cylinders and what to look for

A Simple Introduction to

CYLINDERS How to identify the problem and find results that last.

A Publication of Hydraulic Training Associates. llc.

CYLINDERS

Why they fail and what to look for.

"Flow Makes It Go" 2

CYLINDERS


In this book we will be discussing the trials and tribulations found in some instances with cylinders. This is not a conclusive understanding nor is it intended to be, rather a small glimpse of what to expect in some cases. The actuator can be thought of as the business end of a hydraulic circuit. It provides the output motion and provides and develops the force or torque the system requires to do the work. The job to be done and the speed, force and torque requirements will determine the necessary size of the hydraulic actuator to be used. On applications where there is a straight line or linear motion a hydraulic cylinder is used. Applications requiring rotary motion use a hydraulic motor.

Single Acting A single acting cylinder is pressurized on one end only. The opposite end is vented to the tank or atmosphere. They are designed so that the load or a device, such as an internal spring, retracts them


Repairing a hydraulic component involves reworking or replacing all of the parts necessary to return the component to 'as new' condition, in terms of performance and expected service life. In many cases, repairing a pump, motor or cylinder can result in significant savings when compared with the cost of purchasing a new one. The economics of proceeding with any repair is ultimately dependent on the cost of the repair, relative to the cost of a new component. As a rule, the more expensive the new component is in absolute dollar terms, the more likely it is that a repair will be cost effective. The cost of a hydraulic repair is determined by a number of factors including: Extent of wear or damage to the component Facilities and expertise of the repair shop Repair techniques employed


CYLINDERS

Double Acting The double acting cylinder is the most common cylinder used in industrial and mobile hydraulics. Pressure can be applied to either port, giving power in both directions. These cylinders are also classified as differential cylinders because of their unequal exposed areas during extend and retract. The area of the rod reduces the effective area of the piston during retraction.


Cylinders fail from either prolonged use, debris in the system, failure of seals, or overpressure. Miss-alignment and sometimes failure of outside parts such as pins or bushings will cause damage to the cylinders as well. Identify what caused the failure so as to prevent a pre-mature reoccurrence. A micro switch coming loose and repositioning itself caused a Lead Mining Plant to shut down one of their filter presses because the kept bending cylinders and replacing them before following this procedure. Once I was able to get them to observe what may have caused the problem rather then fixing the symptom, they stopped bending rods.

CYLINDERS



CYLINDERS


Once apart, are you sure of what you’re looking at? Are you seeing the entire picture or are you simply resealing to get the cylinder back on the equipment? A typical process used to expedite equipment use, unfortunately this tends to be one of the greatest causes for reoccurring failures. Examine completely all parts of the cylinder, measure the gland, piston, inside of the barrel in four places (to assure that it has not ballooned due to over-pressurization). Be looking for burrs, cracks, pitting, chrome scrapped off, seals that may have been nipped or broken. Set the rod into a set of machinists blocks and measure for straightness with a dial caliper. Look at the pin holes and threads of all parts. Each of these can be a cause or a symptom of something greater causing the failure.


CYLINDERS


Any body can disassemble a cylinder. Do you know how to re-assemble it without tearing or ripping the seals on the re-assembly?

Here is a case where the pressure was too great for the application. This type of cylinder is used typically on steering applications. A lower pressure system, yet someone used this cylinder on a higher pressures system because if fit in the application.


CYLINDERS


Determining which the proper use of a cylinder is will help to reduce down time and unfortunate disasters such as this.

Proper cleaning and inspection is imperative before resealing any cylinder. Remove all debris and wipe down the cylinder.


CYLINDERS


Telescopic cylinders are the most precarious because so much happens with a telescopic that is neglected upon inspections.

Much of the time while the equipment is in the upright position, vibration and stress due to pressure wear on the sealing areas of the cylinder.


CYLINDERS


When a hydraulic component is repaired, there are usually some parts that can be successfully re-used after they have been reworked using processes such as machining, honing, lapping, grinding and hard-chrome plating. The skilled application of these techniques can reduce the number of new parts required, reducing repair costs.


CYLINDERS



Many Seal Companies available: Contact your local seal house for information on design, engineering, and usages of proper seals for your cylinders.

“Trust but Verify.”

- President Ronald Regan


FOR MORE INFORMATION ON

CYLINDERS, SEALS AND

TROUBLESHOOTING CONTACT

OUR OFFICE TODAY 866-432-9771 e-mail: [email protected] web: www.htahydralics.com

A Publication of Hydraulic Training Associates, llc.

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cylinders and what to look for

Education

hydraulic cylinder

common cylinder

type of cylinder

hydraulic repair

hydraulic component

hydraulic motor

hydraulic actuator

telescopic cylinders