Continuous rotation torque wrench

A torque wrench, comprising:

• an input end configured to receive a torsional input;
• a sealed housing containing pressurized lubricant;
• a gear train disposed inside the housing and operatively driven by the torsional input;
• an engagement unit configured to selectively create a mechanical coupling between the input end and a lever or motor;
• and
• an output end operatively driven by the gear train to produce a torsional output,
• wherein the gear train is sealed inside the housing from a surrounding environment at a positive pressure relative to the surrounding environment when the lubricant is inserted, wherein a unidirectional valve is connected to the housing and configured to pass the pressurized lubrication unidirectionally into the housing, and wherein the housing is sufficiently sealed and the positive pressure is sufficiently high to prevent water from passing through the unidirectional valve when the torque wrench is used underwater.