Maybe its there to slow a surge of power from the battery when the switch is turned on? These Monorail motors run slower than the same train motors but I don't know if the power is reduced by the gearing or a reduction of the 1.5volts or maybe to protect that circuit board after the switch.
![[Image: 7071.gif]](https://www.allsmileys.com/files/sweetim-texticons/7071.gif)