As you must know, the decoder metes out voltage rectified to DC based on your throttle inputs. I can't speak from personal testing or other experience, but I am going by tests our hosts performed on HO locomotives proffered by MTH years ago (it may have improved since the 2010 era?), and they remarked every single time that their MTH sample needed a bear's breakfast worth of voltage to get underway. That suggests to me that the maximum a DCS decoder is going to throughput to the can motor is something near 85-90% of what a DCC system would offer it. So, your very nice Allegheny is speed limited by voltage, and I think you should probably convince yourself that that's the way the MTH H-8 runs. They were not designed for passenger speed, but intended to match the Class A and 2-8-8-4 variants which were intended for similar 'fast' freight speeds...near 60 mph-ish. You're almost there. An H-8 paired with diesels isn't out of order, what what is its role, as a helper or as the head-end power for the consist? If you have to couple ANYTHING to an H-8, it is going to be as an assist, and that's very unlikely. Instead, you're putting an H-8 into helper service to keep a passenger train on schedule...the H-8's schedule, which is it's speed as a designated head-end locomotive on the consist...if you follow. Run it at max for that drive and decoder, and let the diesels be helpers, or simulate the diesels with their combined 2600 hp needing the Brute to help a heavy consist get up the grade as fast as the Allegheny can get it there.
My two cents, but you gotta be happy in the end. I'd say regearing is going to be horribly more involved than just ditching the DCS electrics and wiring in a TCS or something.
Shades_10318 You think the issue is that there's too much voltage drop between the track power and the motor when running on 14V DCC then? I could try testing it with a voltage meter sometime soon to find out about that.
You think the issue is that there's too much voltage drop between the track power and the motor when running on 14V DCC then? I could try testing it with a voltage meter sometime soon to find out about that.
Yes, that's exactly what I think.
Sheldon
If you'd like a bit of context regarding the speed matching, I probably wouldn't run it with the E7, but the rest of the locomotives are speed matched with it, and I would like it to be able to be able to run with the other locomotives in the roster that would actually make a bit more sense. The issue I run into is that it can't run fast enough to keep up with the other locomotives at top speed, and I don't want anyone who would run it to need to remember to keep it at speed step 23 or lower to not have the other locomotives suddenly start running much faster than it. I realize that it's more prototypical to have it running slower, but it's more of a safety thing.
OK, not sure why an Allegheny would be running at 70 with an E7, but it is your railroad. What is "golden" about an E7?
The real Allegheny was designed to pull 5,000 ton at 45-50 mph, likely could have achieved 70 or close to it. They did pull troop trains and mail trains from time to time and likely did see speeds in the 60's.
Here is what you need to know about MTH, their DCS system was designed for O Gauge and then adapted to HO. They even lobbied the NMRA to change the wording of the DC voltage standards to "fit" their products. They run better on a slightly higher standing track voltage than normally recommended for HO DCC.
A true DCC decoder would give that motor a fighting chance to run a little faster.......and no decoder and 14 volts DC would likely make it fly.........
MTH has a long history of thinking they know better than the rst of the industry.
You may be having issues with the Rivarossi product, but trust me, MTH is not immune from product problems, electrical ones in particular.........
I for one will never own one of their locos because they don't run well on DC, and the DC throttles I use may not even work with their tri-mode DCS decoder. And I'm not paying their crazy high prices to then have to remove the decoder and rewire the loco.
My Rivarossi Allegheny runs just fine, and a number of my friends have them as well with no issues........
Thank you for your reply. The locomotives are being speed matched to a BLI E7 (the "golden locomotive"). The Allegheny only has a top speed of 50 smph, if the reviews are to be believed. I don't have access to a scale speedometer, but it is definitely slow relative to the other locomotives.
That's a good point about using a different decoder brand than the MTH one. It hadn't occurred to me. I'm not sure if the issue is actually with the decoder or the motor, though.
I do own a Rivarossi Allegheny as well, unfortunately I have found it to have issues with durability as well as the number of power pickups.
Yes, this is running on DCC. I wonder if anyone has done testing to determine whether it's the motors or the decoders that make the MTH locomotives run better at higher voltages...
OK, here is a thought or two........
What other locos are we speed matching to? Why is a top speed beyond 65 or 70 smph necessary for a loco like this?
I assume from thatyou are using DCC? MTH DCS decoders, that are also DCC (more or less) are known to have some limitations in DCC. Thismight be one of them.
What voltage are you running yor DCC system on? DCS decoders like higher voltages, as noted by all the complaints when people try to run MTH HO locos on DC......
First idea, sell the MTH Allegheny, buy the finer detailed Hornby/Rivarossi Allegheny, and see if you don't have better luck.
OR
Rip out the DCS decoder and install the DCC decoder of your choice in the MTH Allegheny. Then the decoder won't be needing as much voltage and the motor will likely get more..........
One last thought, while I know enough about DCC, I'm a DC modeler. And I double and tripple head steam locos of different brands and wheel arrangements all the time.........with no speed matching.
If locos have similar starting voltages, and the train weight justifies multiple locos, the gearing and speed range only needs to be "close", they will work just fine.
I have been recently working on an MTH HO scale model Allegheny. It mostly works pretty well, but there is just one problem I have with it- it is limited to its prototypical top speed by gearing and motor speed. I would like to be able to get it to run faster for the purpose of being able to speed match it with the rest of the locomotives in the roster. However, when I try to do this, even using the custom speed table settings, I can only actually get it to speed match up to speed step 23. After that, any other locomotives will outpace it.
Any advice on how to speed up this locomotive would be appreciated. I have considered re-gearing, re-motoring, or maybe adding a boost converter to increase the input voltage to the motor control circuitry. None of those seem like great ideas, but replacing the motor would be my first idea if I could find out how to find one that will match the size but outpace it in speed. I have also disassembled the locomotive to look at the gearing, and as I understand it the main gear reduction is in the worm gears, so maybe there would be a way to replace the worm gears with ones with a different ratio. I'm not really sure.