GE -7 Power Reduction Control

[Spur44]

Hi guys. I'm looking for a bit more -7 info. I've noticed a lot of the four axle -7s had a power limit switch just under the Engine run breaker. Its listed as Notch 7 and Normal and from reading some manuals I have a bit of an understanding of what it did. Now, on the B36-7s, and I'm not sure if this was across the board but at least some, had a power reduction control just above the rear headlight switch. It consisted of a switch and a dial with min/max listed. That is what I am really fuzzy on how it functioned and when? Was it at certain throttle settings or any notch? Was it used in addition to the power limit switch or completely separate?

[Wayside]

Notch 7 power limit was a common feature on GE units for years. In all my time spent operating these units, I can truthfully say I never had the need to use it. I'm not even sure if it was a trainlined function or worked only on the unit that had the switch activated.

The power reduction feature is/was used for low speed operation, such as dropping ballast or shoving a hump drag. We had this feature on the PC/CR U23C units, and used it for humping.

[Spur44]

Ok that makes sense. Was trying to sort out what I've seen it on. I've got a pic of it on CSX 5538 ex C&O 8256 with the power reduction control. I could have swore I saw it on a control stand for a Conrail B36-7 but I'm probably completely wrong on that. In my thinking it doesn't make sense to have it on a unit that was more for high speed service.

[WVU]

I had a Conrail C36-7 with CHEC II Excitation Print and it did have Power Reduction (HUMP CONTROL) but they were not using it for RTL (Trainline). I would have to locate a Conrail B36-7 Print verify if the B36-7 units with CHEC II Excitation had HUMP CONTROL. My guess is they did.
I did have a Seaboard (L&N) CSX Print for a B36-7 with CHEC II Excitation and it had Power Reduction (HUMP CONTROL) with RTL operation.

[Spur44]

Went digging through pics again and found the B36-7 that had it. It was actually the 5902, ex SBD and above the handwritten number on the control stand was a Q so I'm guessing that made me think Conrail. Anyway, I failed to put the number range together in my head lol. What is 'RTL Operation'? So as for hump control, it was only used at really low speeds? Seems like a bit of a waste on those units. One of the last mainline trips I caught with a B36-7 in the lead was on a 10,000 ton phosphate train with two SD40-2s. We almost stalled in locations that I had never come close to stalling on before. Fun trip with that slippery beast in the lead.

[Engineer Spike]

You are talking about two different features here. The notch 7 switch makes the lead unit load to only notch 7. This is because the leader is most likely to slip. CP had a similar application in the SD40-2s called power reduction. It made the unit only respond to the odd numbered notches. If the throttle was in 2, the unit would stay in 1, and if in 4, the unit would still be running at #3 power levels.

The second feature is a rheostat. This feature permits power in each notch to be finely regulated. It is useful for humping, or continuous flood loading hoppers. This is trainlined. It was later replaced by pace setters. Those devices allowed a number to be entered, and the power would be regulated to that speed. There was no need to adjust the rheostat, to keep a constant speed.

[Typewriters]

The Notch 7 switch goes back to the U25. On some roads U25B units trailing old EMD’s would have the switch set on procedurally as a crude form of power matching although U25/U28 units had a thermal automatic power matching installed standard.

[Spur44]

Can anyone tell me what the annunciator light would say for the power reduction control on this unit? Everything else I can make out through various pictures.

Power Reduction Control

Annunciator light - ?
Dial - Min - Max
Switch - Local - Off - Main Line

Can anyone tell me what the difference would be between the Local and Main Line settings?

Pic by Brian Oliver

[Wayside]

Is that "Main" Line or "Train" Line? If set to Train Line it would reduce power to the whole consist through the jumper. Local would be just the isolated unit.