 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 exists an almost endless array of sizes, profiles, and capacities supplied by numerous manufacturers, cylinders fall into two basic operational categories:
The most common cylinder configuration is single acting (see the illustration). Pressurized fluid is routed to only one side of the piston causing extension of the plunger. When the hydraulic fluid is allowed to exhaust through the port, the weight of the load retracts the plunger. An optionally supplied internal spring can also provide forced retraction.
Spring return retraction of single-acting cylinder
To retract, small cylinders are outfitted with steel springs to pull the plunger back once the oil pressure is released. This is called "spring return".
Load return retraction of single-acting cylinder
Larger cylinders retract through the weight of the load pushing the plunger back. This is called "load return."
Routing pressurized fluid through two ports provides hydraulic action bilaterally to the piston. This requires the connection of a fluid circuit to the cylinder in order to accommodate the entering and leaving fluid streams. Double acting cylinders are used in applications that require force to both push and pull.
What are some of the specialized parts of a cylinder?
Most cylinders are equipped with some, if not all, of the following specialized components:
- The plunger wiper located at the cylinder top and plunger interface cleans the plunger during retraction and thereby reduces hydraulic fluid contamination and minimizes seal-damaging foreign matter.
- A stop ring located at the plunger to piston interface, or in some models at the top dead cylinder bore interior, prevents over-extension of the plunger and absorbs unintended lateral forces caused by off-center load application.
- Side bearings located at the interior top and bottom of the plunger stroke support the plunger against side forces that can be produced when eccentric (off-center) loads are encountered.
What other equipment is used with a cylinder?
Depending on the application, a host of 