This effect simulates the prime mover adjusting to work load variations, such as uneven terrain, while trying to maintain a constant train speed. The rev level may wander up and down the amount selected over the period.
The Rev may wander may be set to 'None' [OFF], '?1 rev' or '?2 revs'.
The amount of time between changes in the rev level based upon the Rev Wandering setting. If Rev Wander Randomization is set, then the Rev Wander may or may not occur within the time frame of (Period ? Randomization). Once the Wander has occurred or the calculated time frame has elapsed (if no wander occurs) a new time frame is calculated and the wander process begins again.
This feature is availble starting with ROM file release version 7605.