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Re: SP gear ratios
Author: OPRRMS
Date: 12-16-2010 - 15:55
SP5103 Wrote:
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> Didn't SP's regular passenger units for name
> trains have higher gearing for more than 65 mph? I
> would imagine the Rio Grand division gave
> passenger trains so room to run. I doubt they
> needed that much dual service power for the heavy
> express trains during the Christmas rush.
Yup. The Train Masters were primarily used in freight service while they were on the Rio Grande and Tucson divisions.
I'm not aware of any place on the SP (well, in the diesel age, at least) where tha Maximum Authorized Speed for passenger trains was higher than 79 M.P.H. WAF or JWL, do you know of any places where it was higher? That being the case, units with so-called "passenger gearing" regardless of manufacturer had their overspeed set at a nominal 83 MPH, while dual-service freight/passenger units with "freight gearing" had their overspeed set at 72. This would come into play with the SDP45s, which were delivered with 62:15 "freight gearing" and it quickly became obvious that they couldn't maintain the passenger schedules because of it, so they were re-geared. Likewise, when F-units with (62:15 or lower) "freight gearing" were used on passenger trains, they restricted to train to the lower speed for those units. (Actually, it was a piece of cake to cut out the overspeed on units with 24-RL brake equipment - been there, done that - but it wasn't a particularly good idea.)
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> Didn't SP's regular passenger units for name
> trains have higher gearing for more than 65 mph? I
> would imagine the Rio Grand division gave
> passenger trains so room to run. I doubt they
> needed that much dual service power for the heavy
> express trains during the Christmas rush.
Yup. The Train Masters were primarily used in freight service while they were on the Rio Grande and Tucson divisions.
I'm not aware of any place on the SP (well, in the diesel age, at least) where tha Maximum Authorized Speed for passenger trains was higher than 79 M.P.H. WAF or JWL, do you know of any places where it was higher? That being the case, units with so-called "passenger gearing" regardless of manufacturer had their overspeed set at a nominal 83 MPH, while dual-service freight/passenger units with "freight gearing" had their overspeed set at 72. This would come into play with the SDP45s, which were delivered with 62:15 "freight gearing" and it quickly became obvious that they couldn't maintain the passenger schedules because of it, so they were re-geared. Likewise, when F-units with (62:15 or lower) "freight gearing" were used on passenger trains, they restricted to train to the lower speed for those units. (Actually, it was a piece of cake to cut out the overspeed on units with 24-RL brake equipment - been there, done that - but it wasn't a particularly good idea.)
