Bristol, Teno. This invention provides an improve ment on a former patented invention of the same in ventor, being a circuit-closing device for use in connec tion with a system employing a rotary commutator. The invention consists of a peculiar construction and arrangement of devices whereby a depressi ble bar acted upon by the car wheel is made to adjust the commuta tor to position for making the circuits, hold it in tpis position for a limited time, and then allow it to be reo stored to its normal position.