EMB ERJ 170/175 ER/LR
Flight Crew Air Transport Pilot (ATP)
Flight Crew Type 8000
Aircraft Equipment Problem Critical
Flight Crew Overcame Equipment Problem
Aircraft
During approach turned off the autopilot; the switch worked properly and heard the aural 'autopilot ' warning. Attempted to move the yoke but it was locked up on all axes; the FO tried his side and was locked as well. We had no indications on EICAS and and no other abnormal indications.  I tried to introduce some power and back pressure to see if I could keep the plane in the air and didn't like the response.  With low fuel and no flight controls; trying an autopilot go-around seemed like a very poor idea so I had the FO come up on the controls and together we broke free whatever was stuck. Later learned I had to apply significant lbs of force to break it free. I recovered the aircraft and landed without incident.
Reporter stated that Maintenance advised them the problem was caused by an autopilot servo malfunction.
ERJ-175 Captain reported they found the flight controls were locked in all axes after disconnecting the autopilot at on short final.  The Captain and First Officer applied enough force to break the controls free and landed without further incident.