|This drawing shows how to wire two DPDT relays for forward/reverse of a motor.
The hook up is the same in all 4 figures, each figure just shows what happens when each relays coil is turned on. The wiring for the actual coils is not shown. The drawing should be self explanatory but basically in Figrue1 both coils are off which mean no power is going to the motor. In Figure 2 the top coil is on and the bottom is off which sends power to the motor in one direction. In Figure 3 the top coil is off and the bottom is on which sends power through the cross over (just like in the last switch tutorial) and makes the motor spin in the other direction. Figure 4 shows that if both coils are turned on by accident it will not short out, but no power will be sent to the motor. For more info on how to wire the relays for this setup see the Relay Wiring for the Electronically Challenged How To.