Understandably when it comes to making the correct selection for your application needs it can be a little confusing so this guide takes a closer look at a range of hydraulic cylinder types to help you to make the right choice.
Hydraulic cylinders, sometimes known as jacks or rams, are devices that can make use of the pressure generated in a hydraulic system in order to move a load. They are typically moved with the use of pressurised hydraulic fluid such as hydraulic oil and offer mounting attachments to connect the cylinder to different objects or other machines.
There are many different applications for a hydraulic cylinder such as being used in forklifts, mining equipment, or trucks. The cylinder is one of the four main components of a hydraulic system that is responsible for creating movement. This is why it’s usually referred to as the “muscle” of a hydraulic system.
Different Types of Hydraulic Cylinders
There are a number of hydraulic cylinder types that are designed for different purposes. Consider the following points to choose the best hydraulic cylinder for your needs
- Single acting hydraulic cylinders only operate in a single direction. The plunger is moved in a single direction and the weight of the load or a spring helps to retract it back into place.
- Double acting hydraulic cylinders use hydraulics to extend and retract the plunger. It requires two connections; one where the hydraulic fluid is used to extend the plunger, and the other is used to retract it.
- Low height hydraulic cylinders, also known as pancake cylinders, have a much lower profile and are designed for confined spaces.
- Hollow plunger cylinders have a threaded collar that can be used for attaching various accessories. This allows the hydraulic cylinder to be used for both push and pull applications.
- High tonnage cylinders are typically designed as double acting hydraulic cylinders with a higher weight tolerance of up to 1,000 tons. These cylinders are made specifically for heavy lifting.
- Telescopic hydraulic cylinders reach further than typical telescoping cylinders by using multiple plungers referred to as stages. These can also be low height or double acting.
In some areas, a hydraulic cylinder may be referred to as a hydraulic ram. These names are interchangeable.
Single Acting Hydraulic Cylinders
A single acting hydraulic cylinder operates in a single direction. It often has a single port and uses gravity or a spring to retract the plunger after it has been used. These can easily be controlled with components such as a control valve to control the flow rate. Single acting hydraulic cylinders have a number of applications. They can commonly be found in factory automation settings like handling packages or materials.
The term single acting refers to the action of the hydraulic cylinder. As such, it can also be combined with low height, hollow plunger, or even telescope 2 stage and 3 stage hydraulic cylinders. While simple, they are reliable, easy to install, and cost-effective for many applications.
Double Acting Hydraulic Cylinders
A double acting hydraulic cylinder typically has two inputs. This is because it uses hydraulics to push and pull the plunger, making it effective in situations where rapid or controlled retraction is needed in addition to extension. Two single acting hydraulic cylinders could technically perform the same function, but one double acting hydraulic cylinder is more cost effective and efficient in terms of space.
When it comes to double acting vs single acting hydraulic cylinders, the application they are used in must be considered. In most cases, double acting is required when there is no other external force that can retract the plunger. It can also be used where a strong or controlled force is required in both directions. Some applications include opening and closing gates or pushing and pulling items off a conveyor belt.
Much like single acting, double acting is a term that describes the internal mechanism. As such, you can often find double acting hydraulic cylinders that are built for high tonnage or have increased range with a telescopic mechanism.
Low Height Hydraulic Cylinders
Low height hydraulic cylinders are often used when space is a concern or if portability is needed. While they perform similarly to standard single acting and double acting hydraulic cylinders, they are normally rated at a lower tonnage due to their size. A low hydraulic cylinder should be considered when there isn’t enough clearance to install a larger one, or if the task doesn’t require a high amount of force. Due to the size of a low profile hydraulic cylinder, they are typically only offered as single acting.
Hollow Plunger Cylinders
Hollow plunger cylinders, sometimes referred to as hollow plunger cylinders, are often used for push and pull configurations. This is thanks to the threaded collar inside the plunger, allowing for attachments like fixing rods to be connected to the hydraulic system. For more control or force, a hollow plunger cylinder can be double acting as well. This also allows for the range to be extended, but it’s recommended to use telescopic hydraulic cylinders in cases where a longer stroke length is required. These are commonly seen in pressing and punching applications or used for crimping operations.
High Tonnage Cylinders
High tonnage cylinders are mainly used in situations where heavy lifting is required. Hydraulic lifting cylinders are usually designed with much higher weight tolerances up or beyond 1,000 tonnes. They also provide more side-load protection and help to maintain stability. These can come in both single acting and double acting varieties as well. For push and pull applications, a high tonnage cylinder may also have a hollow plunger.
Telescopic Hydraulic Cylinders
Telescopic hydraulic cylinders are used in applications where more length is required. They are usually categorised as 2 stage or 3 stage hydraulic cylinders and can be both single acting or double acting. Since their retracted length is no more than a regular hydraulic cylinder, they’re also great for saving space in confined applications. Due to the surface area and size of the individual cylinders, the initial extension produces the most force. The more stages the telescopic cylinder has, the more force it can produce.
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