So the DC to AC thread got me thinking.
I know when CSX(I think) rebuilt a bunch of their SD40s they put new cabs on that were NOT stock that were supposed to be more crash worthy than the original EMDs. And of course sometimes the metal is just beyond salvage, but in the general sense it seems that all the big rebuild programs are seeing complete cab replacements. Why is that?
What is the purpose of replacing the cab on those Dash 9 to ACs for instance?
Can't you just pull out the desk, sandblast everything and put a control stand in?
I've heard in some cases there is additional reinforcement in the nose. is that the case? it's just easier to swap the cab than it is to get in with a welder and upgrade bracing?
It all just seems like added cost to little benefit from this ignorant foamer.
I could see it if say non-isolated thunder cab EMDs came in and they got Isolated cabs or something like that, but my gut feeling is that sheet metal is sheet metal.
Or could you pull the cab off, put a new one on and rebuild the original cab for the next unit.
Fair question. Crashworthiness is a factor. But also keep this in mind: I was assigned to a shop to integrate new locomotives into a fleet. Whilst I was there the management was junking all manner of test and machining tools. The mindset: replace not repair components. So what's the expense of stripping out a cab (pipefitter and electrician), sandblasting the rust (body), patching the holes (tin-knocker), prep and paint (body), install not the stuff taken out but new stuff including PTC (pipefitter and electrician) OR cut off the cab and install a new one.
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I was under the impression that fitting new modern cab gives a locomotive a complete module fitted with all current and available components .
It could start with cab isolation and include all modern equipment ie brake controllers and all forms of electronics . This removes the need to retro fit anything and everything should be available from parts suppliers .
I'm not sure if it's well known but all kinds of parts from the Dash 9 era are no longer available and second hand bits are drying up fast .
Over here there is a smallish fleet of units are being sidelined because they are SD60DC based with 30CDW brakes and it's not thought to be cost effective to update them with electronic air brakes and ECP . More current ACs do the job as well or better and have all the currently required fruit .
BDAI was under the impression that fitting new modern cab gives a locomotive a complete module fitted with all current and available components.
It still feels like the rebuilder could take in the old cabs and rebuild them in many cases.
For spartan cabs, it's not as if those cabinets haven't been rebuilt before. pre-dash2 units to dash 2 standards, then to computer controlled. Upgraded brakes and control features.
YoHo1975It still feels like the rebuilder could take in the old cabs and rebuild them in many cases.
I'd wager msot of those cabs are in worse shape than you think.
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zugmannI'd wager msot of those cabs are in worse shape than you think.
nevermind.
I would think that it would be less expensive in the long run to just scrap the old cabs and replace all of them with a standardized design and layout. The operating crews would know where everything is located which would make their job a bit easier and shop crews would know where all the parts are located, lessening down time.
It took over 30 years after the first GP7 was built for 1st generation Geeps to start getting new cabs, over 10 years after rebuild programs were born for them. I wonder if what appears to be serviceable cabs that are still fine are getting dumped not because they're basket cases, but because of the fear that they might start showing their age in 5-10 years on locomotives that I assume they're aiming for at least 20 more years of service out of at a minimum?
Edit: Forgot about Santa Fe's Topeka cabs, but it seems like the end of the 70's is when other roads started doing more than just chop nosing the short hood when a 1st gen Geep was rebuilt.
Leo_Ames It took over 30 years after the first GP7 was built for 1st generation Geeps to start getting new cabs, over 10 years after rebuild programs were born for them. I wonder if what appears to be serviceable cabs that are still fine are getting dumped not because they're basket cases, but because of the fear that they might start showing their age in 5-10 years on locomotives that I assume they're aiming for at least 20 more years of service out of at a minimum? Edit: Forgot about Santa Fe's Topeka cabs, but it seems like the end of the 70's is when other roads started doing more than just chop nosing the short hood when a 1st gen Geep was rebuilt.
The Topeka cabs at least undeniably show some advantage.
These cabs are just plate steel. Any welder worth his union card should be able to fix anything wrong with them Oh, is this mount for the desktop in the way of the placement of the traditional control stand, let me fix that for you.
Like I said, I can see pulling cabs off, refurbishing them elsewhere and then in the meantime one already done is installed, but buying new steel, even if recylced and starting from scratch just seems odd on the face of it.
If nothing else, you're subject to the fluctuation of the price of steel whereas an existing cab, the Steel's been paid for already.
Keep in mind....steel bends and twists. After many years of service, nothing is going to be as straight and true as it was when it was new. That makes retrofitting and rebuilding a much more onerous process. Simply starting from a brand new cab, would simplify and speed things up. Time is money, and having to strip and rebuild something to as new condition and current standards takes a bit more time, money and effort than I think you realize.
YoHo1975... If nothing else, you're subject to the fluctuation of the price of steel whereas an existing cab, the Steel's been paid for already.
And the depreciation has already been applied to the books.
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I would add that everything ahead of the alternator is getting replaced on a Dash-9 (or AC4400) to AC44C6M rebuild. Ergo, replacing all of this as a unit probably makes more sense modification wise.
Greasemonkey Keep in mind....steel bends and twists. After many years of service, nothing is going to be as straight and true as it was when it was new. That makes retrofitting and rebuilding a much more onerous process. Simply starting from a brand new cab, would simplify and speed things up. Time is money, and having to strip and rebuild something to as new condition and current standards takes a bit more time, money and effort than I think you realize.
But retrofitting and rebuilding cabs used to be the norm. And I would think that steel fatigue would only have been worse in those units.
D.Carleton I would add that everything ahead of the alternator is getting replaced on a Dash-9 (or AC4400) to AC44C6M rebuild. Ergo, replacing all of this as a unit probably makes more sense modification wise.
But the Cabs aren't part of a "unit" in this case, they are bolted on Separately .
Anyway, I feel like I'm just arguing against everyone now. While I think it is entirely possible that the railroads/builders DO NOT have particularly good reasons to do what they do every time.
I'm also not trying to suggest they MUST be doing something wrong. There's just something in this process that elludes me.
Like, maybe there's an OpEx vs. CapEx style of difference here where it's not cheaper to buy a new cab, but the accounting makes it easier.
The kind of answer that anyone in a buisness that makes things gets, but the Engineers really dislike.
YoHo1975Anyway, I feel like I'm just arguing against everyone now.
YoHo1975 But retrofitting and rebuilding cabs used to be the norm. And I would think that steel fatigue would only have been worse in those units.
Possibly, but labour costs have gone up considerably over time.
Greasemonkey YoHo1975 But retrofitting and rebuilding cabs used to be the norm. And I would think that steel fatigue would only have been worse in those units. Possibly, but labour costs have gone up considerably over time.
Fully expect the tax aspects of the 'rebuild' are guiding what parts are reused and what parts aren't.
Back in the steam days, in many cases, the only thing that was actually 'rebuilt' was the engine number - everything else was hardware that was new to the engine number.
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