Hydraulic Press: Working

A hydraulic press can be understood as any machine using hydraulic pressure to compress something. Such presses can range from small hand jacks to large machines used for compressing scrap cars into tiny boxes or sheets. The main principle on which the hydraulic presses or jacks work is basically the Pascal's principle. The equation for which is:

F0/A0=F1/A1

wherein,

F0=Force Applied (to the fluid)
A0= Area (of cylinder)
A1= Area (of the second cylinder)
F1=Resultant Force

As per the given equation, F0 force is applied onto the fluid across an area A0 within a cylinder which is then transferred to another cylinder With area A1. This ultimately results in creating the final force as F1. This is so, as generally, the hydraulic fluid is non-compressible and thus, the pressure in one cylinder is equivalent to the pressure in other cylinder. Most of the hydraulic machines work on the same principle and so does the hydraulic press as well.

Hydraulic Tower Cranes

Tower crane refers to a kind of crane which which is a relatively stationery device with a movable base. Its anatomy is so, that a huge, static tower branches a horizontal beam or jib making an uneven form of alphabetical letter “T”.

Basically, the construction of tower cranes is segregated as per the mechanisms used in its manufacturing. A standard tower crane is actually constructed by assembling smaller supplementary crane while a self erecting tower crane has a hydraulic base hence it is a branch of hydraulic crane called hydraulic tower crane.

The hydraulic base of the hydraulic tower crane pushes the specific sections of the tower to the desired height, though the jib is attached using a secondary crane prior to starting the hydraulic mechanism.

Hydraulic tower cranes are often used for setting beams and huge building components at construction sites and for loading and unloading at shipping and transportation sites.

Diesel Effect: The Reasons and Preventions

At times rod seals in a hydraulic system start leaking or fail due to an effect called the 'diesel effect'. Technically, diesel effect occurs when the air within the hydraulic cylinder draws past the rod seals, diluting within the hydraulic fluid and exploding when pressurized. This whole process concludes to what we call the diesel effect. This aeration causes a number of problems in the hydraulic cylinder.

Hydraulic Cylinder and Diesel Effect

If a double-acting hydraulic cylinder withdraws due to the weight of its heaviness then the cylinder's rod side can ask for more volume of fluid than what the pump is actually supplying. In such a case, a negative pressure gets developed in hydraulic cylinder's rod side which eventually, draws air past rod seals within the cylinder. This is a persistent problem with the rod seals which are designed to retain high pressure fluid and abstain the air out. Now the result of such aeration is the dilution of air within the hydraulic fluid.

This aeration is undesirable as it results in overheating and reduction of lubrication. Moreover, the compression of air and oil leads to explosion thus, rendering the cylinder damaged by firing its seals. If noticed carefully, one can notice that 'diesel effect' is actually an alias name for the combustion process of a diesel engine.

Precautions

The problem of diesel effect can be handled smartly by keeping a regular check on the adjustment and operation of circuit protection devices. As the saying goes that a stitch in time saves nine, the faults in a hydraulic machine, or any other machine for that matter, if identified beforehand can save a great deal in terms of money, time and efforts.

Hydraulic System Life Span: Minimum and Maximum

While working with hydraulic systems, it is important to understand its anatomy in and out. Careless usage of a hydraulic machine can shorten down its potential life drastically.

Reasons for a shorter life span

The most common reason for a hydraulic system's deterioration is hydraulic fluid contamination. Inadequate efforts at removing contaminants from fluid or avoiding the replacement of hydraulic fluid until a severe fluid breakdown occurs, generally reasons the poor performance of system over a period of time.

Most often the contaminants enter the system in form of dust with metal or rubber besides, entrapped water and air too contaminate the fluid. In order to maintain clean and clear hydraulic fluid, it is wise to inspect the fluid samples regularly.

Fluid contamination can also be called “additive deterioration” as additives are the key source which provide the oil with certain specific characteristics. Since these additives are more vulnerable to chemical and physical changes, their deterioration can result into fluid breakdown. Fluid deterioration often occurs due to high temperatures hence, it is advised to keep the fluid operating temperatures well below 60 degree Celsius (140 degree Fahrenheit). Now-a-days most of the hydraulic power units are laced with heat changers, temperature controls and over-temperature.

Solutions to elongate the life span

A hydraulic system's life can be maximized to the fullest by keeping a regular check over the clarity of hydraulic fluid. The two major things which needs to be looked after are fluid contaminants and the chemical composition of fluid.

The best way to inspect fluid is sampling the fluid first and then analyze it. It gives a fair amount of idea as to whether the fluids or filters needs to be replaced or not. Such analysis can also help in determining the exact viscosity of the fluid as well as detecting the contaminants in it like water or other foreign particles. Besides, it can also prove helpful in calculating the chemical composition of the fluid to know whether it can still be used further or not.

A thoughtful evaluation of contaminants and its source within the hydraulic system is extremely important to avoid them in future as well as elongate the working life of a hydraulic system to the utmost.

Controlling Water Hammer in Hydraulics

At times hydraulic machineries pose the problem of high vibration in pumps, lines and tanks. This problem of constant vibration is termed as water hammer. The concept of water hammer is discussed in detail below:

Water Hammer: The Term
As the term itself suggests, water hammer refers to the banging sound of fluid through the pipe which is created due to the pressure wave, a by product of varying fluid velocity, within the pipe. When the banging effect heightens, it almost sounds as if the pipe is being hammered, thus, the term water hammer was coined to refer the problem. The common traits of this problem are high noise levels, broken pipes and vibrations.

Technical Cause of Water Hammering
Technically, when a moving column of hydraulic fluid hits a solid boundary, its velocity drops down to zero and the fluid column looses its strength to absorb the (kinetic) energy affiliated with its motion. Though as the fluid is incompressible, the deformation henceforth is smaller making the fluid accumulate energy like a spring. The level of pressure rise can be calculated as:

Pr = P + u p c

where “P” refers to initial pressure, “u” and “p” refer to initial fluid velocity and density while “c” represents the speed of sound within the fluid.

Solution
Certain damping devices like accumulators can be used to curb down the noise problem. However, as per the above equation, fluid velocity is the only variable which can be manipulated to address the main problem. The lower the fluid column velocity would be, the lower the subsequent pressure rise would be, hence resultantly, lower sound effect.

Hydraulic Laws: The Underestimated Fundamentals

Most often we tend to overlook the very basic laws of hydraulic system while repairing or troubleshooting a problem with it. Like every other scientific machinery, hydraulic machines too have certain cardinal laws which has to be kept in mind while dealing with them. Let's have a look at some of these laws:

Law 1: Hydraulic pumps are responsible for creating flow and not pressure.

Law 2: The resistance to a running flow creates pressure.

Law 3: Flow decides the actuator speed.

Law 4: Pressure decides the actuator force.

Law 5: Fluid while in pressure takes way of the least resistance.

Law 6: Heat is generated in case the fluid transfers from a high pressure area to a low pressure area (pressure drop) without performing useful work.

The importance of these rules or laws are often underestimated but the fact remains that these are the core fundamentals which form the very platform for the whole hydraulic concept. Hence, it is only essential to recognize the significance of these laws and always bring them in practice.

Repairing a Hydraulic Component

As is the case with every machinery, repairing is done to make a particular faulty part as good as new. With hydraulic machinery too, repairing or reworking is aimed at making the entire machinery work smoothly and in sync with each and every part. Most often, a simple repair of a defective part saves the wrath of changing the entire equipment. Since buying a new hydraulic pump, motor or cylinder would prove a costly deal, repairing them can indeed be a sensible option.

If we go by the absolute calculations then it is quite obvious that the more the cost of new component would be, the more cost effective the repairs would prove. Though the cost of a hydraulic repair involves some crucial factors like:

-Intensity of damage or wear and tear of the component

-Facilities and expertise available to tackle the damage

-The repair techniques used to deal with the wear and tear

Generally the processes used for repairing hydraulic parts are honing, lapping, machining, grinding and hard-chrome plating. A skillful application of such processes can help a great deal in reducing the need of new hydraulic components.

Considering Aftermarket Components
In most cases, the hydraulic repair cost can be curbed even further by the using a non-genuine, aftermarket hydraulic part. These are easily available in market and are generally, manufactured by the niche manufacturers in varied qualities ranging from poor to excellent. Though, these aftermarket components are at times manufactured by the genuine part makers too, hence, one can find a number of non-genuine components to use while repairing a hydraulic equipment.

However, the most important thing to consider while using an aftermarket hydraulic component is the quality of that component. A non-genuine part with a dicey quality can cost a lot more than the actual price while a decent quality component can make you save money on the repair cost and prove an economical choice in long run. An aftermarket part should be used only when you are sure that:

-It is a quality proven component with great performance and service life

-It offers a warranty period

It is wise to buy a aftermarket part only when it carries a known name and the supplier is also ready to back it, otherwise, it is bound to be a risky deal.