My question pertains to curves on a double track mainline. I know that the inside track will have a smaller radius, but how can I accomplish this using the fixed Unitrack curves? I would like to keep the curves as broad as possible, like using 19" radius pieces on the curves. The only solution I can think of is to use a double track viaduct curve, but I would like the curves to be wider? Has anyone out there dealt with this? As I will be using modern equipment, how tight can the radius be without looking too unrealistic? [ 10 July 2002, 12:40: Message edited by: bnsf shaun ]
The largest doubletrack curves Kato makes is 13 3/4" and 15". Using the 19" or 28.25" will require putting short spacers in it to stretch the curve out a bit. I haven't tried to see exactly what would be needed.
Shaun, Tell me exactly what outside radius curve you want and how many degrees it will be turning. My double track switchyard turn around turns 180 deg. on a 15" radius for the outside track. The inner track uses 13 3/4 30 deg and 45 deg. radius curves to stay double track matched all the way around the 180 deg. curve. Will yours be turning 180, 90 45 or what degrees. I have lots of loose curved Kato Unitrack to play with and have many pieces of every curve from 9 to 281/4" Send me the info on the outside radius you want and the degree of the curve and I will get the track out and fit it together to determine what you need.
Shaun-I am not sure about the tighter radius curves but I have been using the 28.25" radius on both the inner and outer sides of my double track curves. If there is any doglegging, my eyes can't spot it. As far as the transition to the straight tracks, just buy the shortie track assortments or use the expandable section to bring things into allingment. John
Gary, I will be using either 19.75" (is that right?) or 28.25" going around 90 degree turns in corners. I may use 45 degree turns in scenes as well. I may also use gentle curves going through scenes so that the mainline doesn't always parallel the edge of the layout. My governing equipment will be Dash-9's, double stacks & trailers on 89-foot flats, and 85 ft auto racks, so I want them to look right going around curves. Also, how would you construct an easement with Unitrack curves? I appreciate any info you can provide. I have the Unitrack template, but I'm having trouble getting the 2 mainlines to line up on paper. Shaun
Gary, I will be using either 19.75" (is that right?) or 28.25" going around 90 degree turns in corners. I may use 45 degree turns in scenes as well. I may also use gentle curves going through scenes so that the mainline doesn't always parallel the edge of the layout. My governing equipment will be Dash-9's, double stacks & trailers on 89-foot flats, and 85 ft auto racks, so I want them to look right going around curves. Also, how would you construct an easement with Unitrack curves? I appreciate any info you can provide. I have the Unitrack template, but I'm having trouble getting the 2 mainlines to line up on paper. Shaun
Shaun, I'm laying out the track now, but I'm not sure what you mean by constructing an easement with Unitrack curves. Do you mean one track at a higher elevation, passing over another, or elevated track passing over a piece of property or just additional space between the double track? Kato crved track comes in the following radius. 28 1/4"-15 deg, 19"-15 deg, 15"-30 deg, 13 3/4"-30 & 45 deg, 12 3/8"-15 & 45 deg, 11"-15 & 45 deg, and 9 3/4"-15 & 45 deg. If you are running cars in the 89 ft. length, I would not go below 15"r curves on a main line. I'm modeling in the late 50's era, so the longest cars I have are 80 ft. passenger cars. A 15"r curve for them is too tight to consider trying to put diaphragms on them. If you plan to back your long cars trough turnouts and tight curves, particulary a Kato #4 turnout, I would suggest that you put body mount couplers on them if it is possible. My coaches that have body mount couplers on them handle much better backing up through switches and tight curves than the ones with truck mounted couplers and I'm talking about MT couplers in both cases. Gary
Gary, an easement is where there is a gentle large radius to start a curve from a straight track that gets a smaller and smaller radius until you get down to the radius you want on the curve. Like to have a 15" radius 90 degree curve from straight track A to straight track B, you would start at the end of A with say, a 4" length of 30" radius track, then with 5" of 28", then 6" of 24", then on down until you came to the 15" radius, which would probably only be a length to make 45 degrees of true radius, then it would start getting sections of larger radius untill you ended up at the end of straight track B again, see? A quick illustration of how it works: Pull out about 4 feet of a carpenter's steel tape measure and lock it in place. (The loop formed is the true radius you want, the two legs leading to it, are easements.) Now pull the end back down to the case so you will have a loop at about the 2 foot mark. Now go to a table, and lay the end of the tape down flat with the numbers up on the table and hold it there with your left hand, and turn the tape case flat with the numbers up, with your right hand. Keep the numbers on the inside of the loop. It should look like you could run a toy car from the case fast along the tape, and it would "bank" into the loop like at a race track and return to the end of the tape. You get the point? Easements are neccessary so high speed trains wont tip over when hitting a sudden curve because momentum keeps the engine wanting to go straight ahead, while the track pulls the wheels sideways out from under the engine. The easement gently gives the engine time to start changing direction. That is also why straight track is level, and curved track is tilted in board toward the curve's center point, we call elevation. The outside rail is set higher gradually as you enter the curve, then gradually lowered again to level as the curve is completed. It keeps the center of gravity in the middle of the rails, the same as when a boat or airplane "banks" into a curve, see? Its a good question Gary! [ 11 July 2002, 21:50: Message edited by: watash ]
Watash's description of an easement will only get you an approximation. Actually there are no sections of the same radius, rather the radius constantly reduces from the tangent (where it is an infinite radius) until it is the curve radius. You need flex track to do this, can't do it with sectional. It's a nit, I know! [ 11 July 2002, 21:41: Message edited by: Bill Kamery ]
Shaun, I've been playing with curved track pieces for about 3 hrs now and have come to the following conclusions. Using Kato Unitrack, you cannot match a 19" or 28 1/4" 90 deg. radius curve on the inside of the curve if you want to double track it. However, the solution is simply to make the outer double track radius larger by adding a number of 1 1/8th " straight track pieces. On the 28 1/4" radius double track curve, this is accomplished by adding FOUR-1 1/8" straight track pieces to the 6 outside 28 1/4" curves on the double track. On the 19" radius double track curve, this is accomplished by adding THREE-1 1/8" straight track pieces to the the 6 outside 19" curves on the double track. On the 28 1/4" radius curve, the four short pieces of straight track are added to the outside 6 - 28 1/4" curved pieces in this order: 281/4...281/4...1 1/8...28 1/4...1 1/8...28 1/4...1 1/8...28 1/4...1 1/8...28 1/4. On the 19" radius curve, the three short straight pieces are added to the outside 6 - 19" curved pieces in this order: 19...1 1/8...19...19...1 1/8...19...1 1/8...19...19. The short pieces come in a box consisting of 8-1 1/8"( 29mm) pieces and two 1 3/4"(45.5mm)pieces. the Kato cat. number for this box is Track Assortment Set 20-090. Buy a lot of these boxes if you plan on doing a lot of large radius curve double tracking. On 15' radius curve double tracking, the solution is different. This seems to be the best looking solution for double tracking 28 1/4" and 19" radius curves, using only Kato Unitrack, that I could come up with. I also was planning to have 19" and 28 1/4" radius curves in the corners on the rest of my layout and this is the system I will use. Gary
Thanks fellows, now I understand what Shaun was asking about. To me, an easement only has something to do with property. In Calgary Canada, my brother who did the CPR Special Projects Engineering Dept. design on all the double tracking leading up to The Rogers Pass Spiral Tunnel, refered to what you described, as super elevating the curves. Actually I have tried that with wide radius curved sections of Kato Unitrack and it is possible, but I only did it on a non diminishing curve. It is a real fiddle supporting the track at the unijoiners to keep the rails level and I don't think I'll bother to do it anymore as I don't have any bullet trains to run around curves. Thanks for explaining your definition of easement.
Gary, thank you for your time and effort in finding a solution to my problem. Right now my Unitrack is in a box in my apartment on Guam (I'm in Japan right now), otherwise I would be able to fiddle with it. I've tried drawing things out with the Unitrack template, but nothing would come out. I would much rather use Unitrack than deal with laying down cork, track, soldering, etc. as I am not a mechanically inclined person. Once I return stateside in November, I will be constructing a layout in my Dad and Stepmom's basement, setting of the layout in one of 3 places, Pacific NW, southern california, or midwest. The hard part is deciding which!
Shaun, It was my pleasure to be of assistance to you and it also gave ME the answer to the same problem I would have had when I got to that point in finshing my layout down the road. I'm with you on the bit about laying down cork, flex track and soldering, that's why I'll stick to Kato Unitrack even if I am mechanically trained. Anytime you have a question about Kato Unitrack send me an email off trainboard if you wish, I'll be happy to help if I can. Gary
I have a double track curve in Kato-Unitrack. On the outer track I use: 1 section of 15° 28 1/4" radius 1 section of 15° 19" radius 4 sections of 30° 15" radius 1 section of 15° 19" radius 1 section of 15° 28 1/4" radius On the inner track: 1 section of 15° 28 1/4" radius 1 section of 15° 19" radius 4 sections of 30° 13 3/4" radius 1 section of 15° 19" radius 1 section of 15° 28 1/4" radius Inner and outer straight can be fitted with the small track pieces. It is not perfect but my 85' passenger Budd cars flow trough these eased curves witn no problem. Paul
FOR COMPLETELY NUTS, no pun intended. You didn't say what degree of curve your description represented, so I will llayout your interesting description of the various pieces of curved Kato Unitrack track for a double track curve and see what evolves. Both the 28 1/4" r and the 19" r 90 deg. double track turns I described to Shaun, match perfectly all the way around the turn. Would you like to see a picture? You say yours is not perfect, what seems to be the problem? The curve I built for Shaun is not an easement ( using a definition described to me). I won't know what yours is until I lay it out. I find it much simpler to lay a double track curve using Kato Unitrack, if I modify the outside track and keep the inner curve constant, that is of course, if I'm not laying a double track "EASEMENT". I don't really think that there is a correct and a wrong way to lay down Kato Unitrack in these instances, because of the multitude of pieces available. I think it's simply a case of what WORKS BEST FOR YOU with the pieces you have available and LOOKS BEST, for the individual involved.
Hey Garry, If you make the sum of the degrees you will arrive at a curve of 180°. And this eased curve means a transition from straight to sharp and from sharp to straight. Hope you understand what I try to explain. Paul
Yes Paul , I know where the track goes on this one. It is an good even spaced double track curve that works and looks like half of a yellow sign that makes us hungry for hamburgers. On the outside track of the180 deg.turn, you made the turnaround in 33" outside to outside of the Kato roadbed. For the inner track you made it in 29". That's how it looks with my Kato Unitrack pieces. I prefer to stay away from 180 deg. curves with a kink at the apex of the arc and prefer to use constant radius curves all the way around. That is a mistake I see people make using flex track to make short radius 180 deg. curves, a tight radius at the apex, but to each his own . Shaun was only doing a 90 deg. turn in about a 30" width straight to straight and wanted to use 28 1/4 all the way around and probably has room to go bigger on the ouitside track. The "transition- easement" thingme guys will all be happy to know that I also have a thingme curve of 195 deg. going into my swyd, that is because I had to do it in 26 3/4" width outside to outside of the kato track roadbed. It is part of what starts out as a double track 180 deg. turn and the outside is 15"r all he way around. At the end of the 180 turn, the inner track curves in, away from the outside track. Get the picture? The inner curve is comprised of 1-13 3/4-45, 2-13 3/4-30, 2- 12 3/8-45. That is as tight as I want to go with a 10 car train full of 80ft. passenger cars, even if they are going into the yard. The outside double track is 15"r all the way around as I had to do it in 31". Your double track turn looks very nice and evenly spaced, but I prefer a constant radius curve all the way around if possible. I have a number of 4-8-4 steamers and they don't like small radius curved track at the apex of a 180 deg. turn. No problem though, if you are only using box cars with motors in them. Thanks for the imput.
