Why no more A1A wheel arrangments?

[oltmannd]

Those equalized A1A trucks have a bazillion parts to them, and getting at the brakeshoes on the ones with the drop equalizers is a big pain.  The 4 axle Blomberg has too many parts.  The A1A has about double.

I wonder if the patterns for the EMD or AAR style A1As are even around anywhere.....

MP got the job done on 4 axles - good enough for the commuter market, anyway.

[CSSHEGEWISCH]

MPI may have had weight issues with the MPExpress suburban locomotives, but an A1A truck would have become a cost issue.  It would be a non-standard (expensive) design and would have required a totally different frame to allow for the longer wheelbase.

[YoHo1975]

Sure, but how much additional maintence do those trucks really entail? And sure, the genesis is a marvel of engineering, sure, but was it worth the cost in engineering when a more stock design riding on A1As would have been as effective? remember Amtrak's always being squeezed for money so every dime of expense is fought for. Given that Alaska got the 70 MAC with convertable trucks, it seems like it wouldn't have been an impossibility.

 

But even beyond the Genesis, what of MPI? They're having weight issues with the MPExpress. Couldn't the A1A truck have allowed them more room to play with to get a better performing engine? Why design something less optimal just to use a 4-axle truck? 

[AltonFan]

I think a combination of cost, an increase in allowable axle loads and an increase in diesel engine output all did in the A1A truck.  You don't want to have to maintain an extra pair of wheelsets if you don't have to.

Especially if that extra pair of wheelsets is just along for the ride.

[carnej1]

  Interestingly there are some modern "A1A" Passenger units in North America. The Alaska Railroad's SD70MACs have the ability to switch one of the AC Inverters from traction to HEP for passenger train service. When this feature is selected one traction motor on each truck is cut out, making them "A1A". For freight the engineer switches the electrical system back to standard CC configuration.It's a clever way to use the units electrical capacity and have plenty of "hotel power" available without needing an auxiliary genset.

[oltmannd]

I think a combination of cost, an increase in allowable axle loads and an increase in diesel engine output all did in the A1A truck.  You don't want to have to maintain an extra pair of wheelsets if you don't have to.

The Genesis design is a good example of how you can build a modern passenger locomotive with good ride quality and packaging on 4 axle trucks.

[YoHo1975]

So, with the F40 thread and the Hybrid thread and a couple other threads all talking about the weight problems with classic framed modern passenger power, I've been wondering, why was the A1A wheel arrangment dropped? Wouldn't it have been cheaper engineering to simply use A1A trucks with a proven design rather then the added cost of the AMD-103 design? Why doesn't MPI look at A1A to counteract it's wheight problems? or the F59PHI?

With A1A you could fit larger engines and HEP generators, you would have better ride characteristics, You could run on lighter track. What's the downside?

 

I mean sure the old Bloomberg A1A bogey is a little long in the tooth, but there are Still bloomberg B and Flexcoil trucks out there and I would think that bringing it into the modern world would be way lower cost then what the Genesis was.

 

 

For that matter, why wasn't A1A considered for the GP60Ms?