Hydraulic cylinder is a linear actuator which extend forward and retract backward to transfer power by pressurized hydraulic fluid. Hydraulic cylinder is widely used in every hydraulic system in industrial or automobile applications. Basic hydraulic pneumatic system components Types of hydraulic pump Hydraulic cylinder speed calculator Hydraulic directional control valve types Basic pneumatic system
Hydraulic cylinder are consist of two main elements is barrel and piston attached piston rod. There are also other elements like Rod end port, cap end port, piston seal, tie rod, O-ring, Rod seal etc.Basic hydraulic pneumatic components directional control valve types pump cylinder speed calculator
Barrel: Barrel is a seamless forged tube that is developed with high quality surface inside.
Base: Base is like a flange that is connected with barrel and screwed with it.
Cylinder head: Cylinder head is a part that contain wiper seal, wiper seal and rod end port.
Piston: Piston that separates the cylinder in two chambers. Piston has some piston seal, guide rings in outer surface that prevent passing oil between two chambers.
Piston rod: Usually piston rod mad with hard chrome-Plated cold-rolled steel. It is mounted with the piston and directly handle the load.
Port: Fluid flow enter into the cylinder and and go out from the cylinder.
Hydraulic seal: Hydraulic seal is made from Polyurethane(PU),Polytetrafluoroethylene (PTFE) and other high quality material. Hydraulic seals prevent oil leakage and contaminants from outside weather.
Types of hydraulic cylinder
Single acting hydraulic cylinder
In a Single acting cylinder, fluid pressure acts only the single side of the piston and on the other side of the piston move backward by mechanical load, spring and compressed air. When fluid enters and act to the piston end to developed pressure then it creates linear motion and extend the cylinder. If control valve releases the pressure then the cylinder moves backward this is how single acting cylinders works. Single acting cylinder is most commonly used in hydraulic ram, reciprocating engines etc.
Double acting hydraulic cylinder
In a double acting cylinder fluid acts in both side of the piston and can create linear motion in two directions. During the directional control valve coil energized (Coil A) the fluid enters to the inlet port that acting to the blind end of the piston and moves forward while the fluid out to the tank through rod end port (Cylinder extend). If the directional control valve energized again (Coil B) the flow of fluid changes the direction and fluid enters to the rod end port and out to the blind end port thus piston move backward (Cylinder retract).
Hydraulic cylinder calculation
Cylinder calculation is the most important things before selecting it for the hydraulic system.
The distance between piston rod fully extend and fully retract length is the stroke of the cylinder.
Hydraulic cylinder speed calculation
A cylinder Bore is 100mm stroke is 1000mm rod diameter is 80mm and hydraulic pump flow is 5 Lpm. Now calculate cylinder forward speed and retract speed?
5 Litter oil filling time is = 1 Min =60 sec
1 Litter oil filling time is = 60/5 = 12 Sec
7.9 Litter oil filling time is = 7.9×12 Sec = 94.8 Sec
2.9 Litter oil filling time is = 2.9×12 Sec = 34.8 Sec
Forward speed of cylinder will be
1000mm opening time = 94.8 sec
Opening per 1 sec = 1000/94.8 sec = 10.54 mm/Sec
Retract speed of cylinder will be
1000mm opening time = 34.8 sec
Opening per 1 sec = 1000/34.8 sec = 28.73 mm/Sec