Actuators are the components that turn fluid-system energy into physical machine movement. Cylinders produce linear motion, while rotary actuators and hydraulic motors produce rotational movement. Manifolds control the fluid paths that command these devices.
The relationship between pressure, flow, actuator size, valve capacity, tubing, and manifold passage geometry determines how much force an actuator can produce and how quickly it can move.
Linear Motion
How Fluid-Powered Cylinders Work
A cylinder contains a piston that separates internal chambers. Applying fluid pressure to one side of the piston creates force and moves the piston and rod.
A directional valve determines which chamber receives pressure and where fluid from the opposite chamber travels.
Manifold passages allow the supply, return, exhaust, pilot, and control paths for several actuators to be organized into one compact assembly.
Hydraulic Actuation
Hydraulic Cylinders and Actuators
Hydraulic cylinders use pressurized liquid to create controlled linear force.
The legacy industrial resources include hydraulic cylinder manufacturers as well as information on hydraulic actuators.
Hydraulic actuators can be used for lifting, pressing, clamping, positioning, steering, tooling, material handling, and many other industrial and mobile functions.
Manifold pressure-control and directional valves determine how hydraulic flow reaches these actuators.
Pneumatic Actuation
Pneumatic Cylinders
Pneumatic cylinders use compressed air rather than hydraulic liquid.
They are frequently used for high-cycle machine movements such as gripping, clamping, sorting, ejecting, indexing, positioning, and packaging.
Pneumatic manifolds can group several directional valves around shared air-supply and exhaust passages, allowing many cylinders to be controlled from one assembly.
Explore Pneumatic Manifolds →Force
Pressure, Piston Area and Actuator Force
Cylinder force depends on the pressure acting against the effective piston area.
Increasing pressure increases theoretical force, while increasing piston area allows more force to be produced at the same pressure.
Actual machine performance can also be influenced by friction, mechanical loading, seal condition, pressure loss, mounting geometry, and other system factors.
Speed
Flow Controls Actuator Speed
While pressure is closely associated with actuator force, flow rate influences how quickly the actuator changes position.
A cylinder cannot move rapidly if its valve, manifold passage, fitting, hose, or tubing restricts the required fluid volume.
Return or exhaust restrictions can also slow movement because fluid must leave the opposite chamber as the piston moves.
Engineering
Actuator and Manifold Sizing Factors
Sealing
Cylinder Seals and Internal Leakage
Cylinders contain seals around pistons, rods, glands, and other interfaces.
Worn or damaged seals can allow internal leakage, external leakage, pressure loss, or reduced holding capability.
When troubleshooting an actuator problem, it is important to determine whether pressure is being lost inside the cylinder or elsewhere in the manifold circuit.
Seals, O-Rings & Gaskets →Troubleshooting
Diagnosing Slow or Weak Actuators
Slow movement can result from restricted flow, low pump or compressor output, undersized valves, blocked filters, small tubing, excessive exhaust restriction, or internal actuator leakage.
Weak force can result from low pressure, excessive load, damaged seals, incorrect pressure-control settings, or mechanical binding.
Measuring pressure near the manifold and actuator can help separate supply problems from problems inside the actuator itself.