Hydraulic transmission
Hydraulic transmission may refer to various transmission methods for transferring engine power to drive wheels, using hydraulic fluid:

 Diesel-hydraulic transmission, used in railway locomotives
 Hydrostatic transmission, using hydraulic motors to convert the fluid energy into rotary propulsion
 , using hydraulic rams acting on a swashplate or crank to convert the fluid pressure into rotation
 Hydrokinetic transmission, involving one or more torque converters; commonly used in railway locomotives
 Hydraulic automatic transmissions in automobiles manufactured in the mid-20th century, with trade names such as "Hydromatic"

See also 
 Hydraulic machinery, machinery powered by hydraulic motors/hydraulic transmission
 Hydraulic (disambiguation)