How To Repair 3 Stage Cylinder
Repairing hydraulic cylinders may look like a reasonably simple job from the outside looking in but without the right tools and techniques, something equally unproblematic as repairing a hydraulic ram can become a nightmare.
At RYCO 24•7 in Ingleburn we have seen and worked on but about every type of cylinder on the market place, everything from minor 4 in 1 Bucket cylinders to Skip Bin truck cylinders we have seen it all and have learnt a pull a fast one on or two nigh quick and efficient repairs.
We decided to share some of the noesis nosotros gathered over the last decade and answer some of the nearly mutual questions we come across when people attempt to repair hydraulic rams themselves.
Exist sure to read on and acquire how to repair cylinders like the pros do.
What Causes a Hydraulic Cylinder to Leak Downwards?
Also known every bit cylinder featherbed, this is can exist caused past a number of dissimilar factors. Firstly, your hydraulic cylinder piston seals could simply simply be old and over time start to reduce their effectiveness and habiliment to the point where in that location is not enough preload on the hydraulic seals to maintain a 100% positive seal.
Another crusade of cylinder bypass could be internal damage to the seals, piston, barrel or other internal components.
This can be caused by many different factors, the most common ones we come across are, Piston nut loosening to the point of coming away from rod, habiliment strip and bearings could exist worn and causing a metal on metal situation (not platonic in most cases), Dirty hydraulic oil, another hydraulic component failing and metal particles flowing into cylinder and casing damage to cylinder internals, worn/out of circular cylinder barrel.
If the hydraulic cylinder barrel becomes scored, featherbed of the seals will virtually certainly occur, similar if there is damage to the piston.
Sometimes we see hydraulic cylinder bypass acquired by barrel 'bulging' in the centre and therefore creating a larger diameter in the centre of the barrel merely allowing oil to travel effectually the piston and not hold the load required in that department of stroke.
If the cylinder has over centre (too known equally; load holding, crane valves, anti-drib) valves these may not exist adjusted right. Nosotros strongly recommend that if y'all doubtable this that you lot engage a competent person to check and suit them, if not washed correctly impairment to the cylinder, auto parts and/or personal injury could occur.
How Do I Know if My Hydraulic Cylinder is Leaking?
The showtime and near elementary fashion is to clean down the cylinder very well and look for any possible signs that something could be abnormal. External hydraulic oil leaks, dings/impairment to the barrel OD that could be affecting the cylinder butt ID, damage to the rod, bent, scored, broken or cracked weld around clevis/pin eye. These are all telltale signs that further investigation is required.
Whatsoever of the to a higher place unremarkably ways removing the cylinder from the car and stripping downwards for inspection. It is very of import that all the hydraulic cylinder internal components are thoroughly checked and measured as a bore divergence of only 0.2mm can cause grief.
There are also ways of checking to see if a cylinder is bypassing on the machine before deciding to remove the cylinder.
How Do Yous Finish a Hydraulic Cylinder From Leaking?
This depends on a lot of factors, if nosotros keep it straight forward and say that all the parts of the hydraulic cylinder are in serviceable status and so a elementary hydraulic seal replacement should practise the job.
Y'all can source seals from the OEM (Genuine Seal kit) of aftermarket seals can be sourced from various different wholesalers around the world.
In almost cases, you lot will always need to remove the cylinder from service, strip completely, clean and mensurate so yous tin rebuild it. This should stop a hydraulic cylinder from leaking if all the parts are in serviceable condition.
How Do You Remove Air From a Hydraulic Cylinder?
Depending on the design and the type of hydraulic organisation this tin can exist answered in a number of ways. If nosotros choose a standard blazon double-acting cylinder, oil in bottom for extend, oil in the top rod side for retract, these cylinders whether they be in a closed or open loop hydraulic system should be able to self-bleed air as the render flow and air goes back to the hydraulic tank it will breathe to the temper. In some cases, like if the hoses or pipework to the cylinder is extremely long or full stroke of the cylinder is not possible you could end up with air inside the cylinder. Air is non platonic in hydraulic systems and care should always exist taken to minimise this.
In all cases, if y'all doubtable there to be air in the hydraulic system please take some time to acquire how your system operates and how it was designed before jumping in with spanners. Safety is paramount in this type of hydraulic maintenance and bleeding cylinders can be very dangerous to an untrained person.
How Do You lot Safely Remove a Damaged Hydraulic Cylinder?
First things get-go, SAFETY. Take fourth dimension to inspect the machine and written report the surface area in which you need to work. Understand the hydraulic system you lot are working on to a level where you know without question if there is any stored energy present (accumulators, heavy load on cylinders, machine parked on a hill etc), any danger that could hurt yourself or any other person.
Ensure the auto you are working on is tagged out and isolated so others cannot come up and start the machine while y'all are working on it.
Once you have the car locked out and you are certain there is no stored free energy left in the lines you will need to so remove both ends that ready the cylinder to the piece of hydraulic equipment. Handy Hint; Be sure to remove the hoses/pipage piece of work and plug both the cylinder ports and the hoses/pipework first..
Be sure that there is no force per unit area in the cylinder. If the cylinder clevis pins are tight to move information technology could exist due to the fact that the load is still interim on the cylinder. It can also mean your clevis pins are seized and could require engineering assistance to remove.
Removing a cylinder from a hydraulic system can be a messy job, ensure you comprise any hydraulic oil spill that could occur. Plug and cap both the hydraulic hoses and/or pipework along with the ports on the cylinder to ensure no oil is spilt in transit.
Once both the rod end and base cease hydraulic pins take been removed the cylinder can now be removed.
Please note, in between steps may be required depending on size, mounting, location on the machine and application of the cylinder
How to Disassemble a Hydraulic Cylinder?
Take a moment to audit the hydraulic ram and obtain a good understanding of how the cylinder has been assembled.
If we pick a chief boom cylinder to adjust a CAT 301.7D. This cylinder is quite small and tin can be easily removed from the boom assembly past one person.
If this same cylinder is from a Cat 335F the handling and logistics simply from the concrete size of the cylinder need to be considered and can exist a major part of the cylinder repair process
This is where very specialised equipment is required for the stripping and assembling stages. Virtually times these larger type cylinders need to be loaded on a hydraulic strip demote so the rod, gland and piston can be pulled apart with hydraulic force. In these cases, the piston nut will crave slow and controlled hydraulic force to be removed and reinstalled safely.
The first step is ensuring you have the means to exist able to hold the cylinder barrel safely. Glands tin exist retained to the cylinder barrel in a number of different means, the threaded external barrel, threaded internal butt, bolted to the barrel, retaining wire and circlip to proper noun a few.
Occasionally we come beyond glands that are welded and need to be machined off. Near of the welded type glands render the cylinder BER (Beyond Economical Repair)
Depending on the gland type you lot may need a socket set, in hex drive, C-Spanner, Pipe chain wrench or a just simply and pipe wrench. The latter options are non favourable due to the fact that chain wrench'due south and piping wrenches tin can easily damage cylinder components due to their blueprint if delicate care is not taken.
Once the gland has been removed from the butt the rod will need to be secured either in a vice or specialised bench clamp then the piston nut tin can exist removed. Intendance is required so as not to damage the chrome rod surface as damaging this surface tin cause damage and premature failure of seals.
To remove the seals from the piston and the gland a set of seal picks is the best option. They come in a variety of shapes and styles and make light piece of work of stiff, brittle and old hydraulic seals.
Some cylinders are very large to work on a standard type bench and require the mechanical advantage of a hydraulic strip bench.
Modernistic-twenty-four hours hydraulic strip benches contain gland removal, piston nut removal, hydraulic disassembly and associates of the rod into the barrel, hydraulic nut tightening and hydraulic nut loosening, testing and reporting all from the one machine
How Do You Remove A Hydraulic Cylinder Piston Nut?
After yous accept removed the rod assembly from the barrel you will well-nigh definitely need to remove the piston nut or piston (if the piston is threaded and retains itself). Pistons can exist retained past either a nut, threaded piston nut (the piston is threaded and retains itself), roll pin, Clip, circlip or welded direct to rod (not removable)
A uncomplicated socket set or spanner will quickly loosen standard basics along with Pivot punches, ball-peen hammer, circlip pliers. Stubborn or hard to remove piston nuts tin be carefully heated to a measured temperature to release whatever Loctite or rust that is not assisting with the removal procedure.
Careful consideration must be taken we removing glands and piston every bit more often than not in that location may exist a locking safety type design incorporated to assistance the thread from loosening or coming off the rod. These locking designs must be removed prior to whatever type of nut, thread removal technique. They could exist in the form of a scotch key, grub spiral, set up screw with ball, LOCTITE or similar and steel ring tab only to proper noun a few.
The safest way to remove large hydraulic cylinder piston/piston nuts from a rod associates is past the use of a hydraulic disassembly bench that incorporates a hydraulic nut cracker. These are purpose-built and designed for hydraulic repair workshops that professionally rebuild hydraulic cylinders daily.
If it's anything other than a nut that retains the piston onto the rod there may be a need to apply a custom tool or spanner to loosen. At times nosotros need to industry/fabricate tools to exist able to adapt to our strip bench.
How Do You lot Repair Hydraulic Cylinder Scratches?
At times cylinder rods tin can go damaged by external objects as the chrome rod extends out of the barrel on extension and this can leave information technology prone to damage.
Depending on how bad the impairment is, we can repair information technology in three different ways, we can shine if they are not too deep and the chrome is still intact, nosotros can strip off the old chrome and electroplate (re-chrome) the damaged rod or we can manufacture a totally new rod from scratch.
If the barrel of the cylinder is scratched, scored, marked then honing of the barrel should always be considered later on inspection of the surface in the barrel. If the cylinder barrel has any defects, dings, scores, wear marks/shiny spots these areas need to be carefully investigated and honed to clean up.
The most standard and universal type piston seal designs usually permit for a barrel that is 0.305mm over size on bore. If the barrel damage is excessive there are a couple of options, industry, and machine upwardly another butt on a lathe and use as much of existing parts off the old barrel every bit possible or purchase another barrel from an OEM (Original Equipment Manufacturer).
Y'all want to hone the barrel oversize until it cleans up and industry a new oversized piston. This last option might sound anarchistic merely it is extremely fourth dimension and cost-efficient. Most seal designs can be stretched to within a specified limit.
Honing of hydraulic cylinder barrels can be done by either manual hand honing or on a specialised hydraulic cylinder hone motorcar with the appropriate tooling and stones. Specialised hydraulic cylinder hones are large and crave a fair level of operator cognition the become the best performance and surface finish on the cylinder barrel.
How Practice Y'all Repack a Hydraulic Cylinder?
To be able to reseal a cylinder almost of the time information technology will demand to be stripped down and the seals replaced. The main sealing of a hydraulic cylinder rod to the barrel is by either a 5-pack, o band, standard u-loving cup or energized u-cup seal.
In that location are likewise piston seals, wear rings, o rings and backups, glide bushes, buffer seals and other seals depending on the application, size, oil type, oil temperature and working conditions of the cylinder. Hydraulic seals can too exist engineered and manufactured out of various different materials to suit specific applications.
Things to Consider When Reassembling a Hydraulic Cylinder?
- The main point to consider is the safe of yourself and the people around y'all. Hydraulic cylinders can be an free energy source and with modern hydraulic systems incorporating load belongings (over centre) valves and hydraulic accumulators quite unremarkably, actuators (cylinders, motors, final drives) can become an outlet for stored energy nether the right conditions.
- Attempting to remove a load-holding valve on a cylinder that has not been removed correctly tin cause the oil remaining inside the cylinder to pressurize. Removing the valve nether pressure can crusade serious personal injury and/or impairment to cylinder components.
- If you are unsure most any of the higher up, I strongly advise you lot request the service of a skilled and competent person to undertake your repair
How Practice Y'all Make full a Hydraulic Cylinder?
The system design and cylinder type volition determine if you need to bleed and/or pre-fill the hydraulic cylinder or not.
An open-loop hydraulic system generally allows air to return back into the hydraulic reservoir and breath out through the breather cap during a standard test operation. A few operations of complete extension and retraction of the hydraulic cylinder should completely remove the air from the cylinder and lines.
Keep in mind If there is a really long run of hose/tube the air may non make it dorsum to the hydraulic reservoir and may need to be manually exhausted from the system.
With a single-interim type ram (Hoists) similar that found on a truck tipper and dog tipper trailers, these but accept 1 port for the oil to enter and flow back to the hydraulic tank.
Air can get trapped inside and cause staggered functioning or jumpy and jerky raising and lowering. This is due to atmospheric air we breathe existence compressible. (hydraulic oil is non compressible)
These hoists usually have a bleed nipple at the meridian of the cylinder to assist with the air bleeding process.
How Do Y'all Test a Hydraulic Cylinder?
There a few situations where you would desire to test a hydraulic cylinder
One, if the cylinder has just been rebuilt and before installing onto the machine. Testing here could salvage extra labour and downtime if the cylinder is still leaking or causing concern.
This can be done by adapting to a hydraulic system and creating conditions like to or the same as the cylinder was designed for. This is what we call bench testing a cylinder.
If you suspect the cylinder to be bypassing, dropping, leaking downwardly and then you lot tin can examination this past installing gauges on both sides of the cylinder ports and looking for a pressure drop of the working port.
If the cylinder is bypassing internally the oil will be able to bypass around the piston and travel dorsum to the hydraulic tank. This would crusade the system to not be able to accomplish the maximum force per unit area on that excursion. This is chosen on machine testing.
Testing for bypass on a bench tin be done past fully extending the cylinder, turn off the pump and then remove the retract hose. In one case the retract hose has been removed turn on the pump and operate the valve to extend the cylinder. Expect for oil bypassing the piston and coming out of the retract port.
Once you lot accept washed this to tin repeat this on the opposite port to bank check for retraction bypass.
Information technology is also important to audit mid-stroke every bit this is generally where the cylinder will exist doing most of its work. Extend the cylinder to halfway ensuring both sides of the cylinder are full with oil. Remove the extension hose and cap off with a loftier-pressure plug.
Apply hydraulic force per unit area to the retract hose and if the cylinder rod is bypassing the rod will try to extend. This is due to the effective working expanse on the extend side of the piston being larger than the rod side. Equal hydraulic pressure in the organization with the piston seals bypassing will crusade the cylinder rod to extend.
Yous may just have a leak that you are trying to locate and demand to test to find it. Clean the cylinder thoroughly and operate to the maximum organization pressure that the cylinder was designed for. Inspect all areas of the cylinder. Cylinder ports, gland seals, rod seals, all welds on the barrel, along the barrel.
Some leaks can be very pocket-size and can be difficult to locate so exist very diligent in your inspection so equally not to overlook anything.
(Take care non to run any office of your hand or body around any hoses, adaptors or cylinders while you lot are operating or testing every bit hydraulic fluid injection tin can occur if in that location is a leak.
This is caused by oil travelling at high velocity which can pierce through human being peel and enter your bloodstream. This tin can cause serious injury and/or death so please take extra care when testing for leaks on whatever type of hydraulic component.
If you are unsure about whatsoever of the to a higher place recommendations or procedures, I strongly propose you lot asking the service of a skilled and competent person to undertake your repair)
Related questions
Will a Hydraulic Cylinder Piece of work With Air?
In a give-and-take yes you may exist able to get the cylinder to motion only the big advantage that hydraulic oil has over air is the working pressures and likewise the medium used to convey. Compressed air is just that, atmospheric air that has been compressed into a confined space and stored and directed for utilize.
It can exist compressed and therefore only effective up to a certain pressure. Compressed air as well has a high content of water present and this is not good for metal components (corrosion)
Hydraulic oil, on the other manus, is not compressible therefore becomes a expert medium to use for the transfer of free energy. Hydraulic oil likewise acts as lubrication for metal components.
The components used for pneumatic (Air) system and a hydraulic (Oil) system are very different in there structure and design, therefore as a general dominion cannot be interchanged for utilize on either system.
What is the Main Difference Betwixt Pneumatic Cylinders and Hydraulic Cylinders?
The principal difference here is the working pressure level of the two systems. Pneumatics more often than not run in the pressure range of 100-150 psi whereas a hydraulic system tin sew to 10,000psi
Plainly, the construction of pneumatic cylinders and hydraulic cylinders is vastly different. If yous take a close look at a pneumatic cylinder and of its construction, you will notice the textile is usually aluminium.
Aluminium has proficient anti-corrosion properties but its tensile strength is very poor. The aforementioned slice of aluminium in a steel construction would be able to handle a lot higher pressure but would exist susceptible to corrosion from whatever water or atmospheric conditions.
Source: https://www.rycohosesouthwest.com.au/repairing-hydraulic-cylinders-and-rams/
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