Daryl Junior Train Controller

Location: Carrum Downs
I just watched a Youtube about slugs. They are used in the US They are a locomotive that has no engine but has driving controls. The loco it is paired with has connections to drive the traction motors. I think it is used like a super shunter and moves slowly. Presumably older locos are converted this way, apparently the engine is replaced with ballast (weight not stones).
I wondered why convert a loco this way? just use a functioning loco and convert it to used power for it’s traction motors with a dead engine and you can still use it like loco if you want. Possibly this is an alternative to scrapping locos.
Have slugs been used in Australia? I couldn’t find it in Railpage.

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  Noelwb123 Station Master

AN converted 4? of their 600 class Alco 2000 hp hood units to cabless " slugs" to be used with the ALF and CLF? Morrison Knudsen conversions of the former AL and CL class. I observed them in use on the Whyalla steel trains and I believe they were also used through the Adelaide hills on general freight. They weren't in use for very long so I imagine they were an expensive failure.

Noel

 

I just watched a Youtube about slugs. They are used in the US They are a locomotive that has no engine but has driving controls. The loco it is paired with has connections to drive the traction motors. I think it is used like a super shunter and moves slowly. Presumably older locos are converted this way, apparently the engine is replaced with ballast (weight not stones).
I wondered why convert a loco this way? just use a functioning loco and convert it to used power for it’s traction motors with a dead engine and you can still use it like loco if you want. Possibly this is an alternative to scrapping locos.
Have slugs been used in Australia? I couldn’t find it in Railpage.
Daryl
  james.au Minister for Railways

Location: Sydney, NSW
XRBs are also another example.
  lkernan Chief Commissioner

Location: Melbourne
XRBs are also another example.
james.au

XRBs have engines.
He's talking about units where the traction motors get power from a connected loco.
  YM-Mundrabilla The Ghost of George Stephenson

Location: Mundrabilla but I'd rather be in Narvik
XRBs are the exact opposite. They have engines but no cab. They, too, might have seemed 'a good idea at the time' but in practice are more nuisance than they are worth.
  Graham4405 The Ghost of George Stephenson

Location: In exile
I just watched a Youtube about slugs. They are used in the US They are a locomotive that has no engine but has driving controls. The loco it is paired with has connections to drive the traction motors. I think it is used like a super shunter and moves slowly. Presumably older locos are converted this way, apparently the engine is replaced with ballast (weight not stones).
I wondered why convert a loco this way? just use a functioning loco and convert it to used power for it’s traction motors with a dead engine and you can still use it like loco if you want. Possibly this is an alternative to scrapping locos.
Have slugs been used in Australia? I couldn’t find it in Railpage.
Daryl
TasRail's DV1 & DV2 are similar, but I don't think they have operational traction motors, only the cab is functional.
  lkernan Chief Commissioner

Location: Melbourne
I just watched a Youtube about slugs. They are used in the US They are a locomotive that has no engine but has driving controls. The loco it is paired with has connections to drive the traction motors. I think it is used like a super shunter and moves slowly. Presumably older locos are converted this way, apparently the engine is replaced with ballast (weight not stones).
I wondered why convert a loco this way? just use a functioning loco and convert it to used power for it’s traction motors with a dead engine and you can still use it like loco if you want. Possibly this is an alternative to scrapping locos.
Have slugs been used in Australia? I couldn’t find it in Railpage.
TasRail's DV1 & DV2 are similar, but I don't think they have operational traction motors, only the cab is functional.
Graham4405

Those are just driving cabs.  DV1 doesn't even have controls, just a space for a portable remote control pack to sit on the desk.
DV2 has multiple unit controls like a normal loco but no power or traction motors.
  Graham4405 The Ghost of George Stephenson

Location: In exile
I just watched a Youtube about slugs. They are used in the US They are a locomotive that has no engine but has driving controls. The loco it is paired with has connections to drive the traction motors. I think it is used like a super shunter and moves slowly. Presumably older locos are converted this way, apparently the engine is replaced with ballast (weight not stones).
I wondered why convert a loco this way? just use a functioning loco and convert it to used power for it’s traction motors with a dead engine and you can still use it like loco if you want. Possibly this is an alternative to scrapping locos.
Have slugs been used in Australia? I couldn’t find it in Railpage.
TasRail's DV1 & DV2 are similar, but I don't think they have operational traction motors, only the cab is functional.

Those are just driving cabs.  DV1 doesn't even have controls, just a space for a portable remote control pack to sit on the desk.
DV2 has multiple unit controls like a normal loco but no power or traction motors.
lkernan
So effectively DV1 is a "guard's van" replacement (as in this could be achieved by using a guard's van if one was available), but DV2 is similar to the above, but as per my post just a functional driving station.
  Noelwb123 Station Master

As I understand the BU's, as the AN slugs were categorized, were designed to spread the power from the ALFs and CLFs over 12 axles rather than just the 6 axles of the powered loco. This was supposed to maximize effective traction which would have been handy through the Adelaide Hills if it worked. They were probably at Whyalla being delivered or trialed after having been converted at the Morrison Knudsen facility there.
Seems quite ridiculous to take out the cab, a useful 2000 hp prime mover, and then replace it with a block of concrete and expect the overall power/traction equation to be improved?
Noel
  YM-Mundrabilla The Ghost of George Stephenson

Location: Mundrabilla but I'd rather be in Narvik
As I understand the BU's, as the AN slugs were categorized, were designed to spread the power from the ALFs and CLFs over 12 axles rather than just the 6 axles of the powered loco. This was supposed to maximize effective traction which would have been handy through the Adelaide Hills if it worked. They were probably at Whyalla being delivered or trialed after having been converted at the Morrison Knudsen facility there.
Seems quite ridiculous to take out the cab, a useful 2000 hp prime mover, and then replace it with a block of concrete and expect the overall power/traction equation to be improved?
Noel
Noelwb123
Could the same have been achieved by simply disconnecting the engine/generator and drawing power from the other locos.
  Daryl Junior Train Controller

Location: Carrum Downs
That's what I thought, the YouTube video said the engine was replaced by concrete or something but I thought it might be practicable to keep the locomotive as is but incorporate connections so the traction motors can be powered by another loco, but you can still use the loco as is.
Unless the loco had a worn out engine and was about to be scrapped.
But the slugs in the video looked new so there must be some advantage to a profit driven company.
I think the main advantage is that you save fuel compared to double heading.
But seems to be very specific such as balloons where minerals are unloaded or on steep grades. I don't think slugs would travel any great distance on the main line. Perhaps performs like a Garrett?
  ARodH Chief Train Controller

Location: East Oakleigh, Vic
The wiki page https://en.wikipedia.org/wiki/Slug_(railroad) has three types listed, yard, hump and road. The road slug type is no doubt being referenced in the YouTube videos. As the wiki says crews like to place road slugs as the lead loco so they escape engine noise, crew comfort is obviously a factor and I think the US has some odd systems in place in regards to engine power, run times and something else.

In all I see a Road Slug as a way to get a heaver loco, at a set power level but without exceeding axle loadings as the weight is spread across another set of powered bogies (on a completely separate frame). It's also another version of range extension as the tanks on the Road Slug can be plumbed to the live loco.
Another thought, replace the Road Slug ballast with batteries and boom! hybrid mode, pure electric mode where needed, diesel everywhere else
  KRviator Moderator

Location: Up the front
The other thing to consider, at least in terms of DC locomotives, you can operate at full traction HP at a lower road speed without running into the TM thermal limits. Every DC loco has such a minimum ruling speed, lest you overtemp the traction motor brushes & armature, and prolonged operation at speeds below this risks significant damage over time to the various components.

Spreading out the available power across double the motors allows this speed to be reduced, due to the lower individual TM current. One of my old 82 Class photos shows this current vs time relationship well on the ampmeter, with the 60/30/15/5 minute ratings.
  lowtensionearth Station Master

Their is a bit of confusion which I hope I can clarify. I worked for an US Class 1 Railroad which rostered a large number of varied slugs or TEBU’s (Tractive Effort Booster Units) as they were officially known.

KRviator is on the right. A DC locomotives diesel engine can deliver more horsepower than its traction motors can safely deliver to the rails at lower speeds due to slipping, heat and electrical ratings. The solution is to spread the diesel engines available horsepower and resulting electrical output across more traction motors giving a greater tractive effort. A Mother and Slug combination can move a significant amount more at lower speeds than a Mother unit can on its own.

Yard slugs are particularly useful as they allow yard locomotives to move longer cuts of cars with a single diesel engine. The resulting fuel bill is lower than employing two locomotives or alternatively one higher horsepower locomotive to do the same job.

The same principles apply to Road slugs on low speed switching turns. The slug helps the mother lift and accelerate the train generally to around 40kmh when it cuts out losing its power supply from the Mother. This drop off occurs when the Mother unit transitions from Series Parallel to Parallel and no longer has any spare electrical load to share with the slug. Road slugs allow for leading driving cabs, additional dynamic brake capacity and in some cases fuel.

In the USA locomotives are generally not kept in front line service as long as they are here in Australia. There is also a surplus of available older power at all times. Removing the diesel engine from a redundant locomotive to produce a slug is a well proven concept both on usage and financial grounds.

The failure of the AN BU class had more to do with MKA’s design as well as AN’s attempts to use them on traffic flows which weren’t traditional work for slug units.
  Galron Chief Commissioner

Location: Werribee, Vic
So given we are talking DC power applications, which seem to be on the way out, at least for any new mainline locos, even if you had a use case for the, the reducing number of DC locos makes using them even less viable.
  Sulla1 Chief Commissioner

I believe QR toyed with the idea of converting its 10 recently retired 1450s (G12 models) into road slugs in the very early 1990s. I guess the numbers didn't add up, but they might have been useful on the Toowoomba Range coal trains, which still operate with DC traction locomotives.

CSX remains a significant user of road slugs in the United States, mostly converted from GP30s, GP35s, GP39s and GP40s - and paired with GP40-2s. NS still uses a few yard slugs converted from GP9s and GP18s, but for many years also rostered a group of yard slugs converted from ex-Nickel Plate RSD-12s that would have been very similar to the 600/BU conversions carried out by Morrison-Knudson for AN.
  lowtensionearth Station Master

Sulla, very interesting and informative post regarding the 1450 class proposal. Thank you.

The term road slug is perhaps an I’ll fit because in reality road slugs perform most of their work on shunt or switching turns. They may work a hundred or so miles in a shift but it is rarely at mainline speeds. Using the local term they generally perform trip train work. Attempts to use them on mainline trains like AN attempted to do with the BU and how QR may have intended to use the 1450’s have rarely been successful. In US yards and on local switching turns where they were designed to be used slugs have proven to be immensely valuable however.

In regards to the NS RSD slug conversions their bogies were some time ago now replaced with spare EMD HTC trucks and motors. This came at some cost and engineering but reduced spare part requirements.
  speedemon08 Mary

Location: I think by now you should have figured it out
I believe QR toyed with the idea of converting its 10 recently retired 1450s (G12 models) into road slugs in the very early 1990s. I guess the numbers didn't add up, but they might have been useful on the Toowoomba Range coal trains, which still operate with DC traction locomotives.

CSX remains a significant user of road slugs in the United States, mostly converted from GP30s, GP35s, GP39s and GP40s - and paired with GP40-2s. NS still uses a few yard slugs converted from GP9s and GP18s, but for many years also rostered a group of yard slugs converted from ex-Nickel Plate RSD-12s that would have been very similar to the 600/BU conversions carried out by Morrison-Knudson for AN.
Sulla1
NS has a fleet of slug units mostly for yard work that look similar to normal road units from a distance built out of GP38/GP50 variants.

  Daryl Junior Train Controller

Location: Carrum Downs
Thank you for your comments which are informative.

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