Reversing Polarity

If the forward and reverse coils in the actuator share a common lead, a SPDT switch or relay will do it.

This is a typical motor reversing switch arrangement, using a DPDT switch.

In linear actuators, it would be wise to use limit switches for both directions. Usually the limit switches are used to operate relays, rather than being wired in line with the motor.

Here is another motor control circuit, which uses relays. The relays are "latched" after the fwd or rev button is pressed. The limit switch contacts would be put in series with the latching contacts, to break the relay control circuit at each limit.