No one seems to be able to give me the technical reason why this is possible. A speed step is a speed step. Set by the R2LC and driver board in older TMCC engines. How does Legacy improve this??? It's been reported so it must be true but I don't see how.


Anyone out there with the knowledge they can share?

This message has been edited. Last edited by: superwarp1,

Gary,

The Legacy system controls the speed step profile to the loco. By using absolute speed steps and controlling the step profile we attain a smooth rate of control and get better performance.

If the loco modifies the acceleration ramp (IE: aftermarket cruise) then the Legacy control system benefit is lost. However, the aftermarket products have added more speed steps to attack the problem of performance before Legacy was delivered.

In the case of the Pullmor, the Legacy controlled speed step profile is a boon to performance; especially when a little momentum is applied. The R2LC only gives you 3 basic momentums - fairly granular; the Legacy system gives you 8 different momentums in the step profile - and thus you can select the best performance using the Cab-2.

Essentially: absolute speeds steps combined with a wider range of momentum selection give you much smoother control.

Legacy improves TMCC operation because the commands are absolute. That keeps lash-ups of like locomotives in complete sync at all times. No variation. A big improvement!

But my favorite improvement is a combination of absolute speed commands and momentum. Legacy momentum is different. It sends out sequential speed commands at an even rate that is adjusted by the momentum setting. That means that Legacy digital control is sending out EVEN increments in acceleration or deceleration at a STEADY and specific rate. That translates to SMOOTH operation. Try momentum 4 or higher with a TMCC locomotive. It is astounding the difference this makes!

These improvements to TMCC are possible because every TMCC locomotive ever made has absolute speed steps built in (32 of them compared with Legacy's 200), allowing Legacy absolute control of TMCC. Lionel kept those absolute steps in TMCC over the years, even though they were not in use with CAB 1, which is strictly relative control ( one up, one down, etc), not absolute. There were some hard fought battles inside the company about keeping those or dropping them, and this is one time when future operation capabilities won out! TMCC is now reaping the rewards of that technology.

Hope this helps.
ny

Interesting Jon. How come some with EOB report better performance with Legacy.

Thanks for the quick response.

Gary,

Well I am not an EOB expert, but I can tell you of my experience. I have a Lionel Mikado that I upgraded to EOB. The loco operates a lot better with EOB, although it still only has one puff and 2 chuffs! I digress.

With Legacy, the Mikado works only in CAB-1 mode. If I put the loco into 32 speed steps, the Cab-2 won't control the loco in TMCC mode. If in 128 speed step mode, CAB-1 mode is my only choice.

Since the CAB-1 mode on the Legacy system works exactly as the CAB-1 remote, IMHO Legacy does not improve this loco's operation. I have heard that there is a newer chip for EOB to add absolute 32 speed step commands, but honestly I have little interest in opening my loco and installing the chip.

I believe that if I added the new chip, the speed graph would not match the loco operation, and the Cab-2 momentum would not be fully functional as intended, rather additive to the built in momentum EOB seems to have. Perhaps between the CAB-2 momentum feature and the built in EOB momentum, I may see a bit of an improvement - in 32 speed step mode only.

I think EOB is a fine system, fills a needed niche in the hobby, and I like the elegance of the design; however the operation of EOB is slightly "out of sync" with genuine TMCC architecture locos. The momentum control fully under Cab-2 control gives a user the best experience, IMHO.

jon
Disclaimer: This post is based on personal feelings, and not a statement or an opinion from Lionel LLC.

I'm glad the absolute steps were retained!!! I have built a home-brew automated system controlling an arbitrary number of trains without collisions, and the absolute speed commands are essential. So they are useful for a few tinkerers as well.

quote:

Originally posted by ny:
Legacy improves TMCC operation because the commands are absolute. That keeps lash-ups of like locomotives in complete sync at all times. No variation. A big improvement!

Neil, I was not aware that speed steps were identical for different locos i.e. an absolute speed of 16 on a SD-70 is equivalent to an absolute speed of 16 on a Hudson. Additionally, I believe that you loose effects such as 'Brake Squeal' when the engine is controlled with absolute speed rather then relative speed.

Earl

Earl, Neil said "like locomotives." I believe that excludes mixing an SD-70 with a Hudson. Two similar-vintage SD-70's or 2 Hudsons should be OK.

Dale, you're right. I missed the 'like locomotives' when I read Neil's post. Do you have a cure for old age?

Earl

quote:

But my favorite improvement is a combination of absolute speed commands and momentum. Legacy momentum is different. It sends out sequential speed commands at an even rate that is adjusted by the momentum setting. That means that Legacy digital control is sending out EVEN increments in acceleration or deceleration at a STEADY and specific rate. That translates to SMOOTH operation. Try momentum 4 or higher with a TMCC locomotive. It is astounding the difference this makes!

I would agree with ny's comment. When running the Lionel Mogul in TMCC mode and using the momentum setting of about 6 and the train brake, I have pushed back on the train at start up and then moved forward using the roll speed step to start and then selecting a speed range, The start and acceleration is very realistic and you can see the train movement take up the coupler slack. This is improved operation over the Cab-1 TMCC.

Sorry, Earl, but the only cure for old age that I know of involves a lot of dirt! We just aren't going to get out of this alive!!

My casket will have a train running upside down on the underside of the lid....

Over the years I have done a lot of conversions to postwar engines. Primarily, I have used first gen LCRU's, with a smattering of aftermarket boards. The performance improvements that Legacy gives to these converted engines is astounding, indeed.
One caveat I have found is that the levels of control Legacy gives you can magnify mechanical problems that these engines might have. Starting a train with Cab-1 was never an issue, as you don't have a starting benchmark, per se.

Unless you watch the LED on the base you really didn't know what point the consist started rolling. For example, there was a particular engine (675) I have that cogged at step 14, but didn't start to roll smooth (with a big jump) until speed step 18. Totally unacceptable. Seems the armature bearings were worn out, and the armature was wobbling all around the field.

She cog-creeps at speed step 8, free rolls at 10 and the acceleration ramp is 10x smoother. With this encouraging result, I have revisited several of my old converted PW engines to boost overall performance. Not all of them responded as well, but they all have seen some improvement.

When MartyE visited a few weeks ago I wanted him to run my TMCC F3 Texas Special, which up till then I was running in Cab-1 mode only. Marty first adjusted the stall and worked with the M momentum range to see which setting was best. And holy Texas Cow....my F3 runs so good I think it is a Legacy engine. The Legacy RR speeds work great and the sounds are awsome when break is put on. I am a happy camper!

Steve

Texas on the West Coast........