What is Fluid Power?

What is a Manifold?

When the phrase "hydraulic valve manifold" is mentioned, most people immediately think automotive manifold. "Hydraulic valve" doesn't register, but manifold does, and naturally so, since most of us associate manifolds with automotive engines. Hydraulic valve manifolds function in theory, the same as automotive manifolds. Both are part of distribution systems. In the automobile system, gasoline is pumped to the carburetor, which is mounted on the intake manifold. The gasoline/air mixture supplied by the carburetor is then distributed to the engine's cylinders. While in the cylinders, this gasoline vapor goes through a combustion process that ultimately supplies the horsepower to propel the vehicle. The exhaust manifold collects exhaust from this process and directs it from the vehicle.

Hydraulic valve manifolds perform the same functions as automotive manifolds only our manifolds are distributing pressurized hydraulic oil. Valves are mounted on our manifolds and are used to distribute the oil in the manifold. The oil is then directed from the manifold through tubing to a work device, normally a cylinder or hydraulic motor. Depending on the work device, different types of mechanical work can be performed in a linear or rotational manner.

The roller coaster is a typical application in which hydraulic power is converted into rotational mechanical torque by attaching a gear to the hydraulic motor shaft, which in turn drives the chain to which the roller coaster cars are linked. Now the cars have a means to reach the top of the first hill, providing the hydraulic motor is turning in the correct direction! Hence, the importance of hydraulic oil being directed (through hydraulic valves) in the proper direction.

Exhaust oil is returned to the manifold though tubing where it is consolidated, and returned to the holding tank (reservoir) where it will be re-circulated. A major difference between automotive and hydraulic systems is their source of "power." The engine effectively achieves horsepower through a controlled explosion internal to the engine. Hydraulic power is generated by a pump located in or near the reservoir. This power is ultimately discharged at the work device by pushing an object in a linear direction (hydraulic cylinder), or pushing against motor vanes, generating a rotational action.

Fluid power is energy transmitted and controlled through a pressurized fluid, either liquid or gas. The term fluid power applies to both hydraulics and pneumatics. Hydraulics use pressurized liquid-oil or water; pneumatics use compressed air. Fluid power can be effectively combined with other technologies through the use of sensors, transducers and microprocessors.

Fluid Power Fluid power systems provide many user benefits, including:

• Multiplication and variation of force. Linear or rotary force can be multiplied from a fraction of an ounce to several hundred tons of output.



• Easy, accurate control. You can start, stop, accelerate, decelerate, reverse or position large forces with great accuracy. Analog (infinitely variable) and digital (on/off) control are possible. Instantly reversible motion—within less than half a revolution—can be achieved.



• Multi-function control. A single hydraulic pump or air compressor can provide power and control for numerous machines or machine functions when combined with fluid power manifolds and valves.



• High horsepower, low weight ratio. Pneumatic components are compact and lightweight. You can hold a five horsepower hydraulic motor in the palm of your hand.



• Low speed torque. Unlike electric motors, air or hydraulic motors can produce large amounts of torque (twisting force) while operating at low speeds. Some hydraulic and air motors can even maintain torque at zero speed without overheating.



• Constant force or torque, a unique fluid power advantage.



• Safety in hazardous environments. Fluid power can be used in mines, chemical plants, near explosives and in paint applications because it is inherently spark–free and can tolerate high temperatures (120-150 degrees Fahrenheit for hydraulics and up to 250 degrees Fahrenheit for pneumatics).



• Established standards and engineering. The fluid power industry has established design and performance standards for hydraulic and pneumatic products through NFPA, the National Fluid Power Association; ANSI, the American National Standards Institute; and ISO, the International Organization for Standardization.

Fluid Power Applications

• Mobile: Fluid power is used to transport, excavate and lift materials, as well as control or power mobile equipment. End–use industries include construction, agriculture, marine and the military. Applications include backhoes, graders, tractors, truck brakes and suspensions, spreaders, and highway maintenance vehicles.



• Industrial: Fluid power is used to provide power transmission and motion control for the machines of industry. End–use industries range from plastics to paper production. Applications include metalworking equipment, controllers, automated manipulators, material handling and assembly equipment.



• Aerospace: Fluid power is used for both commercial and military aircraft, spacecraft and related support equipment. Applications include landing gear, brakes, flight controls, motor controls and cargo loading equipment.

How Fluid Power Works

Pascal's Law expresses the central concept of fluid power: "Pressure exerted by a confined fluid acts undiminished, equally in all directions."

1. An input force of 10 pounds (44.8N) on a one-square-inch (6.45 cm² piston).

2. Develops a pressure of 10 pounds per square inch (psi 68.95 kN/m²) throughout the container.

3. This pressure will support a 100 pound (444.8N) weight if this is a 10-square-inch piston.

4. The forces are proportional to the piston areas.

What is Fluid Power was supplied courtesy of the National Fluid Power Association.

Oil under pressure is an awesome source of power, Hydraulic Power. Its primary mechanical advantage is its size–to–horsepower ratio. Surprisingly small components deliver impressive horsepower. Many different components are required to develop a hydraulic system. Daman Products is engaged in the manufacture of manifolds—hydraulic valve manifolds. These products are essentially distribution blocks on which hydraulic valves are mounted. Our products are typically made from aluminum or ductile iron.

For information on Hydraulics, see the NFPA Web site.