61,984 articles
Hydra 70
Hydra 70, also known as the Hydra rocket, is a family of 2.75-inch (70 mm) unguided air-to-ground rockets fired by fixed-wing and rotary-wing US military aircraft.
Hydraulic accumulator
A hydraulic accumulator, or pressure accumulator, is a pressure vessel that stores energy in a hydraulic system by compressing nitrogen gas and releasing fluid on demand.
Hydraulic actuation
Hydraulic actuation converts the energy of pressurized liquid, usually oil, into force and motion via Pascal's law, favored in robots for high power density and impact robustness.
Hydraulic and osmotic artificial muscles
Hydraulic and osmotic artificial muscles are soft actuators that generate motion from liquid rather than a motor, contracting under fluid pressure or deforming as water crosses a membrane.
Hydraulic artificial muscle
A hydraulic artificial muscle is a fluid-driven actuator that contracts like a biological muscle when pressurized with oil or water, offering faster response and higher efficiency than pneumatic muscles.
Hydraulic brake
A hydraulic brake, or hydraulic braking, is a braking system that transmits the operator's pedal force to the wheels through incompressible brake fluid, working on Pascal's law.
Hydraulic cylinder
A hydraulic cylinder is a linear actuator that converts the pressure of hydraulic fluid into mechanical force and motion, powering construction machinery, presses, machine tools, and dump trucks.
Hydraulic engineering
Hydraulic engineering, also known as hydrotechnics or hydroengineering, is the branch of civil engineering concerned with water flow and the design of dams, canals, levees, and drainage systems.
Hydraulic fluid
Hydraulic fluid, also known as hydraulic oil or hydraulic liquid, is the liquid medium that transmits power, lubricates, cools, and seals within hydraulic systems; most are refined mineral oils.
Hydraulic lime
Hydraulic lime is a lime binder that sets and hardens through a chemical reaction with water, allowing mortars to gain strength in damp or underwater conditions, used in historic masonry repair.
Hydraulic machinery
Hydraulic machinery, also called hydraulic drive, uses liquid under pressure to transmit power, from turbines and pumps to fluid power systems with cylinders and valves.
Hydraulic power unit
A hydraulic power unit, also called a hydraulic power pack, is a packaged assembly combining a motor, pump, reservoir, and valves to supply pressurized hydraulic fluid to actuators.
Hydraulic pump
A hydraulic pump is a positive-displacement machine that converts mechanical power into pressurized fluid flow, powering excavators, bulldozers, and forklifts; common types include gear, vane, and piston pumps.
Hydraulic ram
A hydraulic ram, or hydram, is a water pump powered by water hammer alone, needing no fuel or electricity. Joseph Montgolfier built the first self-acting version in 1796.
Hydraulic regenerative circuit
A hydraulic regenerative circuit, also called a rapid traverse circuit, returns rod-side flow to the piston side of a differential cylinder, roughly doubling extension speed at reduced force.
Hydraulic resonance
Hydraulic resonance is the oscillation of a moving mass on the compressible oil column in a hydraulic actuator, often the limit on servo control bandwidth.
Hydraulic stimulation
Hydraulic stimulation is a reservoir engineering method that injects fluid at high pressure to increase rock permeability, used for oil and gas recovery and enhanced geothermal systems.
Hydraulic transformer
A hydraulic transformer is a fluid-power component that converts pressurized hydraulic fluid between different pressure and flow rates at nearly constant power, chiefly for Common Pressure Rail systems.
Hydraulically amplified self-healing electrostatic actuators
Hydraulically amplified self-healing electrostatic (HASEL) actuators are soft artificial muscles driven by voltage, introduced in 2018 at the University of Colorado Boulder and able to self-heal after dielectric breakdown.
Hydraulics
Hydraulics is the engineering science of liquid pressure and flow, covering fluid power systems, where confined liquid transmits force by Pascal's law, and water flow in open channels and pipelines.
Hydrazine
Hydrazine, also called diazane, is a toxic, fuming compound of nitrogen and hydrogen used as a rocket propellant and to make agricultural chemicals and blowing agents.
Hydro Tasmania
Hydro Tasmania is the trading name of the Hydro-Electric Corporation, the Tasmanian government business that generates and retails electricity and is Australia's largest generator of clean, renewable energy.
Hydro-Québec
Hydro-Québec is a government-owned Canadian utility, founded in 1944, that supplies nearly all electricity in Québec and is Canada's largest power utility and electricity distributor.
Hydrocracker
A hydrocracker is a catalytic refinery unit that converts heavy gas oils into jet fuel, diesel, and gasoline by cracking heavy molecules with hydrogen and a catalyst.
Hydrocyclone
A hydrocyclone is a stationary separator with no moving parts that uses centrifugal force to split pressurized slurry into fine light overflow and coarse heavy underflow.
Hydrodesulfurization
Hydrodesulfurization is a catalytic refining process that removes sulfur from petroleum fractions by reacting organosulfur compounds with hydrogen over sulfided molybdenum catalysts, letting refineries meet ultra-low-sulfur diesel limits.
Hydrodynamic cavitation
Hydrodynamic cavitation (HC) is the formation, growth, and implosive collapse of vapor bubbles where liquid passes through a constriction, producing extreme conditions used in wastewater treatment.
Hydrodynamic drag reduction coating
A hydrodynamic drag reduction coating is a surface treatment for hulls and underwater vehicles that lowers water friction, mainly by altering the turbulent boundary layer at the wall.
Hydrodynamic lubrication
Hydrodynamic lubrication is a regime in which a fluid film drawn between two moving surfaces fully separates them and carries the load, with a friction coefficient below 0.01.
Hydroelectric power in India
Hydroelectric power in India is electricity generated from the country's rivers, supplying about 10% of installed capacity with roughly 49,600 MW of large hydro in 2025.