# SD70MAC loading issue.



## Engineercub (Oct 18, 2008)

On my division, there have been many people saying that the SD70MAC/SD70ACe is junk and/or has loading issues. This is not the case at all. I have been noticing this "issue" on the SD70MACs for a while and figured out what the problem is. First of all, to those saying it is not loading throughout their whole trip, it is most likely because someone has gone into the diagnostics display and changed the loading value because on their division they have mostly flat territory and it allows them to stay in the same throttle position the majority of their trip. To correct this problem you have to go into "Speed Control" and change the loading value to 1:1 but I think you can only do this while in throttle#1 or higher. I don't have step by step instructions on this but next time I run a MAC I will be sure to write it down. The second issue is they are "slow to load" when on a grade. This is normal and is a feature of the newer 70MACs and all 70ACe's. Basically, as you know, when you try to start your train on a grade you have to have it loaded pretty high to get traction started. If the previous Engineer did not stop the train using stretch braking then it could roll back on you while you are pulling thousands of Amps on the head end and causing you to snap a knuckle. To avoid this, the newer 70MAC/70ACes have a feature that loads you up to the amperage of your throttle position but it won't allow you to move forward for several seconds. It is basically holding you stationary while your train brakes are releasing and reducing the chance of you getting a knuckle due to someone making a bad stop before you got on. There is probably a way to toggle this feature off for switching purposes which is why many Engineers are complaining but I have not run the 70ACe enough to really familiarize myself with the new settings in the diagnostics. If anyone is having these problems with the new EMDs let me know, I can help.

-Will


----------



## NTCGRR (Jan 2, 2008)

Will 
and whos world are you living in???? 
Get your mind back on your GRR.


----------



## Greg Elmassian (Jan 3, 2008)

I know Marty HAS to be joking. 

I find your post very interesting, although I do not understand all the terms. Please post the follow on info when you do run one again. 

Regards, Greg


----------



## GG (Jan 1, 2009)

Will, 

Can I put one of these puppies on my layout?

I have lots of grades and I never stop in the right spot...


gg


----------



## markoles (Jan 2, 2008)

Will,

It sounds like the EMD Electrical Engineers are trying to outsmart the railroad Engineers. Or, is it like that fancy car I test drove the other day. It is a 6 speed manual, that has a slight hill assist. Essentially, you have 3 pedals to work but only 2 feet, so when you are stopped at a light on a slight hill, releasing the brake to hit the gas and release the clutch, there is something built in that prevents the vehicle from rolling backward. BUT a true driver of a manual transmission wouldn't need the hill assist, now would he (just me, who hasn't driven a manual in over 5 years)? 

One question. Lets say you are stopped on a downhill with the train stretched. In that case, wouldn't you want the brakes to hold while you load to keep the knuckles stretched? And I thought that with the newer braking systems, the engineer could release the brakes from the rear of the train first, thereby eliminating the control required you've described? In any event, are you aware of the SD70's success? It seems like they weren't that popular with road crews and railroads have been going with the SD90MAC instead. Just some armchair observations. 

Last observation, I like your word choice 'feature'. We used to use that to describe Microsoft's WIndows Operating System glitches.....


----------



## aceinspp (Jan 2, 2008)

Mark you would not stretch the train on a descending grade you would do the opposite . Other wise the slack now runs into ya when the brakes are released. Later RJD


----------

