What is a hydraulic cylinder and how are they used on excavators?

Hydraulic cylinders are used effectively in a variety of applications to move heavy loads. This is because of their ability to generate large amounts of force using pressurised fluid, with relatively small amounts of input power.

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Different applications of hydraulic cylinders.

Some common applications for hydraulic cylinders include:

• Construction: used in plant and earth-moving equipment, such as excavators and bulldozers, to power the movement of the boom, dipper and bucket cylinders . Tracking the excavator back & forth.

• Manufacturing: used in production and processing equipment, such as stamping and pressing, to apply large amounts of force to shape or cut materials.

• Agriculture: used in farming equipment and machinery for services such as transportation, planting, feeding, drilling, cultivation and harvesting.

• Food and Beverage: used in wide variety of equipment to process and package food and drinks.

• Automotive: to power the brakes, steering and suspension systems in certain vehicles.

• Aerospace: used in aircraft to power the movement of the flaps, landing gear, airstairs and other control surfaces.

How do they work?

Hydraulic cylinders in an excavator work by using pressurised hydraulic fluid to generate a force that can be used to manoeuvre the excavator and move the boom, dipper and bucket. The control valve is used to control the flow of fluid into the cylinder, allowing the operator to move the boom, dipper and bucket with precision.

Typical cylinders found in Excavators & Mini-Excavators.

There are different types of cylinders found on excavators and mini excavators, each with its very own specific function.

1. Bucket cylinder: These cylinders are used to power the movement of the bucket, that is located on the end of the dipper arm. Bucket cylinders are typically smaller than boom cylinders and are used to move the bucket and to control its angle during excavation.

2. Boom cylinder: These cylinders are used to power the movement of the main boom, up & down. Boom cylinders are typically larger and more powerful and can generate significant amounts of tare out force to move the boom when working.

3. Dipper cylinder: The Dipper arm cylinder, also known as the stick or crowd it is used to power the movement of the arm which carries the bucket.

4. Rotary Unions: This unit is used transfer fluids from the excavator to the undercarriage of the machine. This allows the operator to change the direction the excavator is facing, which is important for manoeuvring the bucket in different directions or for dumping material.

5. Swing cylinder: A swing cylinder also known as a slew cylinder, is a hydraulic cylinder that is used in excavators to offset the upper part, of the boom about a vertical axis. This allows the operator to change direction, which is important for manoeuvring the machine in tight spaces or when digging in different directions.

6. Track Adjuster: The track adjuster is typically located in the undercarriage of the tracks and consists of a hydraulic cylinder that is connected to the track frame. When the cylinder is extended by pumping grease into the cylinder it adjusts the tension in the tracks.

7. Dozer: A dozer cylinder, also known as a blade cylinder, is used on mini excavator to raise and lower the dozer blade. The dozer blade is used to push or move materials, such as dirt, sand and helps in assisting the stability of the excavator.

8. Vari Width cylinder: This cylinder is fitted in the undercarriage to move the tracks in & out. On smaller excavators, this helps to increase the stability and allows the excavator to manoeuvre through narrow gaps greater than 900mm.

FPE Seals provide aftermarket replacement seal kits at OEM quality, for the hydraulic cylinders on an excavator, for 1000's of leading plant and engineering brand's equipment models.

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