Quentin
Originally posted by Overmod . It should be remembered that the effectiveness of conventional DB tapers off with speed, and often can't be used below a minimum speed. For example, it's possible in theory to fiddle with the motor fields to allow dynamic to work down to relatively low speeds, but this adds complexity and possible points of failure to the design. quote] In older diesels, the effectiveness ( or lack thereof, in certain situations) of dynamics below a certain speed would be more pronounced, especially in mountainous areas.... Conrail's SD40-2 were fitted with what was called 'extended range dynamic braking' which allowed the dynamic braking to be effective at lower speeds than standard dynamics....Norfolk Southern still uses ex-Conrail SD40-2's in helper service over Horseshoe Curve, and the helpers are also used on the downgrades for dynamic braking....The extended range comes in handy here, especially when trains start descending the east slope out of Gallitzin down track one, otherwise known as 'the slide' which has a 10 or 12 mph maximum downgrade speed limit....I don't know how modern dynamics on SD70's and GE Dash Nines equate to the older dynamics, are they equal to older extended range dynamics, or are the older extended range more effective, maybe someone could answer that part of it....Dave Williams http://groups.yahoo.com/group/nsaltoonajohnstown David J. Williams http://groups.yahoo.com/group/nsaltoonajohnstown Reply Overmod Member sinceSeptember 2003 21,398 posts Posted by Overmod on Sunday, November 28, 2004 6:36 PM The Jacobs Compression Brake (which I believe was actually 'invented' by Clessie Cummins) is specifically designed for direct-drive diesel engines -- it uses the considerable compression of the engine to resist rotation of the driveline, and anything that allows 'slip' in that driveline... for example, a non-locked torque converter... will degrade the available brake performance. My understanding of the brake was that the hydraulics didn't hold the exhaust valve closed, but rather opened it late in the compression stroke. At the same time, the fuel injection to the cylinder concerned was effectively cut off. Note that the compression heat keeps the cylinder in question 'hot' so the engine will promptly fire when the brake is disengaged and fuel injection is resumed. There would be little point in putting a compression brake on a railroad locomotive equipped with a Voith transmission, when the transmission itself is tremendously more effective -- and much quieter, too -- as a method of braking. The comparatively slow engine maximum speeds permitted on locomotive diesels might restrict the effective braking effort too, I'd think. Theoretically, it would be possible to brake a K-M diesel-hydraulic by engaging the reverse, then throttling up the engine and engaging (by filling, IIRC) one of the converters. The drawback here is the speed (slow) with which the mechanical reverse engagement on each truck was accomplished, and the need to get everything done and locked before applying power (this is also the reason why switching with a K-M was not a particularly desirable task -- and you thought slow-loading diesel electrics were a problem!) -- not to mention that the reverse engagement might have to be done with the unit stationary... no synchromesh! The DH643s also had Voith transmissions, and would have been poor contenders for compression brakes. Perhaps someone has distinctive knowledge of 'dynamic brake' operation on these locomotives. Reply mvlandsw Member sinceDecember 2001 1,178 posts Posted by mvlandsw on Monday, November 29, 2004 12:21 AM QUOTE: Originally posted by dwil89 Originally posted by Overmod . It should be remembered that the effectiveness of conventional DB tapers off with speed, and often can't be used below a minimum speed. For example, it's possible in theory to fiddle with the motor fields to allow dynamic to work down to relatively low speeds, but this adds complexity and possible points of failure to the design. quote] In older diesels, the effectiveness ( or lack thereof, in certain situations) of dynamics below a certain speed would be more pronounced, especially in mountainous areas.... Conrail's SD40-2 were fitted with what was called 'extended range dynamic braking' which allowed the dynamic braking to be effective at lower speeds than standard dynamics....Norfolk Southern still uses ex-Conrail SD40-2's in helper service over Horseshoe Curve, and the helpers are also used on the downgrades for dynamic braking....The extended range comes in handy here, especially when trains start descending the east slope out of Gallitzin down track one, otherwise known as 'the slide' which has a 10 or 12 mph maximum downgrade speed limit....I don't know how modern dynamics on SD70's and GE Dash Nines equate to the older dynamics, are they equal to older extended range dynamics, or are the older extended range more effective, maybe someone could answer that part of it....Dave Williams http://groups.yahoo.com/group/nsaltoonajohnstown The newer engines have extended range dynamic brakes that are much more effective than those of the SD40-2's. The dynamics on the AC units are effective almost to a stop. Reply Mookie Member sinceJune 2001 From: US 13,488 posts Posted by Mookie on Monday, November 29, 2004 7:18 AM Well, I am really in over my head here - but that never slowed me down before! When you come into a town and see a sign that says something to the affect that you can't use your Jake Brake (because of the noise, I assume) - is it safe to not use the Jake Brake? She who has no signature! cinscocom-tmw Reply william6 Member sinceDecember 2001 From: Southern Iowa, near BNSF double track mainline 111 posts Posted by william6 on Monday, November 29, 2004 8:34 AM Hi mookie, Of course it's safe not to use the "jake brake"..as a driver, you'd just better have your truck under control so that you don't have to use it. Moreover, some truck engines don't even have a jake brake...it's an option, or at least was a few years back when I drove a truck...didn't even have one on my truck...not a good truck to drive in the mountains!!!... 1st train ride was at 18 months old...and still riding the rails! Reply Modelcar Member sinceFebruary 2002 From: Muncie, Indiana...Orig. from Pennsylvania 13,456 posts Posted by Modelcar on Monday, November 29, 2004 8:42 AM ...Jen, trucks operated for years and years without a Jake Brake so a driver simply drives his rig concerning using the regular truck air brakes as he would have back when he didn't have it. Air brakes...{the normal service brakes on large trucks}, are perfectly capable of slowing and stopping a rig as it is driven in an acceptable manner. The Jake Brake is simply using an alternative method of scrubbing off speed without using those service brakes and wearing the brake lining and drums, etc.....The Jake Brake is so constructed that it uses the engine compression in a designed manner to do that work. But they really do make an annoying noise. Quentin Reply Mookie Member sinceJune 2001 From: US 13,488 posts Posted by Mookie on Monday, November 29, 2004 9:06 AM Well, that was pretty simple. Thank you! She who has no signature! cinscocom-tmw Reply dwil89 Member sinceJanuary 2004 From: NY 913 posts Posted by dwil89 on Monday, November 29, 2004 9:34 AM QUOTE: Originally posted by Modelcar ...Jen, trucks operated for years and years without a Jake Brake so a driver simply drives his rig concerning using the regular truck air brakes as he would have back when he didn't have it. Air brakes...{the normal service brakes on large trucks}, are perfectly capable of slowing and stopping a rig as it is driven in an acceptable manner. The Jake Brake is simply using an alternative method of scrubbing off speed without using those service brakes and wearing the brake lining and drums, etc.....The Jake Brake is so constructed that it uses the engine compression in a designed manner to do that work. But they really do make an annoying noise. I guess the same can be said about dynamics..trains were around long before dynamics, so they had to rely on air alot more than now...Look at any old pics of trains descending a mountain grade in steam or early diesel days...the brakeshoe smoke will be much more pronounced, though I've been told that grease leaking out of older style bearings combined with heat of braking enhanced this, now, trains can use dynamics as an aid to controlling speed, as a trucker uses a jake brake..... However, I have passed through a few communities in hilly Western Pennsylvania, where communities post signs.. No Jake braking... This is usually at the end of the grade where some truckers don't shut them off, and you would have at one time heard jakes at every stoplight and stopsign in town. Dave Williams http://groups.yahoo.com/group/nsaltoonajohnstown David J. Williams http://groups.yahoo.com/group/nsaltoonajohnstown Reply CSSHEGEWISCH Member sinceMarch 2016 From: Burbank IL (near Clearing) 13,485 posts Posted by CSSHEGEWISCH on Monday, November 29, 2004 10:06 AM Dynamic braking, while primarily used in mountain railroading, also has found some use for controlling speed in the flatlands. Some operating timetables would allow intermodal trains a speed limit of 70 MPH provided that the train could be controlled to that speed without use of the air brake, meaning by use of the dynamic brake. I'm not sure if this provision is still in use. In Illinois, I've noticed several signs posted at the top of short downgrades stating "Engine Braking Prohibited". I've often wondered if this is creating a safety hazard even though the grade is short. The daily commute is part of everyday life but I get two rides a day out of it. Paul Reply Rodney Beck Member sinceMarch 2004 From: west central Illinois 417 posts Posted by Rodney Beck on Monday, November 29, 2004 10:47 AM Hi group my name is Rodney and I am a student engineer with the BNSF we are taught to us dynamic braking as opposed to the use of air for fuel conservation when we are running, for the most part dynamics work quite fine and are able to hold the train, but as stated above they fade when the speed drops below their holding point then we use the trains automatic brake to futher control speed to a stop. As for the use of air we the engineer gets called in front of the road foreman of engines when ever we stretch brake i.e. using air above throttle notch 4. Rodney Beck Student engineer BNSF Reply Overmod Member sinceSeptember 2003 21,398 posts Posted by Overmod on Monday, November 29, 2004 10:47 AM My guess is that "Engine Braking Prohibited" would refer to the use of the locomotive independent brake -- some engineers might be tempted to trim any acceleration of the part of the train on the short downgrade with the independent, not using the main air brake, and either overheat tires or cause odd slack runins as a result. I wonder whether the extended load-up time of dynamics might also be a factor: if the dynamics don't activate as "promptly" as expected, the head end of the train might be near or in fact past the end of the grade when the dynamic resistance comes up -- this would lead both to a nominally increased train speed (and probably some stretched slack at the head end) followed by more severe run-in of the slack as the dynamics engaged. Comments from wiser heads on these points will be much appreciated. Reply dwil89 Member sinceJanuary 2004 From: NY 913 posts Posted by dwil89 on Monday, November 29, 2004 10:55 AM QUOTE: Originally posted by Overmod My guess is that "Engine Braking Prohibited" would refer to the use of the locomotive independent brake -- some engineers might be tempted to trim any acceleration of the part of the train on the short downgrade with the independent, not using the main air brake, and either overheat tires or cause odd slack runins as a result. I wonder whether the extended load-up time of dynamics might also be a factor: if the dynamics don't activate as "promptly" as expected, the head end of the train might be near or in fact past the end of the grade when the dynamic resistance comes up -- this would lead both to a nominally increased train speed (and probably some stretched slack at the head end) followed by more severe run-in of the slack as the dynamics engaged. Comments from wiser heads on these points will be much appreciated. I interpreted the" No engine braking "comment to refer to jake braking for trucks on a grade.........Dave Williams David J. Williams http://groups.yahoo.com/group/nsaltoonajohnstown Reply Randy Stahl Member sinceJune 2004 From: roundhouse 2,747 posts Posted by Randy Stahl on Monday, November 29, 2004 11:23 AM QUOTE: Originally posted by Rodney Beck Hi group my name is Rodney and I am a student engineer with the BNSF we are taught to us dynamic braking as opposed to the use of air for fuel conservation when we are running, for the most part dynamics work quite fine and are able to hold the train, but as stated above they fade when the speed drops below their holding point then we use the trains automatic brake to futher control speed to a stop. As for the use of air we the engineer gets called in front of the road foreman of engines when ever we stretch brake i.e. using air above throttle notch 4. Rodney Beck Student engineer BNSF Here is the real reason for dynamic brakes Randy Reply Junctionfan Member sinceFebruary 2004 From: St.Catharines, Ontario 3,770 posts Posted by Junctionfan on Monday, November 29, 2004 12:13 PM Are do you reduce a train's speed from 50mph to 35mph without slaming on the brakes. Having difficult time on my simulation controlling a damn F-40. Any suggestions please......... Andrew Reply Modelcar Member sinceFebruary 2002 From: Muncie, Indiana...Orig. from Pennsylvania 13,456 posts Posted by Modelcar on Monday, November 29, 2004 12:15 PM ...Dave: speaking of western Pennsylvania {hilly}, areas...Have you ever noticed the truck run-away-ramp on the downgrade of the western side of Laural Hill Mountain {Rt. 30}, about a mile before entering Laughtintown... The Jake Brake option for sure has improved safety of large rigs decending that series of down grades...some as steep as 11%...which is rather steep. The Company I worked for in that area many years ago tested brakes on those hills. Our test station was in Jennerstown, Pa. {Several test stations were located there for years}. Believe at least one still is. Quentin Reply dwil89 Member sinceJanuary 2004 From: NY 913 posts Posted by dwil89 on Monday, November 29, 2004 12:19 PM QUOTE: Originally posted by Modelcar ...Dave: speaking of western Pennsylvania {hilly}, areas...Have you ever noticed the truck run-away-ramp on the downgrade of the western side of Laural Hill Mountain {Rt. 30}, about a mile before entering Laughtintown... . Yup.... I know that hill...My aunt and uncle live in Laughlintown near that Boyscout camp, and the Jakebrake noise from Rte 30 is quite noticeable there as the grade is just leveling out at that location. Dave W. David J. Williams http://groups.yahoo.com/group/nsaltoonajohnstown Reply Randy Stahl Member sinceJune 2004 From: roundhouse 2,747 posts Posted by Randy Stahl on Monday, November 29, 2004 1:07 PM QUOTE: Originally posted by M.W. Hemphill ... and here I thought it was to employ electricians in the roundhouse to replace melted grids and welded-together contactors. In my experience.... I thought thats what the self load feature is for, kind of a make work switch. Ask the North Fond du lac fire dept. Randy Reply dwil89 Member sinceJanuary 2004 From: NY 913 posts Posted by dwil89 on Monday, November 29, 2004 10:51 PM Talking about Jake brakes, I see that they are becoming more prevalent in Buses too. The latest MCI buses have them. I saw one today in my local area....I think it had a Cat engine in it,,,sounded nothing like the Detroit Diesels the older ones had....I went to the MCI website and found that 12.7 liter Detroits are standard with a Cat engine optional...Jake brakes are available on them too! And the 12.7 liter puts out 400 HP! The old GMC Coaches I used to ride as a kid on summer camp day trips certainly did not have anywhere close to that HP.....You could eat lunch and take a nap, it seemed ,in the time it took the older buses to get out of a toll booth and up to highway speed....Dave W David J. Williams http://groups.yahoo.com/group/nsaltoonajohnstown Reply GMS-AU Member sinceMay 2004 From: Australia 56 posts Posted by GMS-AU on Sunday, December 5, 2004 7:57 AM Dave and others Jacobs Engine Brakes are available on all three major American makes - Cummins, Cat and Detroit, with Cummins producing its own version called C-Brake. Detroit is not owned by GM anymore and the current 60 series 4 stroke engine actually appeared about the same time as the 60 series loco's, does anybody know if there is a connection there? As stated they work directly on engine compression and claims of up 75-80% of engine power can be used to retard the engine. The 12.7 litre Detroit can produce up to 500 hp so its braking effort could be at least 400 hp. Japanese and European engines generally use exhaust brakes, which is essentially blocking the exhaust of an engine and causing it not to induct and depower. This is not as effective as an actual engine retard like a Jacobs ( Jake ) Brake but is still quite capable of holding a truck if the right gear is used. It is available on most Japanese diesel trucks right down to 1.5 tonne versions and is a handy device and nowhere near as noisy as on much larger trucks. The only problems I have found ( I drive trucks for a living ) is with engine or exhaust brakes in off road or unsealed roads or wet roads they can cause axle tramping and the rear can skip if unladen. This is also the case with hydraulic automatics ( Allison's etc ) and their retarder system. The normal foot brakes then are used to help control the truck. Does this happen with trains as well. If dynamics are applied without air can the loco's skip in the same fashion, essentially be pushed along like as if the brakes where locked on? G M Simpson There is no replacement for displacement! Reply arbfbe Member sinceFebruary 2002 910 posts Posted by arbfbe on Sunday, December 5, 2004 2:23 PM I believe the series number of the engine model refers to the cu in displacement of each cylinder just like the locomotive engines are. Thus the DD60 series would have 60 cu in displacement per cylinder like an EMD 645 has 645 cu in per cylinder. When the dynamic braking causes the wheels to lock up you get flat spots on the wheels. Commonly, only one or two axles will lock up. This is usually due to water, ice or oil on the rail. A quick application of traction sand usually gets everything rolling again though there will likely find the click, click, click of a hickey on the wheels. Reply 12 Join our Community! Our community is FREE to join. To participate you must either login or register for an account. Login » Register » Search the Community Newsletter Sign-Up By signing up you may also receive occasional reader surveys and special offers from Trains magazine.Please view our privacy policy More great sites from Kalmbach Media Terms Of Use | Privacy Policy | Copyright Policy
QUOTE: Originally posted by dwil89 Originally posted by Overmod . It should be remembered that the effectiveness of conventional DB tapers off with speed, and often can't be used below a minimum speed. For example, it's possible in theory to fiddle with the motor fields to allow dynamic to work down to relatively low speeds, but this adds complexity and possible points of failure to the design. quote] In older diesels, the effectiveness ( or lack thereof, in certain situations) of dynamics below a certain speed would be more pronounced, especially in mountainous areas.... Conrail's SD40-2 were fitted with what was called 'extended range dynamic braking' which allowed the dynamic braking to be effective at lower speeds than standard dynamics....Norfolk Southern still uses ex-Conrail SD40-2's in helper service over Horseshoe Curve, and the helpers are also used on the downgrades for dynamic braking....The extended range comes in handy here, especially when trains start descending the east slope out of Gallitzin down track one, otherwise known as 'the slide' which has a 10 or 12 mph maximum downgrade speed limit....I don't know how modern dynamics on SD70's and GE Dash Nines equate to the older dynamics, are they equal to older extended range dynamics, or are the older extended range more effective, maybe someone could answer that part of it....Dave Williams http://groups.yahoo.com/group/nsaltoonajohnstown The newer engines have extended range dynamic brakes that are much more effective than those of the SD40-2's. The dynamics on the AC units are effective almost to a stop. Reply Mookie Member sinceJune 2001 From: US 13,488 posts Posted by Mookie on Monday, November 29, 2004 7:18 AM Well, I am really in over my head here - but that never slowed me down before! When you come into a town and see a sign that says something to the affect that you can't use your Jake Brake (because of the noise, I assume) - is it safe to not use the Jake Brake? She who has no signature! cinscocom-tmw Reply william6 Member sinceDecember 2001 From: Southern Iowa, near BNSF double track mainline 111 posts Posted by william6 on Monday, November 29, 2004 8:34 AM Hi mookie, Of course it's safe not to use the "jake brake"..as a driver, you'd just better have your truck under control so that you don't have to use it. Moreover, some truck engines don't even have a jake brake...it's an option, or at least was a few years back when I drove a truck...didn't even have one on my truck...not a good truck to drive in the mountains!!!... 1st train ride was at 18 months old...and still riding the rails! Reply Modelcar Member sinceFebruary 2002 From: Muncie, Indiana...Orig. from Pennsylvania 13,456 posts Posted by Modelcar on Monday, November 29, 2004 8:42 AM ...Jen, trucks operated for years and years without a Jake Brake so a driver simply drives his rig concerning using the regular truck air brakes as he would have back when he didn't have it. Air brakes...{the normal service brakes on large trucks}, are perfectly capable of slowing and stopping a rig as it is driven in an acceptable manner. The Jake Brake is simply using an alternative method of scrubbing off speed without using those service brakes and wearing the brake lining and drums, etc.....The Jake Brake is so constructed that it uses the engine compression in a designed manner to do that work. But they really do make an annoying noise. Quentin Reply Mookie Member sinceJune 2001 From: US 13,488 posts Posted by Mookie on Monday, November 29, 2004 9:06 AM Well, that was pretty simple. Thank you! She who has no signature! cinscocom-tmw Reply dwil89 Member sinceJanuary 2004 From: NY 913 posts Posted by dwil89 on Monday, November 29, 2004 9:34 AM QUOTE: Originally posted by Modelcar ...Jen, trucks operated for years and years without a Jake Brake so a driver simply drives his rig concerning using the regular truck air brakes as he would have back when he didn't have it. Air brakes...{the normal service brakes on large trucks}, are perfectly capable of slowing and stopping a rig as it is driven in an acceptable manner. The Jake Brake is simply using an alternative method of scrubbing off speed without using those service brakes and wearing the brake lining and drums, etc.....The Jake Brake is so constructed that it uses the engine compression in a designed manner to do that work. But they really do make an annoying noise. I guess the same can be said about dynamics..trains were around long before dynamics, so they had to rely on air alot more than now...Look at any old pics of trains descending a mountain grade in steam or early diesel days...the brakeshoe smoke will be much more pronounced, though I've been told that grease leaking out of older style bearings combined with heat of braking enhanced this, now, trains can use dynamics as an aid to controlling speed, as a trucker uses a jake brake..... However, I have passed through a few communities in hilly Western Pennsylvania, where communities post signs.. No Jake braking... This is usually at the end of the grade where some truckers don't shut them off, and you would have at one time heard jakes at every stoplight and stopsign in town. Dave Williams http://groups.yahoo.com/group/nsaltoonajohnstown David J. Williams http://groups.yahoo.com/group/nsaltoonajohnstown Reply CSSHEGEWISCH Member sinceMarch 2016 From: Burbank IL (near Clearing) 13,485 posts Posted by CSSHEGEWISCH on Monday, November 29, 2004 10:06 AM Dynamic braking, while primarily used in mountain railroading, also has found some use for controlling speed in the flatlands. Some operating timetables would allow intermodal trains a speed limit of 70 MPH provided that the train could be controlled to that speed without use of the air brake, meaning by use of the dynamic brake. I'm not sure if this provision is still in use. In Illinois, I've noticed several signs posted at the top of short downgrades stating "Engine Braking Prohibited". I've often wondered if this is creating a safety hazard even though the grade is short. The daily commute is part of everyday life but I get two rides a day out of it. Paul Reply Rodney Beck Member sinceMarch 2004 From: west central Illinois 417 posts Posted by Rodney Beck on Monday, November 29, 2004 10:47 AM Hi group my name is Rodney and I am a student engineer with the BNSF we are taught to us dynamic braking as opposed to the use of air for fuel conservation when we are running, for the most part dynamics work quite fine and are able to hold the train, but as stated above they fade when the speed drops below their holding point then we use the trains automatic brake to futher control speed to a stop. As for the use of air we the engineer gets called in front of the road foreman of engines when ever we stretch brake i.e. using air above throttle notch 4. Rodney Beck Student engineer BNSF Reply Overmod Member sinceSeptember 2003 21,398 posts Posted by Overmod on Monday, November 29, 2004 10:47 AM My guess is that "Engine Braking Prohibited" would refer to the use of the locomotive independent brake -- some engineers might be tempted to trim any acceleration of the part of the train on the short downgrade with the independent, not using the main air brake, and either overheat tires or cause odd slack runins as a result. I wonder whether the extended load-up time of dynamics might also be a factor: if the dynamics don't activate as "promptly" as expected, the head end of the train might be near or in fact past the end of the grade when the dynamic resistance comes up -- this would lead both to a nominally increased train speed (and probably some stretched slack at the head end) followed by more severe run-in of the slack as the dynamics engaged. Comments from wiser heads on these points will be much appreciated. Reply dwil89 Member sinceJanuary 2004 From: NY 913 posts Posted by dwil89 on Monday, November 29, 2004 10:55 AM QUOTE: Originally posted by Overmod My guess is that "Engine Braking Prohibited" would refer to the use of the locomotive independent brake -- some engineers might be tempted to trim any acceleration of the part of the train on the short downgrade with the independent, not using the main air brake, and either overheat tires or cause odd slack runins as a result. I wonder whether the extended load-up time of dynamics might also be a factor: if the dynamics don't activate as "promptly" as expected, the head end of the train might be near or in fact past the end of the grade when the dynamic resistance comes up -- this would lead both to a nominally increased train speed (and probably some stretched slack at the head end) followed by more severe run-in of the slack as the dynamics engaged. Comments from wiser heads on these points will be much appreciated. I interpreted the" No engine braking "comment to refer to jake braking for trucks on a grade.........Dave Williams David J. Williams http://groups.yahoo.com/group/nsaltoonajohnstown Reply Randy Stahl Member sinceJune 2004 From: roundhouse 2,747 posts Posted by Randy Stahl on Monday, November 29, 2004 11:23 AM QUOTE: Originally posted by Rodney Beck Hi group my name is Rodney and I am a student engineer with the BNSF we are taught to us dynamic braking as opposed to the use of air for fuel conservation when we are running, for the most part dynamics work quite fine and are able to hold the train, but as stated above they fade when the speed drops below their holding point then we use the trains automatic brake to futher control speed to a stop. As for the use of air we the engineer gets called in front of the road foreman of engines when ever we stretch brake i.e. using air above throttle notch 4. Rodney Beck Student engineer BNSF Here is the real reason for dynamic brakes Randy Reply Junctionfan Member sinceFebruary 2004 From: St.Catharines, Ontario 3,770 posts Posted by Junctionfan on Monday, November 29, 2004 12:13 PM Are do you reduce a train's speed from 50mph to 35mph without slaming on the brakes. Having difficult time on my simulation controlling a damn F-40. Any suggestions please......... Andrew Reply Modelcar Member sinceFebruary 2002 From: Muncie, Indiana...Orig. from Pennsylvania 13,456 posts Posted by Modelcar on Monday, November 29, 2004 12:15 PM ...Dave: speaking of western Pennsylvania {hilly}, areas...Have you ever noticed the truck run-away-ramp on the downgrade of the western side of Laural Hill Mountain {Rt. 30}, about a mile before entering Laughtintown... The Jake Brake option for sure has improved safety of large rigs decending that series of down grades...some as steep as 11%...which is rather steep. The Company I worked for in that area many years ago tested brakes on those hills. Our test station was in Jennerstown, Pa. {Several test stations were located there for years}. Believe at least one still is. Quentin Reply dwil89 Member sinceJanuary 2004 From: NY 913 posts Posted by dwil89 on Monday, November 29, 2004 12:19 PM QUOTE: Originally posted by Modelcar ...Dave: speaking of western Pennsylvania {hilly}, areas...Have you ever noticed the truck run-away-ramp on the downgrade of the western side of Laural Hill Mountain {Rt. 30}, about a mile before entering Laughtintown... . Yup.... I know that hill...My aunt and uncle live in Laughlintown near that Boyscout camp, and the Jakebrake noise from Rte 30 is quite noticeable there as the grade is just leveling out at that location. Dave W. David J. Williams http://groups.yahoo.com/group/nsaltoonajohnstown Reply Randy Stahl Member sinceJune 2004 From: roundhouse 2,747 posts Posted by Randy Stahl on Monday, November 29, 2004 1:07 PM QUOTE: Originally posted by M.W. Hemphill ... and here I thought it was to employ electricians in the roundhouse to replace melted grids and welded-together contactors. In my experience.... I thought thats what the self load feature is for, kind of a make work switch. Ask the North Fond du lac fire dept. Randy Reply dwil89 Member sinceJanuary 2004 From: NY 913 posts Posted by dwil89 on Monday, November 29, 2004 10:51 PM Talking about Jake brakes, I see that they are becoming more prevalent in Buses too. The latest MCI buses have them. I saw one today in my local area....I think it had a Cat engine in it,,,sounded nothing like the Detroit Diesels the older ones had....I went to the MCI website and found that 12.7 liter Detroits are standard with a Cat engine optional...Jake brakes are available on them too! And the 12.7 liter puts out 400 HP! The old GMC Coaches I used to ride as a kid on summer camp day trips certainly did not have anywhere close to that HP.....You could eat lunch and take a nap, it seemed ,in the time it took the older buses to get out of a toll booth and up to highway speed....Dave W David J. Williams http://groups.yahoo.com/group/nsaltoonajohnstown Reply GMS-AU Member sinceMay 2004 From: Australia 56 posts Posted by GMS-AU on Sunday, December 5, 2004 7:57 AM Dave and others Jacobs Engine Brakes are available on all three major American makes - Cummins, Cat and Detroit, with Cummins producing its own version called C-Brake. Detroit is not owned by GM anymore and the current 60 series 4 stroke engine actually appeared about the same time as the 60 series loco's, does anybody know if there is a connection there? As stated they work directly on engine compression and claims of up 75-80% of engine power can be used to retard the engine. The 12.7 litre Detroit can produce up to 500 hp so its braking effort could be at least 400 hp. Japanese and European engines generally use exhaust brakes, which is essentially blocking the exhaust of an engine and causing it not to induct and depower. This is not as effective as an actual engine retard like a Jacobs ( Jake ) Brake but is still quite capable of holding a truck if the right gear is used. It is available on most Japanese diesel trucks right down to 1.5 tonne versions and is a handy device and nowhere near as noisy as on much larger trucks. The only problems I have found ( I drive trucks for a living ) is with engine or exhaust brakes in off road or unsealed roads or wet roads they can cause axle tramping and the rear can skip if unladen. This is also the case with hydraulic automatics ( Allison's etc ) and their retarder system. The normal foot brakes then are used to help control the truck. Does this happen with trains as well. If dynamics are applied without air can the loco's skip in the same fashion, essentially be pushed along like as if the brakes where locked on? G M Simpson There is no replacement for displacement! Reply arbfbe Member sinceFebruary 2002 910 posts Posted by arbfbe on Sunday, December 5, 2004 2:23 PM I believe the series number of the engine model refers to the cu in displacement of each cylinder just like the locomotive engines are. Thus the DD60 series would have 60 cu in displacement per cylinder like an EMD 645 has 645 cu in per cylinder. When the dynamic braking causes the wheels to lock up you get flat spots on the wheels. Commonly, only one or two axles will lock up. This is usually due to water, ice or oil on the rail. A quick application of traction sand usually gets everything rolling again though there will likely find the click, click, click of a hickey on the wheels. Reply 12 Join our Community! Our community is FREE to join. To participate you must either login or register for an account. Login » Register » Search the Community Newsletter Sign-Up By signing up you may also receive occasional reader surveys and special offers from Trains magazine.Please view our privacy policy More great sites from Kalmbach Media Terms Of Use | Privacy Policy | Copyright Policy
Originally posted by Overmod . It should be remembered that the effectiveness of conventional DB tapers off with speed, and often can't be used below a minimum speed. For example, it's possible in theory to fiddle with the motor fields to allow dynamic to work down to relatively low speeds, but this adds complexity and possible points of failure to the design. quote] In older diesels, the effectiveness ( or lack thereof, in certain situations) of dynamics below a certain speed would be more pronounced, especially in mountainous areas.... Conrail's SD40-2 were fitted with what was called 'extended range dynamic braking' which allowed the dynamic braking to be effective at lower speeds than standard dynamics....Norfolk Southern still uses ex-Conrail SD40-2's in helper service over Horseshoe Curve, and the helpers are also used on the downgrades for dynamic braking....The extended range comes in handy here, especially when trains start descending the east slope out of Gallitzin down track one, otherwise known as 'the slide' which has a 10 or 12 mph maximum downgrade speed limit....I don't know how modern dynamics on SD70's and GE Dash Nines equate to the older dynamics, are they equal to older extended range dynamics, or are the older extended range more effective, maybe someone could answer that part of it....Dave Williams http://groups.yahoo.com/group/nsaltoonajohnstown
She who has no signature! cinscocom-tmw
QUOTE: Originally posted by Modelcar ...Jen, trucks operated for years and years without a Jake Brake so a driver simply drives his rig concerning using the regular truck air brakes as he would have back when he didn't have it. Air brakes...{the normal service brakes on large trucks}, are perfectly capable of slowing and stopping a rig as it is driven in an acceptable manner. The Jake Brake is simply using an alternative method of scrubbing off speed without using those service brakes and wearing the brake lining and drums, etc.....The Jake Brake is so constructed that it uses the engine compression in a designed manner to do that work. But they really do make an annoying noise.
QUOTE: Originally posted by Overmod My guess is that "Engine Braking Prohibited" would refer to the use of the locomotive independent brake -- some engineers might be tempted to trim any acceleration of the part of the train on the short downgrade with the independent, not using the main air brake, and either overheat tires or cause odd slack runins as a result. I wonder whether the extended load-up time of dynamics might also be a factor: if the dynamics don't activate as "promptly" as expected, the head end of the train might be near or in fact past the end of the grade when the dynamic resistance comes up -- this would lead both to a nominally increased train speed (and probably some stretched slack at the head end) followed by more severe run-in of the slack as the dynamics engaged. Comments from wiser heads on these points will be much appreciated.
QUOTE: Originally posted by Rodney Beck Hi group my name is Rodney and I am a student engineer with the BNSF we are taught to us dynamic braking as opposed to the use of air for fuel conservation when we are running, for the most part dynamics work quite fine and are able to hold the train, but as stated above they fade when the speed drops below their holding point then we use the trains automatic brake to futher control speed to a stop. As for the use of air we the engineer gets called in front of the road foreman of engines when ever we stretch brake i.e. using air above throttle notch 4. Rodney Beck Student engineer BNSF
QUOTE: Originally posted by Modelcar ...Dave: speaking of western Pennsylvania {hilly}, areas...Have you ever noticed the truck run-away-ramp on the downgrade of the western side of Laural Hill Mountain {Rt. 30}, about a mile before entering Laughtintown... .
QUOTE: Originally posted by M.W. Hemphill ... and here I thought it was to employ electricians in the roundhouse to replace melted grids and welded-together contactors.
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