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3.) Understanding the Inner Workings: How Hydraulic Cylinders Work
A hydraulic cylinder jack, often referred to as just "cylinder", is identical in nature to the commonly seen hydraulic cylinder on heavy equipment. They both provide, through pressurized hydraulic fluid, linear motion with high force. The difference is that this special cylinder is used like a jack to lift or pull a load. Unlike a permanently attached hydraulic cylinder, jack cylinders provide versatility through their ability to be placed in multiple positions and configurations.
What are the basic parts of a cylinder?
The basic cylinder parts are shown in the schematic illustration entitled Hydraulic Cylinder Jack Anatomy. These are: base, cylinder body, optional return spring, and plunger. A plunger differs from a piston rod only in name; a plunger's diameter is large in comparison to the cylinder bore. Also shown in the schematic but not labelled are the hydraulic fluid ports and the piston. Optional end fittings, such as high alloy steel saddles, are often retrofitted to the plunger. Some plungers are plain-end while others have male and/or female threads to accept a range of special attachments. Some plungers have center holes devoid of threads. Some cylinders have collar threads, carrying handles, and special provisions within the base called mounting holes to allow for various fixture arrangements. Other bases have a single, relatively large, mounting hole with internal threads.
Why are there two names for the same cylinder component?
There exists no industry standard nomenclature for cylinder construction; the terms below refer to the same cylinder part:
- Plunger is sometimes referred to as piston rod or ram. Plunger is the more correct in that its definition is generally taken to mean a piston whose rod diameter is large in comparison to the cylinder‘s inside diameter, or bore.
- Locking collar is sometimes referred to as locking nut. They are one in the same. Occasionally the term mechanical load holding is used.
- Collar thread is sometimes referred to as cylinder thread.
- Center hole cylinder is sometimes referred to as a hollow cylinder. They both refer to the fact that the cylinder contains a circular opening through the entire cylinder body.
What are the basic actions of a cylinder?
Essentially the cylinder's plunger extends and retracts with the application of fluid pressure. These two actions can be used to produce an array of pushing, pulling, and lifting applications.
What are the distinguishing characteristics of cylinders?
Profile refers to the retracted height of the cylinder body. Standard and low profiles are available. Standard profile cylinders have a retracted height approximating 1.3X the stroke. Low profile cylinders are suitable for those applications where minimal clearance is available. Strokes for low profile cylinders are necessarily limited.
High Duty Cycle
General purpose cylinders are limited to the number of cycles they can sustain before maintenance considerations become an important factor. High duty is generally considered as greater than 2,500 life time cycles. High duty cylinders (also known as industrial grade) are fabricated of rugged, resilient materials.
Body & Plunger Materials
Coated alloy steel is the standard cylinder body material. Chrome plated steel is the standard plunger material. Without comprising capacity, aluminum bodies and plungers provide the advantage of lighter weight, offer some corrosion resistance, and are non-sparking in hazardous environments. Aluminum is not recommended in high duty cycle (production) applications.
Cylinders are manufactured in load capacities ranging from 2 to 1,000 tons. Plunger force is produced by fluid pressure against the piston or bottom portion of the plunger. Because the effective area for pressure application is smaller by the area displaced by the plunger, the resulting capacity can be considerably less in the return stroke of double acting cylinders.
What are the different functional variations of cylinders?
Aside from the fact that there e