Reverse Lockout. This is an ESC function that prevents accidental engagement of reverse function on an ESC. Reverse is generally not permitted in organized racing, in
order to prevent track mishaps.

Rich. When the needles on the carb are set such that the engine is getting too much fuel it is referred to as running rich. If you accelerate from a stop and the engine dies, you are probably running too rich. And should lean out the engine¡¦s low speed idle adjustment a little (by turning the needle valve or low-end adjustment slightly clockwise).

RPM. Measurement of engine speed; the number of rotations / revolutions per minute.

Runtime. Total length of time a vehicle will run on a single battery pack or tank of fuel.

Servo Reversing. This is just what it sounds like. Radios with this function allow the user to reverse the output of the servo. This is useful when you switch the radio system between vehicles that may use different servo placement or orientation.

Servo. This is the unit that actually does the physical work inside your vehicle. A servo contains a small motor that, when activated by commands from the transmitter, moves the control linkages for steering, throttle and brakes Some vehicles with 3-channel radios have a third servo to activate other functions, such as reverse or shifting of gears.

Servo Savar. A device that protects the servo from excessive force that could damage its gears. It can be integrated into the control horn or the steering bellcrank.

Shock Piston. A small plastic, brass or nylon disk that travels up and down inside an oil-filled shock body. It uses a hole or holes to regulate that rate at which the shock compresses and rebounds.