I have two Athearn rdcs with rubber band drives. Haven't run them for years but I did reduce the rubber bands to one per car. Have to say it sounded and started like a real rdc before it got up to 200mph.
speedybeespeedybee wrote the following post 17 days ago: John-NYBW If an unpowered car is towed behind it, the warranty is voided. If I'm reading the warranty correctly, I can't even couple it with a powered RDC from another manufacturer. It can only be coupled with other Rapido RDCs. It further states that the RDC is equipped with a detector that can determine if another car is towed by the RDC. I suspect this is Rapido humour and not actual fact. They throw some bizarre stuff in their manuals sometimes.
I suspect this is Rapido humour and not actual fact. They throw some bizarre stuff in their manuals sometimes.
The joke you are missing is that this mimics the actual RDC warranty. The prototype RDC warranty prohibited towing other cars with the RDC. You might say Rapido included a "prototype" warranty.
Dave H. Painted side goes up. My website : wnbranch.com
Part of the speed issues with the LifeLike proto 1000 RDCs is there is a diode bridge arrangement for constant lighting with 2 additional diodes for directional lighting. The voltage drop across the bridge, which is wired in series with the motor is about 1 and 1/2 volts. This voltage then feeds light bulbs which I believe are likely 3 volt bulbs. you can remove the diode bridge , the other diodes for directional control and 3 volt bulbs. You can wire LEDs for new directional lighting.. Eliminating the diode bridge will allow another 1 and 1/2 volts to go to the motor. You should get about 10 or 15 MPH speed increase.
If this increase is not enough I think Northwest Shortline did offer a regear kit for the RDC which should help..
This diode bridge was very common back in the 1970s and 1980s ,it provided costant lighting . With 2 additional diodes and 3 volt bulbs you had directional control of diesel headlights.
Ron High
I do not know if this lighting arrangement with the newer Walthers reissue of the LL proto RDC is wired this way.
ATLANTIC CENTRAL John-NYBW speedybee John-NYBW If an unpowered car is towed behind it, the warranty is voided. If I'm reading the warranty correctly, I can't even couple it with a powered RDC from another manufacturer. It can only be coupled with other Rapido RDCs. It further states that the RDC is equipped with a detector that can determine if another car is towed by the RDC. I suspect this is Rapido humour and not actual fact. They throw some bizarre stuff in their manuals sometimes. It that is the case, I find that inexcusable. How is the user supposed to know this is tongue in cheek. Or maybe this is their way of encouraging the user to only buy their RDCs. On the other hand, it does seem strange that they would put a car this fragile on the market. Your example of two powered Rapido RDCs is a good one. Just hitting a dirty spot on the track might cause a brief stall and if their drive trains are as fragile as their manual suggests, that would be enough to cause it to break. Whatever the actual case is, it is enough of a reason for me to never buy another Rapido product. Now that it is brought up, Jason is by all accounts the kind of person who do something like that, making fun of the original Budd warranty issues. I know everybody who follows youtube, etc, likes Jason, but I have to lean toward your view John. Not everybody is a social media follower or will "get" the inside joke. Sheldon
John-NYBW speedybee John-NYBW If an unpowered car is towed behind it, the warranty is voided. If I'm reading the warranty correctly, I can't even couple it with a powered RDC from another manufacturer. It can only be coupled with other Rapido RDCs. It further states that the RDC is equipped with a detector that can determine if another car is towed by the RDC. I suspect this is Rapido humour and not actual fact. They throw some bizarre stuff in their manuals sometimes. It that is the case, I find that inexcusable. How is the user supposed to know this is tongue in cheek. Or maybe this is their way of encouraging the user to only buy their RDCs. On the other hand, it does seem strange that they would put a car this fragile on the market. Your example of two powered Rapido RDCs is a good one. Just hitting a dirty spot on the track might cause a brief stall and if their drive trains are as fragile as their manual suggests, that would be enough to cause it to break. Whatever the actual case is, it is enough of a reason for me to never buy another Rapido product.
speedybee John-NYBW If an unpowered car is towed behind it, the warranty is voided. If I'm reading the warranty correctly, I can't even couple it with a powered RDC from another manufacturer. It can only be coupled with other Rapido RDCs. It further states that the RDC is equipped with a detector that can determine if another car is towed by the RDC. I suspect this is Rapido humour and not actual fact. They throw some bizarre stuff in their manuals sometimes.
John-NYBW If an unpowered car is towed behind it, the warranty is voided. If I'm reading the warranty correctly, I can't even couple it with a powered RDC from another manufacturer. It can only be coupled with other Rapido RDCs. It further states that the RDC is equipped with a detector that can determine if another car is towed by the RDC.
It that is the case, I find that inexcusable. How is the user supposed to know this is tongue in cheek. Or maybe this is their way of encouraging the user to only buy their RDCs.
On the other hand, it does seem strange that they would put a car this fragile on the market.
Your example of two powered Rapido RDCs is a good one. Just hitting a dirty spot on the track might cause a brief stall and if their drive trains are as fragile as their manual suggests, that would be enough to cause it to break.
Whatever the actual case is, it is enough of a reason for me to never buy another Rapido product.
Now that it is brought up, Jason is by all accounts the kind of person who do something like that, making fun of the original Budd warranty issues.
I know everybody who follows youtube, etc, likes Jason, but I have to lean toward your view John.
Not everybody is a social media follower or will "get" the inside joke.
Sheldon
The warning was posted at the front of the manual. The warning had the following header:
"This is so important it even gets put in before the Table of Contents. Please read it carefully."
If that isn't telling the user to take it seriously I don't know what would be. If it is a joke, it's disgraceful. If it is for real, it means the product is junk. Either way, this is my first and last Rapido purchase.
John-NYBWWhatever the actual case is, it is enough of a reason for me to never buy another Rapido product.
I haven't had reason, yet, to open mine up but I will someday to put some peeps inside.
This site has a good photo reference to what's inside the Rapido models.
https://www.alfray.com/trains/ho_rapido_rdc.html
There's a photo showing the motors and drive shafts (also refered to as dogbones by some modelers).
I have had some Broadway and Proto drive shafts wear down and spin in the flywheels. These are ones where the hex ends got rounded off just enough to allow one to spin inside the hex socket in the flywheel.
I took the warning from Rapido seriously. I was following along when these were being developed and because the motor was being concealed below the floor some compromises had to be made. I simply run mine as a pair and have never had any issues with them.
Regards, Ed
John-NYBW gmpullman John-NYBW The problem is I have been unable to locate a Rapido RDC-1 to pair with the RDC-3. Before receiving this RDC-3, I had ordered a P1K RDC-1, not realizing this would be an issue. That hasn't arrived yet. The Proto 1000 RDC has a top speed of about 45 SMPH. You're going to have to really reduce the top speed of the Rapido model if you plan to MU the two. I really don't recall what the default CV3 - 4 settings were on the RDCs. It has been a while since I've had them on the Lokprogrammer. Generally I give all my new locos a thorough trial on the test track and make necessary adjustments to the functions as needed. I agree the WOWsound concept is not for everyone and, IMHO they should let the user decide to add momentum to their liking. TCS offers a "mainline mode" or "switching mode" which also effectively turns off momentum but I ignore this and customize the decoder to my liking. I prefer to keep some degree of deceleration momentum depending on the actual gearing and purpose of the engine. Regards, Ed A while back, I picked up a dirt cheap P1K RDC-3 on ebay. Only problem is it is lettered for the Boston and Maine and I can't plausibly run that on my layout. I'm going to check to see if the P1K and Rapido RDC-3 shells are interchangeable in which case I would have two P1K RDCs lettered for the New York Central. Since the Rapido came with factory DCC/Sound, I could use that decoder in one of the P1Ks and would then only need to get one non-sound decoder for the other P1K. All this of course depends on the shells being interchangeable.
gmpullman John-NYBW The problem is I have been unable to locate a Rapido RDC-1 to pair with the RDC-3. Before receiving this RDC-3, I had ordered a P1K RDC-1, not realizing this would be an issue. That hasn't arrived yet. The Proto 1000 RDC has a top speed of about 45 SMPH. You're going to have to really reduce the top speed of the Rapido model if you plan to MU the two. I really don't recall what the default CV3 - 4 settings were on the RDCs. It has been a while since I've had them on the Lokprogrammer. Generally I give all my new locos a thorough trial on the test track and make necessary adjustments to the functions as needed. I agree the WOWsound concept is not for everyone and, IMHO they should let the user decide to add momentum to their liking. TCS offers a "mainline mode" or "switching mode" which also effectively turns off momentum but I ignore this and customize the decoder to my liking. I prefer to keep some degree of deceleration momentum depending on the actual gearing and purpose of the engine. Regards, Ed
John-NYBW The problem is I have been unable to locate a Rapido RDC-1 to pair with the RDC-3. Before receiving this RDC-3, I had ordered a P1K RDC-1, not realizing this would be an issue. That hasn't arrived yet.
The Proto 1000 RDC has a top speed of about 45 SMPH. You're going to have to really reduce the top speed of the Rapido model if you plan to MU the two.
I really don't recall what the default CV3 - 4 settings were on the RDCs. It has been a while since I've had them on the Lokprogrammer. Generally I give all my new locos a thorough trial on the test track and make necessary adjustments to the functions as needed.
I agree the WOWsound concept is not for everyone and, IMHO they should let the user decide to add momentum to their liking. TCS offers a "mainline mode" or "switching mode" which also effectively turns off momentum but I ignore this and customize the decoder to my liking.
I prefer to keep some degree of deceleration momentum depending on the actual gearing and purpose of the engine.
A while back, I picked up a dirt cheap P1K RDC-3 on ebay. Only problem is it is lettered for the Boston and Maine and I can't plausibly run that on my layout. I'm going to check to see if the P1K and Rapido RDC-3 shells are interchangeable in which case I would have two P1K RDCs lettered for the New York Central. Since the Rapido came with factory DCC/Sound, I could use that decoder in one of the P1Ks and would then only need to get one non-sound decoder for the other P1K. All this of course depends on the shells being interchangeable.
There is no logical reason why the shells would be interchangeable?
For one, just based on the dramatic difference in detail level between the two models, not to mention that one was made 18 years ago? By a different company?
John-NYBWIf an unpowered car is towed behind it, the warranty is voided. If I'm reading the warranty correctly, I can't even couple it with a powered RDC from another manufacturer. It can only be coupled with other Rapido RDCs. It further states that the RDC is equipped with a detector that can determine if another car is towed by the RDC.
In reality I think it can't be that fragile... What if the RDC derails or gets stuck on something, such that its at a dead stop with wheels spinning? Or what if you have two coupled Rapido RDCs and one suddenly loses power and becomes a dead weight? They can't possibly have produced a model that would break a drivetrain over stuff like this.
More plausible is that the drivetrain is strong enough to force wheelslip at factory weight without breaking. If that's the case, coupling an unpowered trailer would be no problem. Adding a pound of weight so that it can pull a whole train is a different story.
When I read that statement in the manual, I wondered whether the very steep grades on my layout would damage the RDC. I emailed Rapido and they said steep grades are fine and could not damage the drivetrain. So if it can apply enough torque to go up a nearly wheelslip-inducing hill, could it not also apply enough torque to tow something?
I would be happy to test mine running for an hour hauling a trailer for you, but it can't do the full loop of my layout yet until I get around to fixing a clearance issue with a tight corner into a bridge... it's longer than any car I originally designed the layout for.
Thanks Ed, glad I never invested in any of those.
ATLANTIC CENTRALEd, I have a question about the slow speed of the Proto1000 RDC. Was that DCC equiped? Any idea why so slow?
Both before and after a decoder was installed Sheldon. Slow as mud. I'm not sure if it is still offered but NWSL had engineered replacement gearing that was supposed to get the speed up to par, maybe not as high as 80 but better than the Life-Like gearing.
https://nwsl.com/products/double-compound-gears-26-teeth-19-teeth-lifelike-rdc-increases-speed-from-45-mph-to-72-mph
I looked them up and I believe they are still available. I had four of the old Protos and gave them away after the Rapido models came along rather than invest an additional $50/ea. to speed up the SpeedLiners.
I agree, too, about the paint. It was more like a silver sparkle finish. For a stainless representation nothing beats the Walthers plated finish.
Cheers, Ed
Ed, I have a question about the slow speed of the Proto1000 RDC. Was that DCC equiped? Any idea why so slow?
Or was that after adding a decoder to a DC model? I don't even remember how they were offered?
I knew a few guys who had them, but I never ran them.
I just remember inconsistant paint finishes that turned a lot of guys off.
John-NYBWThe problem is I have been unable to locate a Rapido RDC-1 to pair with the RDC-3. Before receiving this RDC-3, I had ordered a P1K RDC-1, not realizing this would be an issue. That hasn't arrived yet.
That is interesting.
I considered replacing my Athearn RDC's when the Proto1000 models came out, and again when the Rapido models came out.
In the end, since many of my passenger cars are selectively compressed, I decided to stay with the Athearn model.
And like you with that item on Ebay, I simply could not bring myself to spend $250 each to replace an operational fleet of 6 RDC's.
So someone will ask why do I need 6? Actually I need 7 or 8. My operational scheme for the new layout calls for 4 commuter trains. Two made up of Bachmann doodlebugs with trailers for the west side runs and two made up of pairs of RDC's for the east side runs.
The other two are B&O, now about to be three or four, to simulate the Daylight Speedliner.
I have about $45 invested in each of 6 RDC's now, with Ernst gear drives and can motors, and I have some other drive line options to test. But even if I invest in better drivelines for the existing 6, I think I'm staying with the Athearn models.
The Rapido model is very nice, but I am getting more and more gun shy about ever more expensive models for which one might never find a service part down the road.
I already have a service part inventory for most of my Proto2000, Bachmann, and Athearn locos.
Ed,
The problem is I have been unable to locate a Rapido RDC-1 to pair with the RDC-3. Before receiving this RDC-3, I had ordered a P1K RDC-1, not realizing this would be an issue. That hasn't arrived yet.
I've run into another problem. After bringing the RDC-3 up to speed, it takes forever to bring it to a stop. I can think of two possible explanations. If I remember right, CV3 and CV4 control acceleration and deceleration rates. I'm OK with a gradual acceleration but I want my locos to stop quickly when I shut off the throttle. The manual suggests using a 21 pin ESU LokPilot for non-sound decoder installation so I'm guessing that this factory installed Sound/DCC decoder is a LokSound. I haven't had a chance to look up what setting to use for CV4 to get a more rapid decleration. I want to control the decleration with the throttle instead of having the decoder determine how gradually to stop the loco. Do yours have LokSound or LokPilot decoders and if so, what have you set your CV4 to?
The other possibility is something I ran into with a WOW-Sound decoder which has a default that requires you to apply the breaks manually while decelerating the throttle. This might be the dumbest idea anyone has come up with in the history of model railroading but at least it is possible to shut that feature off which I have done with my one and only WOW-Sound decoder. If that feature is incorporated into the factory decoder for the RDC-3, the manual doesn't mention how to turn it off. There is an option which requires the brakes to be applied but that only affects the sound according to the manual and is only in effect if F3 is activated.
EDIT: I had to refresh my memory on CV3 and CV4 settings since it had been awhile since I'd done that. Looks like the lower the number, the less momentum. I think I have set all my CV4s to zero because I can control deceleration with the throttle but if I need my loco to stop right away, I can do that.
Sometimes I think the decoder manufacturers are getting too clever. I prefer the KISS approach.
John-NYBWIf I'm reading the warranty correctly, I can't even couple it with a powered RDC from another manufacturer.
THAT is something I definitely wouldn't do with the Rapido RDC. If the second unit (a Proto 1000?) hesitates or hits a dead spot in the track you're sure to "torque" the tiny drive shafts of the Rapido units. Especially since the motor would already be spinning then the axles grind to a halt. Too risky.
I have a pair of New York Central RDCs from Rapido and they run very well. While the NYC did tow the RDCs to outlying junction points that's something I'm not prone to model. I run the pair together and like the way they operate.
Rapido Beeliner by Edmund, on Flickr
Cheers, ED
I just received a Rapido New York Central RDC-3 from an ebay seller. It was NIB. I opened the manual and right at the front it states Rapido has the same warranty condition Budd had for the 1:1 scale RDC. If an unpowered car is towed behind it, the warranty is voided. If I'm reading the warranty correctly, I can't even couple it with a powered RDC from another manufacturer. It can only be coupled with other Rapido RDCs. It further states that the RDC is equipped with a detector that can determine if another car is towed by the RDC. I find this both interesting and amusing.
Overmod Budd officially disapproved of even lightweight/purpose-built trailers to run with RDCs, and I believe would cancel the warranty if they found anyone doing that. In part this was because of the mechanical torque-converter/lockup drive to only the inside axles. You'd need considerably better cooling of the converter oil to accelerate the car plus trailer to lockup speed, and the Detroit 110s were smoky enough without being lugged. As I recall Keilty discusses this in the doodlebug book... All the varied cars in B&O's Daylight Speedliner were RDCs (but ISTR some Budd cars only had one engine and no driving cab; these might be thought of as 'assisted trailers' in a longer consist. The other railroad that had more than a buffet kind of food operation was the Reading, on the Crusader and Wall Street 'replacements' that ran all the way into 1983 (but I don't know if they served breakfast that long...I only rode the train before Conrail took over).
Budd officially disapproved of even lightweight/purpose-built trailers to run with RDCs, and I believe would cancel the warranty if they found anyone doing that. In part this was because of the mechanical torque-converter/lockup drive to only the inside axles. You'd need considerably better cooling of the converter oil to accelerate the car plus trailer to lockup speed, and the Detroit 110s were smoky enough without being lugged. As I recall Keilty discusses this in the doodlebug book...
All the varied cars in B&O's Daylight Speedliner were RDCs (but ISTR some Budd cars only had one engine and no driving cab; these might be thought of as 'assisted trailers' in a longer consist. The other railroad that had more than a buffet kind of food operation was the Reading, on the Crusader and Wall Street 'replacements' that ran all the way into 1983 (but I don't know if they served breakfast that long...I only rode the train before Conrail took over).
The RDC-9 was a single motor, no controls trailer that Budd offered later on in RDC production. To my knowledge the Boston and Maine was the only original purchaser of them. Later RDC's had a boost in HP from 275 to 300, and all RDC-9's had the more powerful engine.
The B&O Speedliner cars were all standard two engine RDC's, RDC-2's converted to add the dining section, and RDC-1's. The typical consist was the RDC-2, baggage/diner/coach and two RDC-1 coaches. But addtional RDC-1's were added from time to time.
Commonwealth Railways in Australia bought 3 off the shelf RDC1's which did tow lightweight boxcars as they were used initially with Narrow Gauge connections on the Central Australian Railway to Marree in South Australia and baggage needed to go somewhere. I have ridden a few of these where there were a number of RDC's with an equal number of the box cars. Gradients were not much of an issue on Commonwealth lines but it was understood that Budd would not cover any warranty.
5 "shorty" RDC's were built for New South Wales by Commonwealth Engineering the Budd licensee here, one of which was a trailer but it was never included in a consist less than 4 cars. It was recognisable because the rooftop radiator was visibility shorter. The "shorty nature" was due to the lesser loading gauge and tighter clearances in New South Wales.
Cheers from Australia
Trevor
gmpullmanSomewhere I came across information that the torque converter was a modification of the Allison CD-850 (weighing 1678 lbs.) also used in M46 Patton tanks.
That is correct as I understand it. Allison also made marine gears using this fluid coupling configuration that allowe larger screws to be started from smaller engines. This proved to be a temporary solution.
Allison heavy duty transmissions were installed in some Cadillacs and Buicks, but I do not have the depth of knowledge to know how similar they were to the one used in an RDC.
The reason the RDC had two engines was because of the weakness of this drive system. Detroit Diesel made engines small enough and powerful enough to run an RDC alone, but a single drive was too weak.
One of the neatest things I ever saw was a Korean War era minesweeper with four 6-71s for power driving one of these drive couplings through an arrangement of three differentials. It looked like a $100.00 solution for a 25 cent problem.
When the local Seminole Gulf Railway demotored their three RDCs, I took one of the 6-110s apart just for fun. It was very similar to the 71 series engines. I could not get the cylinder liners out with the tools I tried to improvise.
I wanted to take apart one of the drive couplings, but there was not enough time for that.
It all went to Garden Street as scrap.
-Kevin
Living the dream.
Minneapolis & St.Louis bought an RDC to replace a regular passenger train, pulling a new Budd streamlined coach. EMD warned M-St.L several times that an RDC could only pull itself, but the railroad continued to pull the coach until in short order the RDC motor burned itself out. Then they continued running the train only using an ancient 'doodlebug' pulling the streamlined / air-conditioned coach.
Yes, the RDC was a truely cutting edge, up to date machine, with all the latest technology.
How many years later before automobiles had lock up torque converters or disc brakes?
My first train ride not on a tourist line, was on a B&O RDC at age 6.
So they will always hold a special memory for me.
ndbprrThis may be a stretch but many years ago I was told by a Budd employee that the original transmissions were Buick dynaflow supplied by GM.
Somewhere I came across information that the torque converter was a modification of the Allison CD-850 (weighing 1678 lbs.) also used in M46 Patton tanks.
If you scroll to Post War Era 1949 here you can see a photo of it:
https://www.allisontransmission.com/company/history-heritage
Maybe some of those big Buicks had the same one. I've heard people say that old Roadmaster drives like a tank!
Detroit 6-110 Budd by Edmund, on Flickr
The power units were mounted on rails that allowed fairly simple removal for service or replacement.
The original air brake system was a NYAB 26-B-1 using Budd disc brakes with a brake cylinder on each wheel (disc) with Rolokron anti-slip devices.
The more I learn about RDCs the more I'm impressed with their design.
The self contained heating system run off the engine cooling system can be switched over to steam heat when made part of a regular passenger train. Likewise the air conditioning can be operated while in a regular train as long as at least one engine is running at idle to keep the batteries charged.
They had electricly heated windshield glass. The New Haven had some RDCs (Roger Williams) equipped with 3rd rail shoes and electric traction motors on the outer two axles for GCT use.
Excellent information in this Budd brochure:
https://streamlinermemories.info/Budd/Budd49RDC1.pdf
Kalmbach just sent me an email about this DVD about RDCs.
Budd Rail Diesel Car DVD - Kalmbach Hobby Store
It's on pre-order right now. It might answer some of the questions I posed.
This may be a stretch but many years ago I was told by a Budd employee that the original transmissions were Buick dynaflow supplied by GM. That could explain why towing a car was not possible. There was a definite point at which the transmission shifted into high and rpms dropped off from my reccolection of riding one to the New Jersey shore
John-NYBWI also read that they were used on a Philadelphia-Pittsburgh train with dining car service. None of the versions of the RDC I read about were diners so this would indicate a standard dining car was part of the consist.
Many railroads modified RDC's equipped with baggage compartments to replace the baggage section with a food service counter and a couple tables. I have had breakfast on the RDG "Wall Street" train between Phillie and New York. No dining car, just 20 ft of the RDC devoted to food prep.
John-NYBW NVSRR By the time RDcs appeared, mail service was mostly done. so some of the RPOs could have been converted to buffet/diners Shane The RDCs first appeared in 1949 and were manufactured until 1962. The USPS cancelled their rail mail contracts in September of 1967. What doomed the RDC was a law passed in 1958 that allowed railroads to abandon passenger service on lightly traveled branchlines. Budd ceased manufacture a few years later. Existing RDCs continued to see service as commuter trains with some still in use in the mid 1980s.
NVSRR By the time RDcs appeared, mail service was mostly done. so some of the RPOs could have been converted to buffet/diners Shane
By the time RDcs appeared, mail service was mostly done. so some of the RPOs could have been converted to buffet/diners
Shane
The RDCs first appeared in 1949 and were manufactured until 1962. The USPS cancelled their rail mail contracts in September of 1967. What doomed the RDC was a law passed in 1958 that allowed railroads to abandon passenger service on lightly traveled branchlines. Budd ceased manufacture a few years later. Existing RDCs continued to see service as commuter trains with some still in use in the mid 1980s.
Regarding the B&O Daylight Speedliner.
It originally ran from Philly to Pittsburgh - via Baltimore and DC - then to Pittsburgh.
After April of 1958 it ran from Baltimore to DC, then to Pittsburgh - no Philly connection.
The B&O converted two RDC-2's (baggage/coach) to baggage/cafe/coaches for the train. Both cars still survive today.
The B&O had extensive shops and typically built all manner of equipment from near scratch. Making an RDC diner was no big deal.
The roughly 330 mile route of the Daylight Speedliner was well within the range of the RDC's.
The train was normally 3 cars, the baggage/diner/coach and two coaches. Since the B&O had other RDC's, a third coach could be added when needed. I have seen pictures of the Daylight Speedliner with 4 cars.
Service was discontinued in January of 1963.
I plan to stretch history a bit (I model Sept. 1954, the RDC Speedliner started in '56) and model the Daylight Speedliner on my new layout, as the layouts fictional location is north of DC, west of Baltimore, and interchanges with the B&O at my fictional "Potomac City".
The ATLANTIC CENTRAL also uses RDC's for commuter service around Potomac City.