Carefully inspect all hydraulic hose and fittings at regular intervals to make certain airworthiness. Investigate any proof of fluid loss or leaks. Check metal tubes for leaks, loose anchorage, scratches, kinks, or other damage. Inspect fittings and connections for leakage, looseness, cracks, burrs, or other damage. Replace or repair defective elements. Ensure the hoses don't chafe against one another and are correctly secured and clamped. hydraulic tensioner pump
a. Replacement of Metal tube. When inspection shows hydraulic hose to be damaged or defective replace the entire line or, if the damaged section is localized, a fix section may be inserted. In replacing aircraft hose, always use tubing of exactly the same size and material as the original line. Use the old tubing as a template when bending the brand new tube, unless it's too greatly damaged, in which case a template may be created from soft iron wire. Soft aluminum tubing (1100, 3003, or 5052) under half-inch outside diameter may be bent by hand. For all the tubing use an acceptable hand or power tube-bending tool. Bend tubing carefully in order to avoid excessive flattening, kinking, or wrinkling. A little bit of flattening in bends is acceptable, but don't exceed 75 percent of the original outside diameter. Excessive flattening will cause fatigue failure of the hydraulic tube. When installing the replacement tubing line it up correctly with the mating part such that it is not forced into alignment by tightening of the coupling nuts.
b. Hose couplings and Tube Connections. Many tube connections are created using flared tube ends with
standard connection fittings: AN-818 (MS 20818) nut and AN-819 (MS 20819) sleeve. In forming flares, slice the tube ends square, file smooth, remove all burrs and sharp edges, and thoroughly clean. The tubing is then flared utilising the correct 37-degree aviation flare forming tool for the size of tubing and type of fitting. A dual flare is applied to soft aluminum tubing 3/8-inch outside diameter and under, and a single flare on all the tubing. In making the connections, use hydraulic fluid as a lubricant and then tighten. Overtightening will damage the tube or fitting, which might create a failure. Under-tightening could cause leakage which may result in a system failure.
CAUTION: Mistaken usage of 45-degree automotive flare forming tools may result in improper tubing flare shape and angle; causing misfit, stress and strain, and probable system failure.
c. Repair of aircraft hydraulic Metal Tube Lines. Minor dents and scratches in tubing may be repaired. Scratches or nicks not deeper than 10 percent of the wall thickness in aluminum alloy tubing, that aren't in the heel of a bend, may be repaired by burnishing with hand tools. Replace lines with severe die marks, seams, or splits in the tube. Any crack or deformity in a flare is unacceptable and cause for rejection. A dent significantly less than 20 percent of the tube diameter is not objectionable unless it's in the heel of a bend. A severely-damaged line should be replaced; however, it might be repaired by cutting out the damaged section and inserting a pipe element of exactly the same size and material. Flare both ends of the undamaged and replacement tube sections and make the connection by using standard unions, sleeves, and tube nuts.If the damaged portion is short enough, omit the insert tube and repair by using one union and two sets of connection hose fittings.
d.Replacement of Flexible Hose. When replacement of flexible hose is essential, use the same type, size, part number, and amount of hose because the line to be replaced. Check TSO requirements. If the replacement of a line with a swaged-end type fitting is essential, obtain new hydraulic hose assemblies of the right size and composition. Certain synthetic oils need a specially compounded synthetic rubber hose, which is compatible. Reference the aircraft manufacturer's service information for the right part number for the replacement hose. If the fittings on each end are of the right type or sleeve type, a replacement may be fabricated. Before cutting new flexible wire braided hose to the correct size, tape the hose tightly with masking tape and cut in the center of the masking tape to avoid fraying. The utilization of a mandrel will prevent cutting the inside of the hose when inserting the fittings. Install hose assemblies without twisting. A hose shouldn't be stretched tight between two fittings as this can lead to overstressing and eventual failure. The length of hose should be sufficient to offer about 5 to 8 percent slack. Avoid tight bends in flex lines as they may result in failure. Never exceed the minimum bend radii.
(1) Teflon hose is found in many aircraft systems because it's superior qualities for many applications. Teflon is compounded from tetrafluoroethylene resin which is unaffected by fluids normally found in aircraft. It comes with an operating range of -65°F to 450 °F. For these reasons, Teflon hose is found in hydraulic and engine lubricating systems where temperatures and pressures preclude the usage of rubber hose. Although Teflon hose has excellent performance qualities, it also has peculiar characteristics that require extra care in handling. It has a tendency to assume a lasting set when confronted with high pressure or temperature. Don't attempt to straighten a line that has been in service. Any excessive bending or twisting could cause kinking or weakening of the tubing wall. Replace any hose that shows signs of leakage, abrasion, or kinking. Any hose suspected of kinking may be checked with a steel ball of proper size.The ball will not move across if the hose is distorted beyond limits.
(2) If the hose fittings are of the reusable type, a replacement hose may be fabricated. When a hose assembly is removed, the ends should be tied, so your preformed shape will be maintained.
(3) All flexible hose installations should be supported at the least every 24 inches. Closer supports are preferred. They should be carefully routed and securely clamped in order to avoid abrasion, kinking, or excessive flexing. Excessive flexing could cause weakening of the hose or loosening at the fittings.
Troubleshooting Hydraulic Machines
Hydraulic machines are found in varied industrial activities today. No doubt manufacturers of hydraulic machinery are taking keen fascination with producing the best machines, which are properly designed, well manufactured and can provide a reliable performance for all years. Any user who uses hydraulic equipments would always like to truly have a trouble free system. mxtd But to truly have a hydraulic machine without giving you any trouble sounds too good to be true. Even though the oil or filter is changed regularly, or even if the preventive maintenance program is followed, the device will probably stop sooner or later of time. This becomes much more dangerous when it happens in the midst of a generation process.
What would you do under this circumstance? It is much better to be ready for such a predicament so your work is not stopped for a long amount of time. This is exactly what is referred as troubleshooting your hydraulic machine. Presenting below some easy approaches to hydraulic troubleshooting.
To begin with, learn hydraulics, find out how they work because this is the best way you are able to handle a problem. Know how all the equipment work, how the system handles pressure, flow and direction, how they're linked to each other. Study the manufacturer's catalog. Gather just as much information about breakdowns, lists of components, pressure settings, testing points, how many actuators, pumps, valves are found in the system.
Don't wait for the time when the device is totally not working. In reality some precautions can be used even when the device is in an operating condition. All hydraulic machines operators must follow a
When actually the hydraulic machine stops working, do the next:
- Discover under what circumstances or what caused the device to stop working?
- Was it at the beginning of the cycle?
- Keep in touch with the device operator.
- Try to obtain just as much information as possible.
- Check the hydraulic schematics. Discover the road from the pump to the actuator. Which actuator or valve was working when the device stopped?
- Discover whether you will find any problems in certain components like pumps, some directional valves, some flow controls, relief valves.
- Perform the flow and pressure test adding an additional element just like the relief valve after the pump, and so on until you get to the cylinder.
When you gather information, its time for you to act. In short, hydraulic problem solving is not a quite simple task, but with proper understanding of hydraulics, with full machine information and equipment, troubleshooting becomes easier and faster.
All About Hydraulic Check Valves
Hydraulic check valves are the most trusted valves that allow fluid to flow in one direction in a hydraulic system and prevent reversal of liquid flow. That is why the name the "check valve" ;.Put simply, this device is installed in a tube so your water does not flow backwards in the pipe. There is a mechanism in the pipe which moves according to the flow of the water towards the valve, and when required, the mechanism plugs up the valve opening so that there surely is no flow of water backwards.
In a hydraulic check valve, you will find two openings. The inlet through which the hydraulic fluid enters and a store through which the fluid goes out. A good thing is which they operate automatically. They work in relation with hydraulic pumps, motors and cylinders. The valves control the flow and pressure of the fluid so that there surely is proper functioning of the equipment.
There are different designs for sale in hydraulic valves like ball, plunger, swinging disc, and poppet. With respect to the application area, the size and shape varies. These check valves are found in industrial applications that require hydraulic pumps, like in automotive braking systems, vehicles, construction tools, including city water and sewer systems. They are found in systems the place where a backup of fluid could create problems on a large scale.
Hydraulic valves are useful for different reasons such as for instance follows:
- The vital role they play is which they prevent flooding if there is extreme back flow of water running through the pipes.
- They stop the damage of the device from water flowing the wrong direction.
- When the device is deterred, the valve helps in preventing the fluid from flowing back the wrong direction. In exchange, they save power and also protect the pipes from water damage.
- They allow liquid flow in one direction.
- They control fluid pressure.
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