A jackscrew or car jack is a familiar mechanical actuator. Three engineers who signed the jackscrew drawings were convicted. The brakeless retractable main gear used a simple manual jackscrew. The trim is actuated via a jackscrew mechanism. The appliance includes a jackscrew in the middle for patients to turn for expansion purposes. A farmer's jackscrew secured the damage until landfall. The jackscrew figured prominently in the classic novel "Robinson Crusoe".