A Question to Anyone that knows the Answer?

[JCRQ]

I have been pondering this for years. G.E. and E.M.D. both make Steerable/Radial trucks for their locomotives. but they only make them for their A.C. traction units and not D.C. traction units. Why is this and what makes them only usable or effective for A.C. traction equipment?

[ndbprr]

This is stricly a guess so treat it as a potential possibly very wrong answer.  I think that AC motors use the axle as the armature whereas DC motors hang on the axle and drive a gear on the armature which drives a gear on the axle. Perhaps clearances on DC motors do not allow radial trucks or complicate the drive system.

[beaulieu]

 EMD offers its Radial trucks on its DC motored locomotives. It is an extra cost option that not all railroads feel is worthwhile. All EMD SD70 series locomotive both AC and DC have Radial trucks. With the introduction of the new SD70M-2 and SD70ACe EMD introduced a new lower cost HTSC truck without radial steering. Some buyers of both models have chosen the cheaper HTSC over the superior performance, but higher cost of the HTCR truck.

Canadian Pacific found that the savings in rail wear with GE's self-steering truck were not enough to offset the higher price and higher overhaul cost, and so their newest ES44AC locomotives are equipped with GE's older Hi-Ad truck.

 

[JCRQ]

ok i didn't no about EMD i wasn't quite sure about that but, why weren't they ever offered by GE on DC models.

[wisandsouthernkid]

not true, AC traction uses a conventional motor like the DC traction does to what i understand.  The only engines that i had ever heard of using that were the Milwaukee road bipolar electrics that had the armature on the axle

[CSSHEGEWISCH]

wisandsouthernkid

not true, AC traction uses a conventional motor like the DC traction does to what i understand.  The only engines that i had ever heard of using that were the Milwaukee road bipolar electrics that had the armature on the axle

NYC's S-motors had a gearless drive with a similar arrangement.

[trainfan1221]

Weren't these kinds of trucks actually invented in days before AC? I would assume they were perfected to operate with alternating current.

[K.C.Jones]

I agree with the other replies. I don't think there is a mechanical problem with a D.C. radial truck configuration. But don't forget about pricing. If you only offer a radial truck on your D. C. locomotives, your units will cost more than your competition. This makes selling your units much more difficult.