Western Railroad Discussion > Slave vs. Slug

Whats the diff?

I think I know a slug is a non-engined vehicle,
taking power from another locomotive, with motored
trucks and dead weight added for slow speed
pulling power, but what is a slave?

I ask as I heard MKT #401 was a slave.
(Please no pics of #401 - its so butt-ugly!)

My understanding is that a slave is a mid-train or rear-end locomotive controlled by radio from the head-end. Distributed-power locomotives fit this definition of slaves.

In Canada they refer to remotely operated mid train locomotives as slaves.

Without trying to get too technical so everybody can understand this, a slave is a remotely controlled locomotive such as a DPU.

A slug is a locomotive that has no prime mover put gets it power from another locomotive in the consist. A slug has traction motors, and, in some cases, dynamic brakes.

The idea behind a slug is to have, as an example but not limited to, a 3-unit hump consist (SD-38, slug, SD-38) like what use to be at West Colton, CA., where you only have two diesel engines powering three locomotives. The locomotive on the west end would develop power for itself and the traction motors on the west end of the slug and the locomotive on the east end would power itself and the traction motors on the east end of the slug. This also happens in dynamic braking too. This way you have one less diesel engine to maintain while you can still have the same tractive effort as what, in this case, you would have with three SD-38's.

Any questions? Any answers? Anyone care for a mint?

steamjocky

ArgyleEagle Wrote:
-------------------------------------------------------
> Whats the diff?
>
> I think I know a slug is a non-engined vehicle,
> taking power from another locomotive, with motored
>
> trucks and dead weight added for slow speed
> pulling power, but what is a slave?
>
> I ask as I heard MKT #401 was a slave.
> (Please no pics of #401 - its so butt-ugly!)


Shane, that is a local application of the word "slave", which you can't use anymore on the railroad due to political correctness--but the 401 was really a slug, or in terms of acronyms, a Tractive Effort Booster Unit (TEBU) as the SCL called em. A Slave anymore is really a DPU. On the BN, their B30-7A(B) cabless units, while certainly not "slugs" were called Slugs because they didn't have a cab. Crystal clear?

So, slug is TEBU, a slave is DPU.

OK?

Have slugs ever been used outside of yards?

Have they ever been utilized on trains going long distances and not simply in a consist because it was being moved to another location?

How about leaving yards to work on local switching jobs?


Thanks for your replies,


George,
Fontana,Cal.

George asked this:

"Have slugs ever been used outside of yards?"

Yes, the photo here is of a unit used on the OC&E in southern Oregon. I'm not a "nuts & bolt" type guy, but as I understand it, at low track speeds two locomotives can provide enough electricity to power more trucks without the cost of a prime mover.

OC&E ran Locomotive-Slug-Locomotive powered logging trains from Sycan, Oregon to Klamath Falls, Oregon.

I'm sure that class ones did the same with yard transfer jobs.

Jimmy "B"

---

Although on this list there are many that have a better understanding of this, hopefully one of them will speak up. Anyway, here goes.

Harris, a maker of two-way radio gear, commercially pioneered this system of head-end power controlling either mid-train or rear train helpers. There was first Locotrol and then Locotrol II.

The Canadians seemed to have been the first folks to really utilize this technology. The Espee stepped up in the states and did use this new radio technology. In a number of purchases of SD40T-2s. SD40T-2s below 8350 and above 8300 purchased by SP were masters, those SD40T-2s above 8350 but below 8400 were slaves.

Unlike today's DPU units, which can either head a train or push a train as helpers, the Locotrol locomotives were either master or slave.

It is my understanding that snoot SD40s were designed to hold the Harris radio equipment as either masters or slave units.

Jimmy "B"
Reno, NV

FGS Wrote:
-------------------------------------------------------

> Harris, a maker of two-way radio gear,
> commercially pioneered this system of head-end
> power controlling either mid-train or rear train
> helpers.

To give credit where it's due, the designer of the system was the industrial controls division of North Electric Company of Galion, Ohio. That division was sold to Radiation Corporation of Melbourne, FL, before the first commercial systems were sold.

Radiation was in turn eventually merged into Harris as their controls division. With the dissolution of the GE/Harris joint venture, the railway products are now part of GE Rail.

The Locotrol design was an adaptation of North's existing systems used to control remote gas line pumping stations and electrical substations. It was adapted at the request of Southern Railway, which was the purchaser of the first systems. KCS came soon after, followed by a number of railroads like the CPR. Of all of the early railroads, the CPR has probably been the strongest supporter from the beginning. Other railroads, like BN, essentially stopped using Locotrol for a period, but have more recently re-embraced it.

Speaking of slugs..... Did KCS or MKT convert some F units into slugs?

Thanks,

Russell
SD9E

CSX operates more than 100 "road slug" units, rebuilt primarily from GP30 and GP35 platforms and all mated to GP40-2's. They still have full cabs and hoods, but all external openings related to a prime mover have been blanked out. There is still a single fan for the dynamic brake. Essentially what you have is a GP40-2 worth of horsepower (3,000 hp) but eight axles instead of four -- so essentially it's like a pair of GP7s but with just one prime mover. This power is used primarily in local and mine-run service, but can often be seen on the road, either in transit to/from servicing points or assigned to drag freights out here in the flatlands.

Oh, and the crews love to have the slugs in the lead, because it's real quiet with no prime mover making a racket out back.

During the 1980s, Guilford had a TEBU slug unit, B&M 100, mated with a pair of B&M GP40-2's (300 & 301), and this trio was well known throughout the system as "the slug set." But by the early 1990s it was broken up, with the slug retired and eventually the GP40-2's were returned when their leases expired. The B&M 100 looked like a yard slug, with no cab, but I mention it because it was assigned to road service.

P.S. CSX recently gutted a bunch of old GEs and GP40s and outfitted them for use as remote-control radio platforms, but calling these things "slugs" is a mistake, because they don't have traction motors. The most popular term for the radio-control mates is "drone." CSX has since decided that old bulkhead flatcars can be used for this purpose instead of old locomotives, so the creation of "drones" appears to have stopped.

Run8

Thanks for that clarification, good stuff.

Jimmy "B"

In the mid-70's, the SP converted one FM Trainmaster into what I think they termed a "braking slug." There wasn't much left of it but the frame itself.

What was this used for - dynamics only? What was its disposition?

John Maky
spdonner@sbcglobal.net

spdonner Wrote:
-------------------------------------------------------

> In the mid-70's, the SP converted one FM
> Trainmaster into what I think they termed a
> "braking slug." There wasn't much left of it but
> the frame itself.
>
> What was this used for - dynamics only? What was
> its disposition?

In early 1974, retired FM Train Master 3028 was sent to West Colton and m.u.ed with a six-axle yard unit (usually an Alco C628 or C630). The 3028's carbody was not modified in any way. The prime mover had previously failed, and the unit was used merely for added air braking.

The experiment was moderately successful, so SP planned to covert the hulks of four retired Train Masters (3025, 3027, 3032 and 3034, as I rcall) to braking sleds by basically stripping off everything above the level of the running boards and filling the frame with added ballasting material. New numbers would be in the MW9100 thru MW9103 series.

Work began at Sacramento on the first one, 3027 to MW9100, and the unit was sent to West Colton. The other three conversions were never done.

All of the above were eventually sold for scrap.