Controlling the speed of an air cylinder

The speed at which the piston of the air cylinder moves is controlled by the amount of air you let flow in and out of the air cylinder. You do this with the help of a throttle valve (also called a speed control valve). This valve works as a tap that can regulate the airflow.

Usually you place the valve directly at the connections of the cylinder. You can also place it between the hose or throttle the outgoing air via dampers on the valve. The air can start to flow and you regulate its speed by squeezing the outflowing air (this is called throttling in the vent). By slowing down the air leaving the cylinder, a slight back pressure is created. This back pressure ensures that the movement remains controlled and smooth, rather than jerky. 

• Less air = Cylinder delayed
• More air     = Cylinder accelerated

Usually a throttling valve or speed control valve with a built-in check valve is chosen. This valve allows the compressed air to enter the cylinder and smother it out without throttling (meaning that the cylinder moves in the opposite direction and the air from the cylinder chamber comes out through the same valve.

 

Sometimes it is also decided to throttle the incoming air outside the outgoing air. This is often done when the cylinder has to move different forces in the stroke.

 

Suppose the cylinder pushes a heavy valve up via a hinge. The upward movement is heavy and provides a lot of resistance, but halfway through the lid almost falls into its final position. If you were to throttle only the outgoing air, the cylinder could accelerate due to the suddenly reduced resistance, causing the valve to end up too hard. By also throttling the incoming air, you prevent acceleration and the movement remains controlled and even over the entire stroke.

 

Controlling the power of an air cylinder

 

The force you can make the air cylinder deliver depends on two factors: the pressure of the compressed air and the surface of the piston. So the pressure determines the force and the throttling regulates the speed. When the pressure is increased, the speed also increases because more liters of air are sent through the throttle valve. Therefore, always adjust the cylinder to pressure first and then to speed with the throttle valves!

 

Often the pressure in the cylinder is adjusted with 1 pressure regulator, which is set to the minimum pressure that the cylinder needs. Usually this is 6 bar. If you have multiple cylinders, you adjust the pressure to the cylinder that needs the most pressure. If you want to use a different amount of pressure for the input and output stroke, you can place a pressure regulator between the valve and the inlet of the cylinder. Please note that you will need a pressure regulator with a backow or a return function,0 these can be ordered separately.

 

Adjusting pressure

• The easiest way to control the force is to adjust the number of Bar of the compressed air. You do this with a pressure regulator that you put in front of the valve in the air supply.

Cylinder size

• The power also depends on how big the cylinder is. A larger cylinder or in other words, a cylinder with a larger piston diameter has a larger surface area and can therefore deliver more force at the same pressure than a smaller cylinder. In short: Pressure regulates the force during work. The diameter of the cylinder determines the maximum force.

 

• Force x Pressure = Area

 

 

Back to knowledge base