Prof Klyzlr Posted November 24, 2013 Share Posted November 24, 2013 Dear Woodenhead, So to test if I get this notion of what a slug is, if DB Schenker took two class 66s and made one a slug, would they then be able to perform the heavy haul of a 60? Not knowing my UK locos, I can't comment in relation to these locos. However, the basic concept is: - Assume (on paper) that you have enough "horsepower" in the diesel prime-mover - which can generate enough Amps thru the Generator - to power the traction motors in a single loco (without over-powering and possibly damaging the traction motors) - to start moving from stationary the train/load in question BUT - you don't actually have enough adhesion (wheel<>rail friction) from that single loco to put all that power down to the rails, against the load in question.(you got all-the-power-in-the-world at your command, but the train is acting as a boat anchor, and all the loco is doing is slipping it's wheels...) What to do? Solution A : Add a 2nd full/proper loco under MU control Issues Arising: Sure you gained the extra axles to Up the Wheel<>rail friction,(which is the already-confirmed "weak link in the chain" under "standing start of heavy load" conditions), but you're also burning more fuel(remember, the Prime-mover+generator set in the First loco is technically enough to "start the load", why have 2x prime movers running when one will do?), and adding wear on what is a fully-functional loco, which could be better deployed elsewhere. Solution B : add a cabless "B-unit" (loco with full prime-mover/generator, but no human-drivable "cab/controls", literally only takes commands from the MU hoses) Issues Arising: All the maintainence and fuel bills of a "full loco", but none of the utility of a loco which can be "driven of it's own accord if required elsewhere". Solution C : add a Slug (no diesel prime mover or generator, just wheels and traction motors, and a ballast weight for adhesion) Issues Arising: - can only be used when recieving traction power from it's "Mother"/"Mate", otherwise needs shoving around like any other freightcar.- usefulness VS maintainence balance shifts once trackspeed exceeds a few 10's of MPH However, it's the simplest (and arguably cheapest) solution which literally "just bolts on an extra set of axles" to the existing "otherwise-powerful enough for the task at hand" loco, and thru spreads the available "pulling power" over more wheel<>rail fiction points. Similar analogies:- a 4-wheel car and a tracked vehicle may weigh the same,but because the tracked vehicle spreads it's weight over a larger contact/surface area, it can travel over "swampy" terrain whereas the car will sink - Consider a team of children capable of X kilo pulling force (tractive effort) VS a single strongman capable of same X kilo pull force(IE fair/equal in terms of raw pulling power), Everything else being equal, the team of children stand a reasonable chance of winning, because their force is anchored to the ground at multiple points, and spread over those anchor points. It only takes the single strongman to have a single stumble (pull-force<>ground anchor friction fail), and the kids will win... Now, it's worth noting however that Slugs provide advantages where the wheel<>rail friction "challenge" is greatest, IE from a standing start, or at slow speeds.(Think "drag freight", heavy-interchange a la IHB, or hump-yard missions). However, once the train is rolling, it takes comparatively minimal "additional pull-force/tractive effort+adhesion" to keep it rolling.(Grades and wind-resistance become bigger "power-sapping" factors once the trackspeeds get above 40mph or so...) As such, above a few 10s of MPH, the "extra axles/adhesion" which a slug gives is no longer an issue, or of particular benefit.(That slugs are often not equipped with a full traction-motor "transition system" means they effectively stop-contributing to the pull above their "sweet-spot",and become just-an-additional-car-in-the-train for the primary loco to haul). I hope this helps... Happy Modelling,Aim to Improve,Prof Klyzlr Link to post Share on other sites More sharing options...
TotalLamer Posted November 24, 2013 Share Posted November 24, 2013 Keep in mind that, though the Slug retains a separate road number from the mate, the pair are semi-permanently coupled and, in essence, one unit. Unless at the shop undergoing heavy repair, you'll never see a slug separate from its mate or vice versa. A quick "Cliff's Notes" version of what's posted above is this... say you've got a GP40-2 that's going to be used primarily in yard service. Well the extra 1000 horses it has over a GP38-2 pretty much goes to waste because, in yard service, you're at low speed and can't make full use of that power anyway without burning up the traction motors. So basically, at low speed, the prime mover has a large reserve of power available. So what you can do is just add extra traction motors in the form of a slug. Voila... more tractive effort! Link to post Share on other sites More sharing options...
Glorious NSE Posted November 25, 2013 Share Posted November 25, 2013 So to test if I get this notion of what a slug is, if DB Schenker took two class 66s and made one a slug, would they then be able to perform the heavy haul of a 60? Not sure they would do that with a modern working loco (but they still have a reasonably supply of demic shells they could theoretically use?) - so lets assume... The 66+Slug combo would be able to start a much larger train than any UK loco on it's own would - in fact probably long enough to not fit into UK loops, sidings, yards and give coupler issues if it wasn't something like a solidly buckeye'd coal train. Above a certain speed, that tractive effort stops being useful and you'd probably want it to switch itself off before 20mph or so - from that point on you have effectively 120t of dead weight to drag around and no extra horsepower, at which point it's a liability and the train will perform worse than if it just had the 66 on it. So, if you've a duty where you need to need to get more train weight moving, but you don't need to make it move fast, then a slug is a perfect solution, if you need to get that extra weight moving, and then need to accelarate that train up to a decent line speed (and over here, we do need that to happen) then two loco's would be the better solution. Link to post Share on other sites More sharing options...
Talltim Posted November 25, 2013 Share Posted November 25, 2013 Dear Woodenhead, Not knowing my UK locos, I can't comment in relation to these locos. Think of a variant of the SD40-2, squeezed into a tiny body Link to post Share on other sites More sharing options...
Adrian Wintle Posted November 25, 2013 Share Posted November 25, 2013 Think of a variant of the SD40-2, squeezed into a tiny body I thought the 66 was effectively an SD70 with a 12-cylinder 710 (instead of the 16), while the 59 was based on an SD40-2 (16-cylinder 645). Adrian Link to post Share on other sites More sharing options...
CraigZ Posted November 25, 2013 Share Posted November 25, 2013 CSX's road slugs (GP30 and GP35 based by and large) are not purely yard slugs but they do see a lot of service on lower speed lines - crews like them in the lead as they're very quite and smooth! Kansas City Southern built a number of road slugs years ago from F units...note the lack of fans on the roof. http://www.rrpicturearchives.net/showPicture.aspx?id=1205178 Link to post Share on other sites More sharing options...
Talltim Posted November 25, 2013 Share Posted November 25, 2013 I thought the 66 was effectively an SD70 with a 12-cylinder 710 (instead of the 16), while the 59 was based on an SD40-2 (16-cylinder 645). Adrian You are probably right Link to post Share on other sites More sharing options...
stock_2007 Posted November 25, 2013 Share Posted November 25, 2013 I'm rubbish at putting photos on this site, but how about a N&W H/hood Alco 630 with two slugs made from cut down FM Train-masters working the hump at Bellevue Link to post Share on other sites More sharing options...
yorkie_pudd Posted November 26, 2013 Share Posted November 26, 2013 Cheers to long island jack for starting this tread. As something I`ve never heard of or seen before in real rail & model worlds before as a UK northen lad like. I find this subject very interesting and very informational about the US slugs, but more so given me idea`s on layout I been planning with for awhile. It`s funny how threads like this remind you of things in past you had forgotten about., as in my instance this reminded me of an occasion in 1983/84 when I was driving 7.5 tonners. I was sent to then Sheffield steel now kumpo or something name like with a small hiab flatbed just shift stuff around site mid snowy winters day. I was in a hut having a brew and blokes were saying how bad rails were for wheel slip, to which one said he just coupled two 07`s or 08`s together to do the job. so back on topic this made me re-think about the industrial are of my plan and maybe doing a 08+08 slug conversion. I look forward to more pics and information of this subject. cheers ken edit: spelling doh Link to post Share on other sites More sharing options...
Prof Klyzlr Posted November 26, 2013 Share Posted November 26, 2013 Dear Craig, CSX's road slugs (GP30 and GP35 based by and large) are not purely yard slugs but they do see a lot of service on lower speed lines - crews like them in the lead as they're very quite and smooth! They key part of that sentence is that they see service on low-speed-lines. And yes, I can imagine they are relatively quieter, with the main "Noisemaker" an extra 50+ feet back from the cab... ;-) Happy Modelling,Aim to Improve,Prof Klyzlr Link to post Share on other sites More sharing options...
Prof Klyzlr Posted November 26, 2013 Share Posted November 26, 2013 Dear Ken, Cheers to long island jack for starting this tread. As something I`ve never heard of or seen before in real rail & model worlds before as a UK northen lad like. I find this subject very interesting and very informational about the US slugs, but more so given me idea`s on layout I been planning with for awhile. It`s funny how threads like this remind you of things in past you had forgotten about., as in my instance this reminded me of an occasion in 1983/84 when I was driving 7.5 tonners. I was sent to then Sheffield steel now kumpo or something name like with a small hiab flatbed just shift stuff around site mid snowy winters day. I was in a hut having a brew and blokes were saying how bad rails were for wheel slip, to which one said he just coupled two 07`s or 08`s together to do the job. so back on topic this made me re-think about the industrial are of my plan and maybe doing a 08+08 slug conversion. I look forward to more pics and information of this subject. cheers ken edit: spelling doh It wasn't technically a slug, more properly a B-unit, but if you happen to get your hands on a copy of March 1995 MR, check the SW1500 B-unit on the featured layout "Arcardia Terminal". Gorgeous little thing, and prompted me waaaaay back in my younger days to "B-unit" a B'mann GE44tonner to run with a 70tonner... ;-) Happy Modelling,Aim to Improve,Prof Klyzlr Link to post Share on other sites More sharing options...
RMweb Gold roundhouse Posted November 26, 2013 RMweb Gold Share Posted November 26, 2013 CSX's road slugs (GP30 and GP35 based by and large) are not purely yard slugs but they do see a lot of service on lower speed lines - crews like them in the lead as they're very quite and smooth! Kansas City Southern built a number of road slugs years ago from F units...note the lack of fans on the roof. http://www.rrpicturearchives.net/showPicture.aspx?id=1205178 The pair in my photos a few posts back taken at WIldwood in Florida used to work the local frieght along the main freight route thru Wildwood. Not sure if they still do and the short line that used to diverge here has been closed when looking on Google maps. Ian Link to post Share on other sites More sharing options...
Prof Klyzlr Posted November 26, 2013 Share Posted November 26, 2013 Dear RMWebbers, Figuring a "Hail Mary" was always worth a spin, I simply plugged the search term "slug" into rrpicturearchives.net... and low-and-behold, 79-odd pages of results... Have fun... ;-) http://www.rrpicturearchives.net/srchThumbs.aspx?srch=slug&search=Search Happy Modelling,Aim to Improve,Prof Klyzlr PS BTW, some of my faves just from Page 1... http://www.rrpicturearchives.net/showPicture.aspx?id=3392809 (ex GE 8- or 9- ?) http://www.rrpicturearchives.net/showPicture.aspx?id=3232440 NS does "taipan" looking dynamic-braked slug http://www.rrpicturearchives.net/showPicture.aspx?id=3219931 Fresh slug? (escargo de manifique?) http://www.rrpicturearchives.net/showPicture.aspx?id=3107643 even gensets can be paired with slugs... http://www.rrpicturearchives.net/showPicture.aspx?id=3378029 Ultra-long hood? Nah, just a slug... http://www.rrpicturearchives.net/showPicture.aspx?id=3019826 BNSF GP+slug set hiding on what looks for all the world like a Inglenook? http://www.rrpicturearchives.net/showPicture.aspx?id=3332031 For the Guildford fans, a relatively tall slug... http://www.rrpicturearchives.net/showPicture.aspx?id=3337680 Could be a B-unit or "calf", could be a slug? Link to post Share on other sites More sharing options...
Talltim Posted November 26, 2013 Share Posted November 26, 2013 How would you do sound for a slug? Presumably they still have traction motor noise, blower noise, brake noises and even, in one of the Prof's examples above, dynamic brake noise. Is it possible to turn down the prime mover noise to nothing on a dcc sound chip, leaving the other sounds? Link to post Share on other sites More sharing options...
dave_long Posted November 26, 2013 Share Posted November 26, 2013 I've got a thing about the Winchester & Western, they have what they call a unique slug. Retro fitted with a cab due to many crossings and reverse moves in Winchester. It has a SW cab on and old rs11. http://www.pbase.com/vamidlandrr/image/110435073 Link to post Share on other sites More sharing options...
Prof Klyzlr Posted November 26, 2013 Share Posted November 26, 2013 How would you do sound for a slug? Presumably they still have traction motor noise, blower noise, brake noises and even, in one of the Prof's examples above, dynamic brake noise. Is it possible to turn down the prime mover noise to nothing on a dcc sound chip, leaving the other sounds? Dear Tim, You've got it in one. TSUs and Digi Soundbugs both have specific "primemover" volume CVs which can be set to Zero, independent of the "master volume" CV. This same technique is perfect for applying sound to units like RCP remote-control units... Happy Modelling, Aim to Improve, Prof Klyzlr Link to post Share on other sites More sharing options...
yorkie_pudd Posted November 26, 2013 Share Posted November 26, 2013 Dear Ken, It wasn't technically a slug, more properly a B-unit, but if you happen to get your hands on a copy of March 1995 MR, check the SW1500 B-unit on the featured layout "Arcardia Terminal". Gorgeous little thing, and prompted me waaaaay back in my younger days to "B-unit" a B'mann GE44tonner to run with a 70tonner... ;-) Happy Modelling, Aim to Improve, Prof Klyzlr Thanks for the reply and I realise two 08`s are just 2 coupled prime movers, my thought was like many an example pictured here 1x 08 prime mover and convert the second 08 to just chassis and boxed hood cut down like the true slugs appear etc. Some great pics in post 38. cheers. Link to post Share on other sites More sharing options...
49395 Posted November 26, 2013 Share Posted November 26, 2013 so back on topic this made me re-think about the industrial are of my plan and maybe doing a 08+08 slug conversion. I look forward to more pics and information of this subject. A class 13? http://www.rmweb.co.uk/community/index.php?/blog/1198/entry-10812-the-master-and-the-slave-creating-a-br-class-13-pt1/ Link to post Share on other sites More sharing options...
yorkie_pudd Posted November 26, 2013 Share Posted November 26, 2013 A class 13? http://www.rmweb.co.uk/community/index.php?/blog/1198/entry-10812-the-master-and-the-slave-creating-a-br-class-13-pt1/ Cheers Mike your a star. great link and read and to be honest was only a thought after reading this thread. my original idea was a working 08 and one class 17 clayton. I see in that thread link they cut the cab down but left the main engine hood height intact, my rough thought like he US slugs was where 08 cab was cut down that similar level right across. I saved that thread but only downside as usual you get an idea then see something else, all plans go out the window again with more idea`s of oooh I could do this instead or how about that lol. again cheers for the link. Link to post Share on other sites More sharing options...
Glorious NSE Posted November 27, 2013 Share Posted November 27, 2013 Don't think the 13 was a slug, it was a powered unit, just without a cab - like a B unit, but in this case 'hardwired' to the controlling 08 rather than being able to MU. Link to post Share on other sites More sharing options...
Talltim Posted November 27, 2013 Share Posted November 27, 2013 While it shouldn't stop you building an 08 slug set, I think that in real life it wouldn't work very well. Slugs work because the connected loco has more power produced by its generator than is needed at slow speed (to allow them to have enough power at higher speed.) but not enough grip. An 08 isn't designed to go fast so presumably only really had enough power to pull within the limits of its adhesion at slow speeds. A class 17 slug set would be cool tho. Link to post Share on other sites More sharing options...
RMweb Gold roundhouse Posted November 27, 2013 RMweb Gold Share Posted November 27, 2013 A class 13 pair in CSX NY2 livery anybody?? Link to post Share on other sites More sharing options...
Adrian Wintle Posted November 27, 2013 Share Posted November 27, 2013 A class 13 pair in CSX NY2 livery anybody?? YN3 is more intimidating... Link to post Share on other sites More sharing options...
Glorious NSE Posted November 27, 2013 Share Posted November 27, 2013 A class 17 slug set would be cool tho. Or 20s.... (Or a 20/17 combo...) Link to post Share on other sites More sharing options...
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