of the bearing boxes to allow for additional lateral. The UP RR used laminated steel and rubber under there springs to accomplish this on there centipede tenders.

Thanks for the input,
Mike Tillger

Indeed it would seem that the lateral could be allowed in additional box play, on something that has independent boxes..... Within limits of course. Using two operations as case studies that have done a great number of conversions, wheel wear only proved to be a problem if nylon wear liners were not used in the center bowls (this can of course only be utilized if the bowls are flat). To not run into wheel wear issues free truck movement is absolutely critical.
In terms of locomotives, if one looks at new specs for allowed combined lateral play and the applicable MECHANICAL DEPARTMENT condemning limits for wear (not fra, fra allows for wear to the point of causing damage to these machines) then allowing for an appropriate amount of lateral play is not terribly difficult on pilot and trailing trucks. If tram is out of whack then of course wheel wear will occur at an accelerated rate.

Cheers, Jason

I can't really speak to the friction bearings, but have extensive experience with Hyatts vs. AP rollers. We have a captive situation where equipment that doesn't leave the railroad cannot be turned. As a general rule, the Hyatts in similar service will go roughly twice as long as the APs will between turnings. I couldn't believe it at first, but went back and looked at the records and it was the case. From a locomotive perspective, it would be an AAR B truck with APs vs. and EMD GP truck with Hyatts, so not exactly apples to apples. That's what we're seeing.

ETA

I was working in the Car Department when the plain bearing to roller bearing conversion was going on with freight cars. The lack of lateral clearance in the AP bearing resulted in excess gib wear on the bolsters of the three piece trucks. Eventually the three piece truck were redesigned with about 3/8" of additional clearance between the bolster gibs.

Timken sold the AP conversion based on a reduction in journal oil usage. The down side of AP bearings is that if there is a bearing problem, most shops can rework the journal, brass and waste to get a car back on the road. The same is not true of an AP bearing. It has to be changed.

At the last ARM conference in St Louis, there was a presentation by a Timken engineer on steam locomotive conversions to tapered roller bearings. This was a very interesting presentation. It is too bad that information from this presentation has apparently never been distributed. He was there to address a conversion of a steam locomotives to tapered roller bearings that had failed. He went through the reason for the failure and concluded that steam locomotive drive wheel conversions to AP bearings was not practical. He said that there was a lot of lateral forces to be dealt with in a steam locomotive's drivers and for taper bearings to do this the clearance in the bearings on both sides of the frame has to be coordinated so both bearings share the lateral load. To do this, the locomotive frame has to be designed and machined to achieve this sharing of the loads. He did not think that conversion of locomotives not designed for tapered bearings was possible.

Can it be elaborated some of the experience found in a steam locomotive roller bearing conversion? I would think that the shoes on the driving boxes would have to be kept in a pristine condition, probably more so than most of what is practical.

As I understood the gentleman from Timken, both bearings must be mounted in a cartridge, similar to the way traction motors with roller bearings are mounted on large locomotives today. Then the cartridge is mounted in the locomotive frame. I believe his point was that the opening in the frame of locomotives using shoes and wedges was not large enough to accommodate this arrangement. There were a number of steam locomotives built with roller bearings and I assume that the locomotive cyclopedias have some details of this construction.

The issue with the AP bearings is that of the angle of the rollers, the steam era driver roller bearings had a much steeper angle than modern day stuff. This angle allowed for adequately handling the lateral loadings.
There are still steam era design bearings available from another manufacturer.....

Cheers, Jason

To further what Charlie is stating, it is interesting that most (if not all) AAR-B trucks were equipped with Timken sealed or AP bearings, I don't recall seeing a Hyatt in this application, whereas most GP/Bloomberg trucks have Hyatt (although some have AP conversions).

My curiosity is what does this bearing and wheel wear arrangement have with the equalization of the trucks - an AAR-B has double inboard and outboard equalizers, where the Bloomberg has the springs directly on top of the box.

Each arrangement would seem to be set up accordingly, and wheels would also wear accordingly - i.e. - the Hyatts would make up for the lack of lateral in the top loaded springs.

Am I looking to far into this? The discussions regarding the amount of lateral from box (sealed) roller bearings to AP class has always intrigued me...

Thanks!

MRLX1020

I was with the Santa Fe in Argentine Kansas (Kansas City) in the 70s. We were at that time the home of all the GEs on the system. This included U25Bs, U28CGs, U30CGs, U23Bs, U23Cs, U33Cs and U36Cs. The truck shop foreman had come from Barstow about a year before I was transferred there from Topeka. He had somehow gotten permission to start changing out Timken bearings on the U boats for Hyatts. There was some machining that had to be done on the trucks frames somewhere which we did locally of course, but the biggest hurdle was to get the Topeka Wheel Shop (where all our diesel wheels were mounted) to build the wheel sets. He started out with the 7900s (U28CGs) which of course had been relegated to freight service by this time. He was gradually moving through the U28s with the plan to change all of the GEs to Hyatts. I was with the Industrial Engineering group and couldn't believe that with all the other stuff that we had to do to try to keep these units running we were poring money into parts of the locomotive that actually worked like they was should; simply to try to cut down on spare parts at some time long in the future. I don't know whether his fatal illness killed the project or the ordering of the large group of 8010 Class of U30Cs but I think there were only a handful of units completed. They looked fiunny and now I wonder about wheel wear after reading these posts.

During my time with the NS Steam Dept. I designed AP roller bearing conversions to replace the old Timken bearings under the 3 axle truck water cars and the 3 axle trucks under the A & J tenders. We ran the box lateral to the prints, I think it was 3/16", the truck frames were rebuilt to the N&W and/or General Steel prints, trammed and fitted with manganese wear liners. We used standard 2 wear AP equipped wheelsets straight from the car shop. There was never a problem with wheel wear or flange cutting.

A more interesting roller bearing conversion was the replacement of the 611's big end of the main rod bearings with off the shelf Timken bearings. We also made new wrist pins and bearings.

Robert Yuill
http://www.historicmachineryservices.com

From what has been posted and what has been PMed to me, I have drawn the following conclusion, mainline operation has little or no effect on the RB conversion wheel wear with no allowance for lateral, but slower speed operation or yard operation with lots of turnouts( short S curves) wheel wear increased slightly. In my experience I have seen an increase in wear in the radius leading up to the flange and once the radius is worn down, flange wear goes up rapidly compared to coaches that retained their Friction bearings. Thanks to all who added their experiences.

Mike Tillger

While I was at the Smokys I dealt with the aftermath of many friction to roller conversions. All of the cars were roller, some AP, some not. Almost all of the coach and crown cars were old six axle heavyweights that had either been converted from frictions (or old hyatt/skf rollers) to AP rollers. Some still had the SKF bearings under them. There was a mix of old 5x9 and 5.5x10 trucks, but all the AP bearings were 5.5x10 so you had to watch what your bearing centerlines were on the wheelsets. Some of the boxes were cast adapter boxes for this very purpose, some were home made jobs. There were pros and cons to each.

The conversions worked well, save one issue. The reduction in lateral play was not in the favor for six axle cars working on a mountain railroad. The real problem was that those six axle cars didn't (and do not) belong on a railroad that is operating daily service through 43 miles of 10-15 degree curves. The loss of the lateral made it worse. In order to get enough lateral, you had issues with equalizers rubbing on the pedestals, and all the issues that arise from that. So you remove the lateral and then create high wear rates on the pedestal liners and boxes. At the same time the flange wear was incredible. No joke, I had some cars that came in for wheel replacement every 18 months because the flanges were dead. I had to renew many of the box and pedestal wear plates at the same time. Many times I half considered converting back to frictions just to get the lateral back. Really though, if I had my way we would have replace the daily runners with four axle coaches. I continued to convert some of the four axle cars to AP rollers, from Hyatt, SKF, and Timken lube bearings. Most of that was due to parts availability and to help with commonality of spares. I think I had 12 different types of wheelsets when I started there.

Bottom line, newer isn't always better. It's a matter of what works well for the environment you are in. What is more robust in one application may be a detriment in another. Interesting note that one of the posts in this thread noted rollers on a steam locomotive. I'd lay money that hey was talking about the AP rollers that were on the 1702. Same story. That is why we went back to frictions. They just work better for that application.

Feel free to back channel me if you would like to discuss more. . .

Ryan Scott

Can you get 5x9 roller bearings?
Dare I ask about 4 1/4 x 8?

Robert,
Both sizes are still listed on Timken's website as being available.
Mike Tillger

Timken bearing advertisement from 1959 about roller bearings.
http://www.youtube.com/watch?v=j5EAVKiWAqY

Somebody had a lot of imagination!

Mike Tillger