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To ensure the smooth running of your fluid hydraulic power systems, it’s critical to schedule consistent maintenance of cylinders. Here are five hints on getting this right:
Regular inspections. Check whether the rod has any pitting, corrosion or uneven wear. Uneven wear could signal an impending disaster for the entire hydraulic system. Corrosion may indicate too much moisture either in the fluid itself or ambient moisture. It could also speed up wear on seals. Pitting can also lead to seal damage and can occur as a result of corrosion. There is plenty to watch for.
If you find that there is uneven wear on your rod, it is most likely caused by misalignment. If there is a load on one side only, it’s going to accelerate the wearing of the seals, bearing and of course, the rod itself. In almost all cases it’s possible to polish or re-chrome a rod that’s been damaged. If it’s not possible to refinish it to repair it, then a new one can be manufactured by a cylinder repair shop. Prior to reinstalling, check that the causal problem has been remedied, or you’ll find yourself needing to pass through the same process.
Cylinder rotation. If it’s critical that there is no downtime, keep a full set of cylinder spares that can be rotated regularly. You will retain fresh cylinders, even though you will be a high risk of particle contamination. When a cylinder is removed from service, inspect it and give it maintenance as required.
Once dissembled, replace seals as they are normally very affordable. You can then look for clues on how the rest of your hydraulic circuit is by inspecting the inside the cylinder interior. Look for varnish, and if you find it you know that your oil is running too hot and may need to be addressed.
A visual inspection of the piston and cap will give you an idea of whether the cylinder has trapped particles. If it’s pitted like somebody has been attacking it with an ice pick, then there’s no doubt that a piece of metal has been banging around in there for some time. If it’s reached your cylinder, then it’s already been elsewhere in the system.
Check lube oil system. If you have pneumatic cylinders, there is a need for a source of lubrication. Check whether there is enough oil in the associated reservoir. You may have a full reservoir of oil, but that doesn’t guarantee that the system is working. You may need to hook up a blow gun and a white paper towel to check. If you find oil is being squirted onto the towel, all is good. If not, then you may have a clog to sort out, or a lubricator to replace.
Not a large amount of oil needs to be introduced as a lube otherwise it can interfere with operations. A fine mist is enough to keep things moving.
Accessory service. In addition to the hydraulic cylinder being very important to service, pay attention to rod eyes, clevises, brackets and ball joints. Ensure that there is no major play in the cylinder joints from a worn clevis or pivot pin.
Keep oil clean. It’s an obvious point but still has to be made. Most hydraulic failures are caused by contaminated oil. Filter your oil! All those dirt particles like moving up and down inside a cylinder, so ensure that it’s clean as soon as it enters a cylinder for a first time.
Your filters will ideally be high efficiency and make sure they are regularly changed. If you use a pop-up indicator or a differential pressure-gauge then you’ll know when your filter needs to be de-clogged so that it doesn’t send oil down the bypass and enter your hydraulic system unfiltered.
If you have any hydraulic system questions you need answers to, drop us a line and we will see what we can do.
If you’re curious about how hydraulic cylinders work, then you could find this post to be interesting. Let’s take a look at these powerful components that make it possible to move and lift the heaviest of items with ease.
You may not have ever considered this before, but what do you think deploys those huge wheels that aircraft need to land? They are put away tidily throughout a flight, and then when they’re approaching Heathrow, out they pop and all at the pilot’s press of a button.
Landing gear is operated through a hydraulic system. As with any hydraulic system, there are pipes, cylinders and of course hydraulic fluid. The fundamentals of this are the same as with any hydraulic system. When force is applied at one point, it is transmitted to another through the use of incompressible fluid.
Hydraulic cylinders mostly come in parallel pairs that are of differing diameters and are connected by a pipe. The cylinders will be at right angle to the pipe. This arrangement is then filled with a hydraulic fluid such as oil until the cylinders are partly filled.
The space that is left in the hydraulic cylinders will enable the pistons to operate. In one cylinder, the piston will be smaller than in the other. Fluid will be pushed into the chamber of the small piston and when force is applied, it will push the fluid into the chamber of the big piston as it will be incompressible fluid. This will then move the big piston. Due to the difference in size, the effect of the small piston’s movement will be multiplied. So for example if a small piston has a downward force applied to it of 100 lbs – the force on the big piston will be 900 lbs.
Hydraulic cylinders remove the need for a rigid structure when it comes to transferring force between two different points. This can be used to the hydraulic system’s designer’s benefit and a number of twists and turns can be added to the system. For example, there might be a space constraint. Using the different cylinders at different sizes, it’s possible to create a system that will pull, push or even lift heavy weights.
Although the hydraulic systems that are used in our everyday life are not built with cylinders quite as basic as what’s described above, they are fairly similar. Let’s look at the different components involved:
· Cylinder barrel
· Piston rod
· Cylinder bottom (Cap)
· Cylinder head
· Cylinder bottom connection
· Rod glands
There are two different main types of hydraulic cylinders used. The tie rod type of cylinders and the welded body type. The former are used when there is a need for heavy-duty industrial or commercial use. Some are small bore and others large bore. The welded body cylinder type has no steel rods in it. The top of the barrel of the cylinder is welded directly onto the object that is expected and designed to move. Although these cylinders are small in size, they are used in a surprisingly large number of different machines. In some cases it’s necessary to use a telescoping hydraulic cylinder where the piston rod will retract into the barrel of the cylinder.
Hydraulic power has really evolved over the last 50 years or so. Much of the progress has come from the aeronautical industry, surprisingly. Although hydraulics have been used since before the time of the first recorded history, it’s only now that they have really come of age and have made such a tremendous difference to us in so many fields.
Our current blog looks at Hydraulic Cylinders and acts as a guide to help you choose the correct type of cylinder for your hydraulic system.
As system layouts and sizes vary greatly, it can be a bit of a trial and error process to get the correct measurements for fitment. Luckily some manufacturers, such as ourselves, offer a bespoke cylinder option which can be tailored to specific power units with additional options also available, if required.
We will start with the most common type of cylinder, sometimes known as a catalogue cylinder, as they typically come in a range of pre-set measurements so you can browse through the standard sizes to find the best fit for your system. These are especially popular for smaller systems where the operational length of the system isn’t a big concern.
Standard cylinders can be a cheap, cost effective solution, but you have to bear in mind that if you have cut corners to get a non-bespoke cylinder, you may lose some of the extra efficiency and reliability a custom built cylinder could offer.
Next up are the bespoke cylinders themselves; the advantage of these is that they can be factored into the design of a system so form and function are perfectly suited to your custom build.
There are a number of key areas to look at when designing your bespoke cylinder. These include:
Servicing and maintenance plays a big part in ensuring that your cylinder is in prime working condition and with standard cylinders where ports and other components come pre-positioned, being able to service the cylinder easily could become a problem, whereas with bespoke versions the layout of componentry has been optimised to work closely with the system, thus maintenance is more straight forward.
At Hydraproducts we sell both standard and bespoke cylinders and these now form part of our new Components Division, which you can find out more about by clicking here to visit our new Hydraulics components webpage where Cylinders, Valves, Accumulators and more can be found.
To make the best of your hydraulic systems and enjoy the longest service from them, there are some basic rules that should be followed. Read on to discover some of the extensive knowledge that most mechanics get to learn pretty fast when they are working with hydraulic systems:
Cleaning equipment should also be clean. Many mechanics actually use air hoses to clean fittings and components. It’s essential that the air supply is filtered to prevent any foreign objects from contaminating the parts.
Avoid using tape on threads. One mistake that new mechanics may make is to use Teflon tape on thread connections. This can contaminate hydraulic oil and eventually lead to the halting of a system.
We’ve always been a fan of predictive maintenance for hydraulic systems. It can save time, system damage, expense and downtime. If it’s not already embedded into your workshop processes, then we recommend that predictive maintenance is put right in there along with your inspection processes.
In this post we look at the categories that John Moubray uses in his Reliability Centred Maintenance II book to understand how predictive reasoning should be approached. This is then followed by an example of how it could be used to understand what’s happening with your hydraulic system by using your powers of reasoning.
Broken into these 6 major categories, these maintenance actions can save you expense, time and of course loss of productivity through downtime. What any engineer who works with hydraulic systems should focus on are:
1. Dynamic effects including the monitoring of vibration, pulses and acoustic emissions.
2. Particle effects including the monitoring of particles in the operating environments of the component – ie the condition of the lubricant.
3. Chemical effects: monitoring of the chemical elements in the components operating
4. Physical effects such as cracks, wear, fatigue
5. Effect of temperature
6. Effects of electrical
Although Moubray’s list does cover most of the hydraulic systems maintenance needs, it does not cover all and there are new techniques being discovered and devised continually that should be researched. The visual inspection is one of the most basic and necessary of all predictive maintenance techniques.
Putting this to the forefront, it’s important to look for the following during a hydraulic system inspection:
· Both the quantity and the quality of the hydraulic oil in the tank needs to be checked. The appearance should be bright and clear.
· Check for any leaks or weeps around the seals, connectors and component bodies.
· The surface condition of the tubes, pipes and hoses external.
· The cylinder rod-wiper seal condition needs to be checked.
· The cylinder rod surface. Look for scores, nicks and dents.
· The filter clogging indicator position.
· The readings of the operating pressure (test-points and gauges that have been permanently installed should be used)
· The operating temperature of oil (use either an installed thermocouple or a heat gun)
· Listen out for abnormal noises such as knocking and clicking
The success of predictive maintenance tasks depends on whether data is recorded and then how it is analysed, whether it’s collected through human senses or by using sophisticated measuring tools. It is then necessary to take actions that will either remedy the situation or avoid damage from occurring. The process for predictive maintenance is this:
· Data collection
· Analysis of data
· Predictive reasoning to ascertain possible future issues if maintenance is not addressed
As an example, you may prefer to perform an inspection of your system as part of your regular maintenance routine. You may discover that there is a noise that has increased in volume and that there is no longer a smooth cylinder movement with your actuator. There could be an interpretation of this even as there being issues with reliability and performance of the system up ahead including issues with lubricity. These are all issues to record and take note of for future analysis.
In addition it’s necessary to ensure that the interpretation of the data is in the right context. Perhaps your visual inspection reveals an issue with the filter being clogged. You may identify this from the clogging indicator. Although this would not normally be an issue, it is if the last time the filter element was cleaned or changed was just the day before. Although the data is the same, used through the filter of a different context, then your reasoning will be entirely different.
Summary. It’s important to identify issues in hydraulic systems so that action can be taken whilst the issue is still small. Predictive engineering offers this solution. It also makes it possible to refine your system so that you can avoid issues and enable your machine to have less downtime and expense. It’s truly worth getting into the routine of looking for issues early on.
Our engineers are focused on producing mobile hydraulic power packs. We provide insights into hydraulic system maintenance for those who have an interest. If you’re looking for a custom solution to your hydraulic system application needs, contact us today.
The global rise in construction and infrastructure investment, as well as the trend towards increased mechanisation of agricultural processes will benefit the manufacturers and suppliers of hydraulic cylinders over the next decade. These worldwide trends are helping to drive the industry towards a value of $16.44 billion by 2025, according to research conducted by Global Market Insights Inc.
Double acting hydraulic cylinders have dominated the market in recent years, with a global revenue of $7 billion in 2015, mostly due to an increase in demand for mobile equipment. Mobile hydraulic equipment is expected to see a growth of around 4% in the next few years. Welded hydraulic cylinders also featured heavily in the product landscape and this sector is predicted to be worth $11 million by 2025, driven by a rise in heavy plant equipment and the need for customisation for specific applications; a factor that will play a large part in this growth.
Weak economic indicators suggest there may be a slow growth over the next five years in some sectors, as global financial markets adapt to the changing political landscape, but there will be a significant increase in the demand for hydraulic cylinders over the decade as a whole. Governments in developing countries have pledged to invest in infrastructure projects; the Indian government has indicated an investment of $325 million in the infrastructure development by 2020, and in Russia, the move towards mechanising agricultural processes will create significant growth in the demand for hydraulic cylinders for farming and food processing equipment. The sector enjoyed a growth of 3.6% in 2015 alone across Russia and the trend is forecast to continue in that vein.
The increase in demand for materials handling equipment such as; cranes, forklifts and production line machinery will be especially large in the Middle East, with a predicted 5% growth in the market by 2025 driven by that demand. In the USA, the spending in aerospace and defence sectors will drive the growth of the hydraulic cylinder market to an estimated $3 billion by the same date, with increases in manufacturing and construction projects backing up this rise in the demand for hydraulic equipment.
In China a move towards improving infrastructure will see a growth in the hydraulic cylinder market, raising the market share from $0.79 billion in 2015 greatly as the country develops both urban and nationwide transport networks. Maintaining the manufacturing industry in China will also reinforce the demand for hydraulic equipment, as this sector has been the main driving force behind the rapid economic growth the country has enjoyed over the past few years. Investment in infrastructure has been made possible by this significant economic activity.
Germany is also set to play a large part in the rising demand for hydraulic cylinders as it concentrates on renewable energy sources, with a growth of 4% predicted in this sector. It is also expected that more specialist and customised cylinders will be needed for the renewable energy market, leading to better developments in hydraulic cylinder technology that will then help to continue the growth of the sector from 2025 onwards.
As construction and infrastructure spending increases globally every country will be investing more and more in hydraulic cylinders; with specialists set to benefit from the predicted move towards clean energy sources, particularly in Europe, as well as the retro-fitting and replacement of outdated technologies in the agricultural, infrastructure and manufacturing sectors of the Chinese, Indian and Russian economies. Materials handling especially will see a steady growth over the forthcoming decade in most countries, but especially those planning to spend more on construction and production, such as America and the Middle East.
Although using high-pressure hydraulic systems is considered to be one of the safest methods of applying force, there are still some important factors to take into account. They are powerful tools and can take on any bending, lifting, pushing or pulling work that you need performed, but there are some important safety factors that need to be observed.
Surprisingly, one of the weak points of the hydraulic system when it comes to safety is that it is very easy to use. This can lead to complacency and in some cases abuse. As with any type of equipment use, there are rules to be followed and disciplines to observe in order to get the best from these machines whilst keeping yourself and others in the vicinity of the equipment safe from harm. Following these guidelines can also often ensure longer lifespan and greater efficiency of the machinery.
In the following passages we look at the different areas of safety that will need to be taken into consideration when dealing with high pressure hydraulic tools.
Just as with any equipment, it’s necessary to observe standard safety rules. This means that gloves, safety glasses, boots or safety shoes and a hard hat all need to be worn. As in any environment that can be hazardous, these should be considered fundamental necessities.
Although most engineers will take the most obvious precautions to avoid accidents whilst taking the longevity of the equipment life into consideration, most mishaps and issues will come from either not operating the equipment properly or not assembling it in the right way. It’s important to understand each function in addition to being clear how it works. Take time out to learn your machinery and how it works.
Lifting of loads that are over capacity is something that can result in trouble. Not only will the cylinders be at risk of damage but it can also result in bent plungers and blown seals.
Keep in mind the following points:
- Take an estimate of what you think the load will be, then apply a suitable safety factor.
- Keep in mind that some of your pumps will be equipped with relief valves whilst others won’t be.
- The use of a gauge will help to give an indication of which operating loads are safe.
- Your gauge should also be used to determine whether there is any pressure in the system before you make any changes or breaks in the hydraulic connection.
- Check your environment before you either advance or retract a cylinder.
Fundamentally, two types of cylinders are used in hydraulic systems. The single acting and the double acting.
Single acting cylinders may be any of these types:
· Spring return
· Load return
Double acting cylinders work with the use of hydraulics and advance and retract.
It’s important that you follow these safety guideline rules for cylinders:
- If you need to position the cylinder on the ground, ensure that the base is able to bear the weight of it. It wouldn’t be funny to watch your hydraulic cylinder disappear into soil. A jacking based should be used, or at least a steel or timber plate that will enable the load to be spread.
- The saddle should have the load spread across it, and not be point loaded.
- Stay clear of and be careful around any areas that are directly below a load that the hydraulic cylinder is supporting.
- Situate your cylinders in order to give enough clearance space for extension of them.
- Excessive heat is any heat that is above and beyond 65°C. This needs to be avoided otherwise packing will be softened and hoses weakened. If there is heat that is not avoidable, use either a piece of metal or a heat-resistant blanket to protect the cylinder.
- Keep oil connectors clean and wipe any couplers before they are connected. Dust caps are provided for a reason and that’s to keep dust and dirt out. If you choose not to use them, be aware that you’re likely to experience scoring of the cylinder walls and this can lead to the eventual failure of seals.
- Over-extending cylinders should be avoided as not all of them have safety stop-rings installed.
- If you need to add oil to the pump, check whether the cylinder is already extended, if it is be sure not to disconnect them. The trouble with having too much oil in the system is that your reservoir could become pressurised and blow. If it doesn’t blow it will rupture.
Hydraulic Hand pumps
Depending upon the speed and oil capacity of your system, there is likely to be a pump available for each cylinder. These may be power-assisted or they could be manual in nature. Those applications that are lower speed and where it’s necessary to have that added human ‘touch’ will usually have a hand pump. If the application needs faster movement, or the cylinder is particularly large, then it will use a power pump.
It’s essential that the pump valve is suitable for the cylinder. For example, with single acting cylinders, there is usually a pump that has a 2 way or a 3 way valve. This equates to one outlet. When it comes to double acting cylinders you’re likely to find a 4 way valve which means it has 2 outlets. It’s dangerous to use a 2 way valves in combination with a double acting cylinder.
Check the pump reservoir level before using. Fill using the correct procedures if necessary. Remember that pump hoses will shorten when they are filled with pressure, so ensure there is enough slack to handle this.
With regards to power pumps, you can expect to come across one of these types:
· Petrol / Diesel
It’s fairly obvious that hose failure can occur after heavy objects being dropped on the hose cause damage, but it’s surprising how this escapes the thoughts of many engineers. We often hear stories of how something was dropped but then it was a forgotten memory and the next thing the engineer knows, the hose has failed and there has been a hydraulics disaster.
Another strongly recommended tip is that hydraulic equipment should not be carried by the hose. Most of us are well aware of this, but you will need to keep an eye on any young apprentices who are as yet unfamiliar with the norms of operating hydraulic systems. There should also be an eye kept out for any sharp bends in the hose. The internal wire braids can be damaged from this type of event and this will weaken the set up and could result in leaks and at worst a lethal situation.
An essential fundamental when it comes to hydraulic system safety is to check all fittings, hoses and connections to ensure that they are tightened as they should be and that they comply with the amount of pressure that they will need to be able to handle with your specific system.
We generally recommend that hydraulic systems use oil that is suggested by the manufacturer. The system will usually have been manufactured around that oil and the creators know that it will perform best with that particular one. You will need to change the oil periodically. This will ensure that the system does not get damaged by dirty oil. Ensure that hydraulic oils do not touch your skin.
After you have finished using your hydraulic machinery, it’s time to get it ready for the next job. You will need to clean it before storing it. You can do this by wiping it down. You will also need to lubricate any parts that are exposed.
In conclusion, operating hydraulic systems safely entails using the right cylinder with the right pump and the right oil. Although these rules may seem obvious and safe, it’s surprising how many people fail to adhere to them and put themselves and others in danger. Hydraulic equipment is very powerful but it can also be very dangerous.
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