Hi Imran,
If it works, why change it? Simplification might create changes in the function.
Here is a simplified version, as requested:
https://www.amazon.com/clouddrive/share/D2NN8lIIyGMGQrLonU16RqzPPs1viLwW7CoitGfBHpo
While the file you provided has no problems with scene refresh (Press the “a” key), it works not flawless either: move the timeline backward, and the motor rotates anyway (It should run as well as back then). The simplified version reacts even on the refreshing (a key)
Since the request was defined as slowly increase the speed, this might work:
https://www.amazon.com/clouddrive/share/4HFQoWIekFNtchBOZGn7uuKlGmh7vl3lqUJQehH6DxB
It is stable while the time line is changing, both ways.
Alternative
MoGraph Based. (Deform>Object)
https://www.amazon.com/clouddrive/share/x1f39LhiyAWj2l9Qp0t7tgQHO18HgHlHeVPBge4rTXB
Both do not work, with slow down.
All the best