Whenever large existing mainline steam locos (i.e. SP 4449, UP 844, ATSF 3751) make special runs in the modern-day, they’re usually MU’ed to modern diesel locomotives, for additional pull, but mostly for head-end-power. Do the steam locos have the ability to control the diesels, or do the diesels need to manually run with an additional engineer running them?
Last year when I saw 765 there was in crew in the NKP unit (#8100 ES44AC).That diesel isn’t for show or head end power…Its back up in case 765 has a road failure.
It depends on the locomotive. IIRC, the SP 4449 and maybe the UP 3885/844 have an EMD Throttle stand in the cab, and MU cables on the rear of the tender. They do not MU the engines together - there is no connection between the steam throttle and the diesel throttle. If they need more power, they just advance the diesel controller in the steam engines cab. This eliminates having to have someone in the cab of the diesel. The ‘pilot’ engineer from the host railroad will be riding along with the steam crew. Normally the diesel is just along for the ride, and is providing HEP for the trailing passenger gars if needed. The diesel is just an ‘Insurance Policy’ if they have a steam locomotive road failure. I am not sure if MILW 261 had this arrangement, but I will be viewing it this spring at the local NMRA-TLR meet in Minneapolis.
Jim
Thanks for the throttle info re: 4449.
When a diesel is added to provide HEP, are they put on “neutral” or do they run in the consist?
Here’s some pictures of folks installing an MU setup on SP&S 700 (a 4-8-4):
http://www.sps700.org/gallery/02mu.shtml
Unfortunately, they don’t show the finished job. When I visited the 700, I noticed a box on the rear of the tender with a big old “EMD” on it–something you don’t expect on the flanks of a steam locomotive. That was the MU receptacle cover.
Ed
There never is a ‘consist’ the trailing diesel is not picking up the throttle action of the steamer. When a diesel is providing HEP, it usually is running at something above idle. Back in the days of the Amtrak F40PH, the engine ran at a set speed if providing HEP to the train. It sounded like it was going full tilt as it slowed at a station for passengers. Some of the current engines have an adjustable electrical HEP output, and ramp up the diesel as needed to provide for the HEP load - all automatic. IIRC, the Amtrak P40/42 ‘Genesis’ engines do this.
The steam engine throttle does not have 8 matching throttle positions and even if it did, the power output at each position would vary depending on steam pressure/load/reverse gear setting. A diesel-electric locomotive has specific RPM output at each throttle notch position. The diesel throttle in SP 4449 is manually ‘notched up’ if they need assistance going up a grade or to make track speed.
Jim
On the UP trains the diesels do not provide HEP, they are only there to pull the train.
Yeah, I figured that. That’s why you’ll always see an Amtrak loco thrown in there.
Not just for HEP, there a mutlitude of reasons for including diesels:
Often a requirement for insurance purposes
Ability to accelerate the train to track speed- typical UP practice
Dynamic brake capabilty
Back up power
Abilty to assit maintaing track speed and assiting with grades
Useful if switching moves are required
BTW, UP has power cars specifically designed to provide HEP.
Dave
Correct about the HEP, but when I talked to the crew when the 844 visited La Grande, OR, the diesel’s main function was to provide DYNAMIC BRAKING in the mouintains. I wont say that they never notched up the throttle on the diesel for a little boost, but the steam crew said that DB was THE reason that the diesel was there.
UP typically does not send a diesel as “Back Up” protection, the 844 and the 3985 have seen many miles service without a diesel being along for the ride.
Doug
Actually in UP trains you will rarely if ever see an Amtrak engine (I can’t remember ever seeing one). The UP has power cars that supply HEP.