I just bought 3 new Intermountain SD40-2’s ( Santa Fe, CSX, Soo ). All 3 have what sounds like a growl in the gears. Using my NCE power cab ( 28 speed step ), I don’t hear it, under say, speed step 10. But at 15, It’s noticeable and at 28 it’s really noticeable. It’s seems more pronounced on curves ( 26" ).
Is this normal for Intermountain? BTW, I’m running them with the sound off. If I turn the sound on, of course it’s not as bad. Only bothers me because my cheap Bachmann F unit with value sound, is quiet at all speeds.
On Edit:
Want to mention, all 3 were bought from different dealers, 2 of which I know have a good turn over on thier stock. So I dont think its just a case of dried/no gear lube. I dont want to tear into them untill I find more info on this.
You might consider contacting Intermountain directly. I have several Intermountain F series locomotives which all run quietly. However, initially I did have a squeak in one motor and Intermountain replaced the motor even though I had bought the locomotive on eBay. They have also been really good responding to several other requests that I have made.
I have a non sound Santa Fe unit. I have been using it for some of my testing. I really had not thought much about the noise or lack of to date.
Because of this question, I decided to run a quick series of tests to listen to the noise. My tests are done with DC. My DC bench supply does not do pulse, so the decoders handle it just fine. Pulsing a decoder causes problems.
my guess is your speed step 28 is roughly 14 volts give or take. My unit, that is new out of the box with at most 2 hours of test time, had a audible gear noise at this voltage. On a comparative assssment, it is quieter than most of the engines that I have tested at this voltage, but it is still noticeable.
The noise persisted down to 8 volts, which is approximately SS 15 if the variation is linear. The noise is much quieter, but still there.
The question is relative to what. My impression is that the engines that I have tested that are quieter are also poor mechanical performers. I do not normally test for noise, because my hearing isn’t what it use to be and I do not have the proper equipment or facility to adequately measure the differences. The statements about the above tests are at best qualitative.
For other reasons, I have been anticipating additional tests on this unit. My usual practice is to change the lubrication on my keepers. The testing so far has been as received. These results reaffirm the need for the lubrication activity. A number of other questions are to be answered about this unit, so it will be a while before everything is sorted out.