toroidal coil (electrical component). An electrical inductor wound around a ring-shaped core made of a highly permeable material. The ring-shaped core concentrates the magnetic flux and allows a minimum amount of flux to be lost in an external field.
torque. A force that produces or tries to produce rotation. torque limited (turboprop or turboshaft engine limitation). A limit placed on a turboprop or turboshaft engine that restricts the amount of power the engine is allowed to deliver to the propeller or to the
rotor-drive system. This limit is imposed because of the strength of the drive-train mechanism or the strength of the aircraft structure. torque links (aircraft shock absorber component). A hinged link between the cylinder and piston of an
aircraft shock absorber. Torque links prevent the piston from turning inside the cylinder, but they allow it to move up and down to absorb the landing and taxi shocks. Torque links are also called scissors and nutcrackers.
torquemeter. An instrument used with some of the larger reciprocating engines and turboprop engines to measure the amount of torque the engine is producing.
torque tube (aircraft control system component). A tube in an aircraft control system that transmits a torsional force from the operating control to the control surface. Torque tubes are often used to actuate ailerons and flaps.
torque wrench (precision measuring tool). A precision hand tool used to measure the amount of torque being applied to a threaded fastener by the wrench. Torque is normally measured by measuring the amount a beam in the wrench bends when the torque is being applied. See deflecting-beam torque wrench.

torr (unit of pressure). A unit used to measure a low pressure or vacuum. One torr is equal to one millimeter of mercury, or 1/760 of the standard atmospheric pressure.
torsional force. A twisting force. A torsional force is made up of a tensile force and a compressive force acting at right angles to each other and at 45° to the axis of the object. Torsional forces are the main forces acting on propeller shafts and helicopter rotor shafts.
torsion rod. A device in a spring tab to which the control horn is attached. For normal operation, the torsion rod acts as a fixed attachment point, but when the control surface loads are high, the torsion rod twists and allows the control horn to deflect the spring tab.
total pressure (Pt). The pressure a moving mass of fluid would have if it were stopped. Total pressure is the sum of static pressure and the pressure due to ram effect.
total temperature (Tt). The temperature of a fluid that is stopped from its motion. Total temperature is the sum of the static temperature of the fluid and the temperature caused by ram effect as the fluid is stopped.
touch and go (aircraft operation). A type of flight practice in which the pilot makes a series of landings and takeoffs. The landing is made, but the aircraft is not allowed to come to a complete stop before power is applied and the takeoff is made.