In most cases, the built-in speed curves work just fine. With features such as V-Start, V-Mid, and V-Max, it's generally possible to match speeds of dissimilar locos. However, if you can't attain the speed curve you want by modifying the built-in curve(s), you can always use the User-Loadable Speed Table to install the exact curve you want.

There are other purposes for the User-Loadable Speed Table, such as setting up a special curve for turntable or transfer table operation, and other layout animation needs. Again, these things can usually be handled with other features such as V-Start, V-Mid, and V-Max, but the User-Loadable Speed Table is there if you need it.

The User-Loadable table provides 28 CVs for the table (67-94), plus three others (65, 66, and 95) for fine-tuning. CV67 is for speed step 1 in the 28-speed-step mode. 68 is for speed step #2, and so on all the way up to 95 for speed step #28. CVs 66 and 95 are Forward and Reverse Trims. CV65 is Kick Start, to help the loco get started on speed step 1.

With some decoders, the User-Loadable Speed Table can only be used in the 14- or 28-speed-step mode. However, some decoders can use it in the 128-speed-step mode by stretching the 28 CVs up throughout the entire 128-speed-step range and interpolating what the in-between speed steps would be.

Equipment Requirements to Have a User-Loadable Speed Table

The User-Loadable Speed Table is a decoder feature. Once programmed it will operate from that speed table on any system.

Digitrax decoders provide the User-Loadable Speed Table in the 28- and 128-speed-step modes. They are supposed to support Kick Start and the Trims, but they are flawed on at least some of their current decoders.

Train Control Systems decoders provide the User-Loadable Speed Table in the 28- and 128-speed-step modes. They also support Kick Start in the User-Loadable Speed Table as well as the built-in speed curve, but do not support Forward and Reverse Trims.

Throttle Up! (SoundTraxx) sound decoders provide the User-Loadable Speed table in the 28- and 128-speed-step modes. They also support Kick Start and the Trims with the User-Loadable Speed Table as well as with their optional built-in speed tables.

Since the User-Loadable Table resides in CVs 67 through 94, and have supporting CVs 65, 66, and 95, you'll need a system or other method for programming those CVs.

All of Digitrax's current systems can program any value into any of these CVs.

One option that many people who use the User-Loadable Speed Table like is programming decoders with a computer. Software for programming decoders usually provides a graph that allows you to use the mouse to draw the calculated curve in, then program the whole thing with the press of a button. Three products for doing that are: PR2 with provided software and WinLok with the PC connected to LocoNet with an MS100 interface.

WinLok can only program decoders using the system programming track if you have a Chief, and are not program-compatible with Empire Builder programming.

The User-Loadable Speed Table is not intrusive. You do not need to bother with it unless you want to use it.