I have an old autopilot control head that simply outputs a 12v supply to a motor and reverses the polarity to change the direction of the motor to steer in the opposite direction. I am thinking of changing the motor to a linear ram that works the same way by reversing the polarity to push or pull. I suspect that the old autopilot control head cannot cope with the higher amp loads of the linear ram and so I need to find some way to switch the linear rams direction using the reversing polarity via relays (and probably diodes I am guessing). At the moment I just cant get my head around how to achieve this. Could anyone point me in the right direction (no autopilot pun intended)?