EMD turbos lashed to non-turbos

[broncoman]

Question number 255. I have noticed that UP has been using turbo and non-turbo mixes for local duties in the area and I was wondering if this would be a problem or at least harsh if your in the cab ride was as they engines load differently. The mixes are usually GP39-2 or GP40-2s with GP38-2s or even a GP-15. I am sure the Turboed locos in the mixes are indeed turboed by stack number and turbo whine, was just curious if anyone out there has operator wise has been in this situation.

Dave

[oltmannd]

Shouldn't be a big deal. Loading rates should be pretty close. Would be nice to hear from an engineer on this one, though.

[Anonymous]

The units should load the same, it's just a matter of horsepower. For local and yard work it doesn't matter. Dave, are you talking about the yard in Roseville??????

[kenneo]

The only problem will come later with the turbo. The clutch and gears will wear faster when used in switching since they keep engaging and then disengaging. It will need service/repair sooner then if used in road service.

[M636C]

broncoman

Some time ago, the speed. power and fuel consumption data for EMD Blower and Turbo 16 cylinder 645 engines was posted on the forum. The proportion of power in each throttle notch is roughly the same, so when a GP40-2 is producing 2000 HP, a GP38 coupled to it in MU will produce 2/3 of 2000 HP, about 1333 HP, and they will be sharing the load in proportion all the way from idle to Notch 8.

So when the Turbo engine is running with the turbo clutched in and driven by the engine, it isn't behaving exactly like the blower engine of the same type, but as a more powerful engine at the same proportion of power.

There isn't a stage where the engines are behaving the same and suddenly the turbo kicks in an and makes the turbo engine more powerful. It is the same proportion more powerful at every notch above idle.

Peter

[broncoman]

QUOTE: Originally posted by drailed1999

The units should load the same, it's just a matter of horsepower. For local and yard work it doesn't matter. Dave, are you talking about the yard in Roseville??????

They are the ones that work the locals to Lincoln, Marysville, etc.
Haven't seen the same set twice.

Peter, I was a little confused based on another post that was saying that GP40-2s and SD40-2s don't work well together unless they were in the upper notches. Is this a different problem?

Dave

[M636C]

Dave,

Since the GP40-2 and SD40-2 have exactly the same engine, they should share the load equally. However, the rated speed at a given power will be higher for the GP40-2, because it has only four motors. At lower speeds, the GP40-2 would be running with a higher current through its motors than the SD40-2 at the same speed, and the GP40-2 could overheat its motors.

If the two were running a light fast train, like an intermodal, there shouldn't be a problem, because they wouldn't be in the low speed zone long enough to damage the GP motors. If you coupled a GP in with a few SDs on a slow coal train in mountain territory, it would be at risk.

EMD have a power reduction feature that drops the power of a GP40-2 or similar unit to avoid the overheating problem, but then the GP isn't producing the same power as the SD. If you were running in such a way that the power reduction cut in and out, the GP40 might not appear to be doing its fair share.

It's probably a bit more complicated than that! But I think the different minimum speed at full power and power reduction is the basis of the comment that they don't work together well.

Basically, a GP40-2 is happy running fast, while an SD40-2 can run fairly slowly all day without a problem.

Peter

[broncoman]

Thanks Peter.

On that note have you ever heard of a railroad that tied power output onto one bus to share amongst all traction motors.
I have heard UPs mother-slug-mother setup (GP-40-2-slug-GP40-2) shares the power produced amongst each other, all traction motors share same power. Have you ever heard this done on a road unit setup?

Dave

[CSSHEGEWISCH]

Several classes of straight electrics plus RDG's original MU cars were equipped with bus connectors to allow the necessary current draw through one pantograph. VGN's EL-C's and MILW's boxcabs were so equipped, there may be others.

Slugs are usually wired to draw from one mother's main generator, although some may be set up to draw from one mother for the motors on one truck and from the other mother for the other truck. TRAINS had a pretty good article about this in the early 80's.

[broncoman]

That would seem kind of scary to pull that much power through one pantograph

[M636C]

Dave,

The Australian National tried to build some road slugs and converted their AL class locomotives to slug mothers. The AL was basically a lightweight SD40-2 in a double end boxcab carbody, and in the conversion one cab was blanked off, giving an odd appearance.

This whole episode was a comedy of errors, but there were some principles worth mentioning - the slugs only work at low speed, where a GP40-2 for example, has excess power. At higher speed, the slugs become extra vehicles being hauled, because the diesel loco needs all its power to run its own motors at high speed.

AN selected four "600 class" as slugs, these were Alco DL541s, a sort of export RSD12 with six powered axles. However as road slugs, the "BU" units were rebuilt as A1A-A1A with four EMD motors and their own dynamic brakes. Each of two ALF units powered the two motors on its end of the slug, giving effectively two eight motor locomotives to start heavy trains, and two six motor units at higher speeds. The slug could of course provide dynamic braking on falling grades without draining power from the control units.

The idea was given up after a couple of trials. The main effect was the loss of the Alcos, given that the three remaining DL541s are earning money in the lease market now.

I expect that the UP units are set up similarly, and each GP40-2 would power the two slug motors on the near end of the unit, so at low speed you have two SD40-2 (equivalent) and at higher speed, the two GP40-2 units and a heavy car with no loading in it.

I don't think it can be considered as all motors sharing power on a bus.

On an earlier subject, the British Rail Class 33 1550HP Sulzers, known as "Cromptons" because thay had Crompton Parkinson electrical equipment, did have field weakening on the motors, which worked a bit like an overdrive gear. By weakening the motor field, the motor resistance, the back EMF, is reduced, and the motor spins faster at the same voltage. On DC series wound motors, it is the input voltage that controls the speed. One ex BR driver at Mt Newman wanted field weakening to help increase the speed range of the C636s to avoid train bunching on dips crossing rivers with loaded trains. It might have worked, but most people didn't understand what he was saying, and we didn't have the ability to rewire the C636s for field weakening anyway.

Peter

[broncoman]

Peter,

It sounds like your theory of how UP wire their slugs is more correct. It would seem though that on this setup you run into the possibilty of problems at the transition point. It would seem that as you came upon a grade even the slightest that brought down the speed of the train it would switch back unless this switch was a manual thing. Did the AN try this on road haul situations. Is the length of trains in Australia different than that of the US? How about severity of grades? Are the C636s still active?
Thanks for you information.

[Anonymous]

Back in the dark ages, Seaboard Coast Line (remember it?) bought a slug of GE U36bs - 3600 HP, 4 motors.

They were fine when you could keep them over 25MPH, but below that, especially in the rain, they'd slip out of a sandhouse.

So GE sold SCL some road slugs called "Mates" - Motors for Additional Tractive Effort. There were two kinds - single and double ended. The single-ended mate was to attach to a single U36b and made it, in effect, to a U36D - eight traction motors taking power from a single 3600HP power plant. They were used in the phosphate mining territory of south Florida.

Double-ended mates were designed to couple between two U36bs; the traction motors on one end took power from one U36 and the other end from the other. The result was a combo about the equivalent of two U36Cs, or two SD45s (actually, they were better than two SD45s on SCL, because you never saw an SCL SD45 that didn't have a couple of traction motors cut out).

But in the mountainous regions of SCL, four units of power were needed, so they'd couple up another U36b to the three-unit mate consist. The result was that, on the mountain in the rain, the "bachelor" (the U36b not supplying a mate) would slip just like always.

But GE was happy. They sold a hundred or so engines not good in the mountains, and then sold them some additional jewelry to make them good.

Old Timer

[GMS-AU]

Are the turbos on EMD's not direct gear driven. Do they have a clutch system and if so what inducts the fuel/air at low revs? Is the clutch a centrifical one and engages at a certain rev limit?

[broncoman]

QUOTE: Originally posted by GMS-AU

Are the turbos on EMD's not direct gear driven. Do they have a clutch system and if so what inducts the fuel/air at low revs? Is the clutch a centrifical one and engages at a certain rev limit?

They are gear driven with an overrun clutch.

Old Timer,

I know the management may be a little out of the loop with regards to how stuff works, but didn't SCL turn around and purchase a large number of B30-7s also. Wouldn't they have the same problems with these?

[BigJim]

To answer the original question, there is no problem mixing the two together. There is more of a problem mixing units together with different electrical systems, i.e. new and older types.

The problem that I speak of is "transistion". Some units change transistion more abruptly than others. This is not only a factor among different classes of locomotive but also units within the same class. Some make the change smoothly, some make a hard abrupt change that will make you start praying the knuckles don't break.

N&W was a pioneer in slug technology. They started out in the yard and after some time built some for the road. These road slugs were a real bane to those that had to operate them. They worked fine up to about 15mph at which time they cut out. So what happened was it made for a very slow run. Sure it would just pull the tonnage over the hill at 15mph or below, but when the grade wasn't so steep the slugs quit working and there wasn't enough power to make track speed or get even close. Kind of a catch 22.

[broncoman]

QUOTE: Originally posted by BigJim


N&W was a pioneer in slug technology. They started out in the yard and after some time built some for the road. These road slugs were a real bane to those that had to operate them. They worked fine up to about 15mph at which time they cut out. So what happened was it made for a very slow run. Sure it would just pull the tonnage over the hill at 15mph or below, but when the grade wasn't so steep the slugs quit working and there wasn't enough power to make track speed or get even close. Kind of a catch 22.

I had asked this question on another post with no answer. Do you happen to know when NW retired the trainmaster slugs, and if they ran them with mothers other than the C630s?

Dave

[railroadmike11]

one thing no one has mention is that turboed locomotives has to be ran at near max power sometime. this is to spin up the turbo to remove carbon deposits. most times you can tell when a turboed engine has set idling, or ran at low rpm, is the shower of sparks at nite you can see coming out of the stack. that is why you didnt see no turbo engines in local service in earlier times, now it is just put an engine on the train and get it out of the yard! as to the transitioning, most engines do a foward transiton at a range of 20 to 30 mph. i personlly dont fear that transiton. the backwards transiton is i fear. the range on that is around 20 to 15 mph, which is a hi amp. slow speed situation. the engines will drop the load it has momentary transiton then reload it self. most engines dont do this graceful at all. in the rain on a side of a hill i wait for the lunge to occur, that can get ugly. and finally the slugs i have to work with are mated to old sd 35s that have been rerated th sd 38s, the slugs them selves are cut down sd7/9s. they pull real good at 3mph. and when they are moved on the road both mother and slug has to be isolated account the engines wont transition. i hope that awnsers some questions. thanks mike b. bnsf engineer

[BigJim]

"Do you happen to know when NW retired the trainmaster slugs, and if they ran them with mothers other than the C630s?"

Not trying to be short with you 'cause I'm out the door to work...No, I don't know when the were retired. There is one still sitting beside East End Shops that I suppose is waiting to be scrapped. Get your pictures NOW. Yes they were mated to other units although I never paid much attention to them. Had to be an SD35 or SD40. GE's weren't used.

[Rodney Beck]

Loading is no different between them, the major differance is while switching and kicking cars the non turboed locomotives engine respondes better I.E. turbo lag when it goes from notch 1 to notch 8 their is some lag. When I work road switchers or locals it does not make a differance to me.

 

Rodney

[SALfan]

Many years ago (1960's?) there was a model of GM locomotive (I think) that was sometimes slippery, but when coupled with a different model it would settle down and pull well.  Believe the slippery one was a GP30 or GP35, but am not sure.  Also don't know if the model it was coupled to was turboed or not.

[WSOR 3801]

Usually when I switch with a turbo engine, I take it out to Run 6 when kicking.  They don't always like to go to 8 from idle.  I had one shut down on me when I tried it.  SD40-2 in 6 is around 2000 hp, same as GP38 or SD20 in 8, so it works out. A SD20 kicking in run 8 works pretty good, less slippery than a GP38.  Need cars with air to stop, though.

Some of the engines transition like they have a shift kit in them, pretty quick.  Others take a while.  Changing direction takes longer in a six-axle, more going on in the electrical cabinet.