Hydraulic Cylinders: How Do They Work?
If you’re curious about how hydraulic cylinders work, then you could find this post to be interesting. Let’s take a look at these powerful components that make it possible to move and lift the heaviest of items with ease.
You may not have ever considered this before, but what do you think deploys those huge wheels that aircraft need to land? They are put away tidily throughout a flight, and then when they’re approaching Heathrow, out they pop and all at the pilot’s press of a button.
Landing gear is operated through a hydraulic system. As with any hydraulic system, there are pipes, cylinders and of course hydraulic fluid. The fundamentals of this are the same as with any hydraulic system. When force is applied at one point, it is transmitted to another through the use of incompressible fluid.
Working of Hydraulic Cylinders
Hydraulic cylinders mostly come in parallel pairs that are of differing diameters and are connected by a pipe. The cylinders will be at right angle to the pipe. This arrangement is then filled with a hydraulic fluid such as oil until the cylinders are partly filled.
The space that is left in the hydraulic cylinders will enable the pistons to operate. In one cylinder, the piston will be smaller than in the other. Fluid will be pushed into the chamber of the small piston and when force is applied, it will push the fluid into the chamber of the big piston as it will be incompressible fluid. This will then move the big piston. Due to the difference in size, the effect of the small piston’s movement will be multiplied. So for example if a small piston has a downward force applied to it of 100 lbs – the force on the big piston will be 900 lbs.
Hydraulic cylinders remove the need for a rigid structure when it comes to transferring force between two different points. This can be used to the hydraulic system’s designer’s benefit and a number of twists and turns can be added to the system. For example, there might be a space constraint. Using the different cylinders at different sizes, it’s possible to create a system that will pull, push or even lift heavy weights.
Hydraulic Cylinder Parts
Although the hydraulic systems that are used in our everyday life are not built with cylinders quite as basic as what’s described above, they are fairly similar. Let’s look at the different components involved:
- Cylinder barrel
- Piston rod
- Cylinder bottom (Cap)
- Piston
- Cylinder head
- Cylinder bottom connection
- Rod glands
- Seals
- Cushions
Types of Hydraulic Cylinders
There are two different main types of hydraulic cylinders used. The tie rod type of cylinders and the welded body type. The former are used when there is a need for heavy-duty industrial or commercial use. Some are small bore and others large bore. The welded body cylinder type has no steel rods in it. The top of the barrel of the cylinder is welded directly onto the object that is expected and designed to move. Although these cylinders are small in size, they are used in a surprisingly large number of different machines. In some cases it’s necessary to use a telescoping hydraulic cylinder where the piston rod will retract into the barrel of the cylinder.
Hydraulic power has really evolved over the last 50 years or so. Much of the progress has come from the aeronautical industry, surprisingly. Although hydraulics have been used since before the time of the first recorded history, it’s only now that they have really come of age and have made such a tremendous difference to us in so many fields.