Metro begins replacing wheels on 7000 series fleet

Metro today announced that it has begun replacing the wheels on all 7000-series railcars under new, higher standards that will allow Metro to resume regular maintenance intervals and gradually add more 7K railcars to service, with the first railcars going into passenger service this morning.

Under the new process, with concurrence from the Washington Metrorail Safety Commission (WMSC), Metro will increase the fit and press tonnage used to mount the wheels to the axles on the railcar.

Due to the 7K shortage, Metro continues to utilize its oldest, least reliable railcars in the legacy fleet. As more 7000-series railcars are completed, tested, and able to run longer between inspection intervals, Metro will gradually be able to increase the number of 7Ks in service providing customers with more reliability and comfort. This will allow Metro to eventually remove the older, legacy railcar fleet placed into service.

Pressing the wheels is an exhaustive process that requires 72 hours of work for each pair of railcars. Unlike changing the tires on a car, the entire wheel assembly or truck, including the axle, frame and two wheels must be removed from the railcar, similar to removing the entire front end of a vehicle. The wheels must be disassembled from the truck, and new wheels with a tighter fit installed at an increased force onto the axle before being reassembled onto the railcar.

It will take several years to complete on all 748 railcars of the 7000 series fleet

https://www.wmata.com/about/news/Metro- ... andard.cfm

The wheels must be disassembled from the truck, and new wheels with a tighter fit installed at an increased force onto the axle before being reassembled onto the railcar.

So are they replacing all the wheels, or repressing the existing ones??

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So are they replacing all the wheels, or repressing the existing ones??

They are replacing the original equipment manufacturer wheel as the wheels must be replace after they wear down to below a defined minimum diameter. The whole process was a given and will happen several time during their service life. It is a kin to replacing worn tires on a motor vehicle.

Sand Box John wrote: ↑Tue Dec 05, 2023 7:54 pm farecard
So are they replacing all the wheels, or repressing the existing ones??

They are replacing the original equipment manufacturer wheel as the wheels must be replace after they wear down to below a defined minimum diameter. The whole process was a given and will happen several time during their service life. It is a kin to replacing worn tires on a motor vehicle.

So they're scrapping the wheels, and hopefully recycling them into much better spec wheels to be put on. Melt 'em down and redo 'em!

I don't know if RR wheels can be/are recapped as crankshafts are. (Built up with welding, then ground down to spec,)

But as discussed in the article, this is replacing ALL the wheels, worn or not.

The unaddressed question is how is it that WMATA aka us, are paying for this FUBAR, not the manufacturer.

We don't know that WMATA is paying for this, but we do know that WMATA is doing the work to fix these issues.

I'd be surprised if lawyers are not expensively negotiating the terms of the liability and that part of that is negotiating how completely that is sealed.

I'd also not be surprised that WMATA is choosing not rely on Kawasaki given that they also needed to replace the wiring on ~600 of the 7000 series cars and replace the platform safety barriers between cars with chains.

Press coverage was that WMATA was paying $$$$

The chains vs. flappers was driven by the blind community,

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I don't know if RR wheels can be/are recapped as crankshafts are. (Built up with welding, then ground down to spec,)

The only railroad wheels that I know of that typically get new tires are the driving wheels on steam locomotive. The inside diameter of the tire is typically around 6" smaller then the outside rolling diameter. The tires are shrink fitted to wheels by heating tires up by around 250° F above ambient.

But as discussed in the article, this is replacing ALL the wheels, worn or not.

The unaddressed question is how is it that WMATA aka us, are paying for this FUBAR, not the manufacturer.

Likely cheaper to swap out the not full worn wheels then spending the time and labor doing the gauge inspections followed by repressing as necessary.

extra post.

It appears that the inside diameter of the wheels has been altered in some way, probably the diameter has been reduced by some amount. But also the profile might have been changed in some way or both. Appears axels are not being changed. New wheels may be expensive and getting a supply spot may be difficult if wheel builder has a full order book?.

west point wrote: ↑Fri Dec 08, 2023 9:34 pm It appears that the inside diameter of the wheels has been altered in some way, probably the diameter has been reduced by some amount. But also the profile might have been changed in some way or both. Appears axels are not being changed. New wheels may be expensive and getting a supply spot may be difficult if wheel builder has a full order book?.

So it's possible to re-use the axels but the wheels themselves need to be recast and re-machined.

WMATA is paying for it because they expressly set the Axle criteria to the letter during rail car design. They got what they very specifically asked for. As per the recent NTSB findings, they had plenty of time while the cars were still under warranty to discuss the issue, and did nothing.

The replacement is a combination of new axle assemblies and re-pressing existing wheel sets.

Some axle assemblies were already condemned across the fleet for previous issues with the grounding brushes, and others because of service failures in the gearbox

Both issues got remedied across the fleet via field modifications, but the condemned axles do need replacement.