QUOTE: Originally posted by owlsroost QUOTE: Didn't the Ruston engine have a maximum RPM of about 1100? The Ruston 16RK3CT in the 56 was rated at 3250hp at 900rpm (according to my stock book). In relation to the 66's, I wonder if the modified/lightened version of the radial-steering truck doesn't work as well under a much lighter (compared to an SDxx) locomotive - in terms of keeping all wheels in good contact with the rails and minimising weight transfer between axles. I think that the EMD wheelslip control (from memory) works at the truck or locomotive level, which is somewhat less sophisticated than the system on the Brush-built class 60's which controls each axle independantly. Any comments Beaulieu ? Tony (and thanks for the clarification Simon)
QUOTE: Didn't the Ruston engine have a maximum RPM of about 1100?
Thanks to Chris / CopCarSS for my avatar.
QUOTE: As a lover of the 40's, and then of the smaller Sulzers I've never been a great admirer but six objective HO/HM men gave me some compelling arguements and some scary stories!
QUOTE: Originally posted by beaulieu Yes Tony, that is the same RPM as the 645, but I still wonder about the torque curve matching due to GM's use of a mechanical assist turbocharger on their diesels. It produces a different curve compared to diesels with free-wheeling turbos. Regarding the Class 66 slipping problems, the HTCRs under the Class 66s should be better than the HTCs under the Class 59s for adhesion due to better wheel to rail geometry. Both designs are bolsterless. The traction motors are not seperately exciteable like the Class 60, but then the Class 66 was not built for the same duties as the Class 60 even though it is being used for some of them. The Microprocessor controlled Wheelslip system in the Class 66 should be better than that in the Class 59 since is a development of the earlier system with faster more capable processors. The big IF is with the software. The Class 59 uses simple feedback processors with EEPROMs, the Class 66s microprocessors can be updated by just plugging in a Laptop and updating the program. Like most equipment of this type how well it works is down to how good the software and hardware engineers are. I believe that GM was skimping during from the mid eighties until EMD was sold. It shows in EMDs sales performance in North America until the recent sale. EMD was just hanging on. Suddenly in the last year they have moved back into a competitive position versus GE.
QUOTE: Originally posted by owlsroost I agree with you that the power/torque characteristics of the Ruston and EMD engines would be different (although I have seen comments that the later - more powerful - 57's are quite good with the sleeper trains over the gradients in Devon and Cornwall). The higher gearing (and lower capacity electrical equipment) of the 66's versus 59's limits their maximum tractive effort in comparison, but if the problem is lack of adhesion (i.e. wheelslip) then surely this must be essentially a mechanical problem - truck design, weight distribution etc. ? Computerised wheelslip control helps to get the most out of what adhesion is available, but it won't "make a silk purse out of a sow's ear". Tony
QUOTE: Originally posted by Murphy Siding From a non-mechanical mind: Couldn't the Class 66's be upgraded with new anti wheelslip technology?
QUOTE: Originally posted by beaulieu Ok, what I am going to talk about is based upon the modern US diesels type EMD SD70s, GE Dash9s, and especially their AC traction counterparts. I don't know if the same applies to NA export locomotives as this is optional according to customer desires. Since, except for Amtrak, North American Railroads are oriented towards bulk or heavy haul transportation, the manufacutrers are offering the current microprocessor equipped locomotives with the control systems set up to produce a fixed amount of tractive effort for each throttle position rather than a fixed amount of horsepower. With this system the Engineer (Driver) does not have direct control of diesel engine speed, rather he sets a target and the locomotive control computer system attempts to find the most effiecient combination engine power output, Traction Generator Field Strength, and Traction Motor effort, to produce the desired results. This results in what was formerly a wheelslip control system becoming instead a portion of the of the Traction Management System. Instead of just being a system to stop a spinning wheel by reducing power it will transfer the power from the slipping wheel to the other wheels in an attempt to maintain total locomotive tractive effort, also since the first wheel to spin is most commonly the lead axle the systems will typical apply slightly less power to that axle to prevent problems. Further with both EMD and GE now using creeping traction control both companies have the systems setup to run the lead axle run at a slightly higher creep rate to "dress" the rail surface. With 3-phase AC traction motors the system works even better with more precise control of motor speed. With regard to Class 66 versus Class 59 wheelslip, the Class 66 should have less problems with weight transfer and similar mechanical problems due to lower motor torque until the Class 66 reaches its minimum continuous rated speed, which since the power available for traction is the same will be a higher speed than for the Class 59. BTW do you have the gear ratio for the various subclasses of Class 59s? Somewhere I read that there was no difference between the Class 59/2s and the earlier subclass inspite of the fact that they are rated at 75 mph versus 65 mph. for the earlier subclasses. Reportedly it is just where the overspeed is set.
QUOTE: [i]Originally posted by owlsroost[ Thanks for the info Beaulieu. From the information I have, there is no difference between the Class 59/2s and the earlier subclass in tractive effort - just allowed top speed, so I presume the gearing is the same (but I don't have a definitive answer). Do modern DC-drive EMD locomotives have individual power control to each axle (for wheelslip control) ? - I thought the class 60's were relatively unusual in having DC-drives with separate excitation for each motor. Out of interest, do GE and EMD locomotives with AC-drives have per-axle or per-truck invertors ? - I read somewhere that one manufacturer uses one invertor per truck, the other one per axle. (apologies for getting a bit techy - I design (non-railway) electronics for a living, and hence have an interest in the engineering side of railways). Tony (Off to Canada for 2 weeks in a few hours - hope to get in a bit of railfanning along the way - so Happy New Year to everyone!)
QUOTE: Originally posted by Simon Reed No work for me until Friday 6th, but to make up for that I've just got myself out of bed after a delightful bout of food poisoning! A question maybe best answered by Beaulieu. I've read somewhere recently (don't recall where) that SP had some U25B's re-engined by Sulzer in the 1970's. Actually it's three questions:- 1 - Were these the standard 12LDA28 units as applied to classes 44-47 in the UK? 2 - What was the outcome of the experiment? Obviously Sulzer never became a major player in the US Railroad market but are we talking failure or abject failure? 3 - Why? I know that the U-Boats never scored highly on the reliabilty stakes but re-engining a batch with an untried product (in the US) seems a little drastic.
QUOTE: Originally posted by Simon Reed Just read Beaulieus' comments. I forgot about LNER 4496, ("Dwight D Eisenhower") which he mentions. If you're including preservation SR 926 "Repton" and SR (ex LSWR) M7 class 53 were also preserved in the US for a while. Both have been repatriated and "Repton" has been a regular - and very loud - performer on one of my local preserved railways, the North Yorkshire Moors. In Canada are LNER 4489 "Dominion of Canada" and SR (ex LBSCR) "Terrier class 654 "Waddon." These are all steam locomotives, and I've just thought of a diesel! BRE-Leyland RE004, a prototype RDC, went to the US as a demonstrator in the 80's although I can't remember where. Did the prototype Deltic ever go to Canada? Any offers before I have to look it up?
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