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What is the cause of oil leakage in excavator cylinder? What should we pay attention to in daily operation?
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What is the cause of oil leakage in excavator cylinder? What should we pay attention to in daily operation?

Views: 22     Author: Site Editor     Publish Time: 2019-01-09      Origin: www.fuchun-casting.com

What is the cause of oil leakage in excavator cylinder? What should we pay attention to in daily operation?

Oil cylinder is a very important object in hydraulic system. Once oil leakage occurs in hydraulic cylinder, it will lead to the phenomenon of slow lifting and weak excavation, which seriously affects the efficiency of work. What should we pay attention to when using excavator to avoid oil leakage in hydraulic cylinder?

First, external leakage

1. The seal damage of the piston rod extension end and the piston rod is mostly caused by the piston cylinder being brushed, and also by aging.

2. Seal damage of piston rod extension end and cylinder liner is mostly caused by aging of seal, but also by excessive extrusion of seal when upper cover is used, and also by unreasonable design of many domestic manufacturers of hydraulic cylinders. In most cases, manufacturers are caused by cost savings.

3. The cracking of the joint of the intake and outlet tubing of the cylinder will also lead to the leakage of the hydraulic cylinder.

4. Oil leakage caused by defects on cylinder block or cylinder end cap.

5. Piston rod is pulled and grooved, pitted, etc.

6. Lubricant deterioration causes abnormal increase of cylinder temperature and aging of sealing ring.

7. Oil leakage often occurs when the pressure range of the cylinder is exceeded.

Second, internal leakage

1. The wear ring on the piston is seriously worn, which results in friction between the piston and the cylinder liner, and finally damages the cylinder liner, piston and seal.

2. Seals are invalid for a long time and piston seals (mostly U, V, Y rings, etc.) are aging.

3. Hydraulic oil is dirty, a large number of impurities enter the cylinder and wear the piston seal to a bad state, usually iron scraps or other foreign bodies.

CAT excavator parts

Cautions in the Use of Hydraulic Cylinders

1. In ordinary use, we should pay attention to protecting the outer surface of the piston rod to prevent the damage of the sealing parts caused by bumping and scratching.

It is necessary to clean the sediment on the dustproof ring and bare piston rod of the dynamic seal of the cylinder regularly, so as to prevent the dirt which is not easy to clean from the surface of the piston rod from entering the inner of the cylinder, thus causing damage to the piston, cylinder or seal.

2. In normal use, pay attention to check the connecting parts of threads, bolts and so on frequently, and find loosening and fasten immediately. Because loosening of these places can also cause oil leakage of hydraulic cylinders.

3. Frequently lubricate the joints to prevent rust or abnormal wear in oil-free condition. Especially for some parts with rust phenomenon, it should be treated in time to avoid oil leakage of hydraulic cylinder caused by rust.

4. In normal maintenance, the hydraulic oil should be replaced regularly, and the filter screen of the system should be cleaned in time to ensure the cleanliness of the hydraulic oil, which is also very important for prolonging the service life of the hydraulic cylinder.

5. In normal work, attention should be paid to the control of system temperature, because high oil temperature will reduce the service life of the seals, and long-term high oil temperature will cause permanent deformation of the seals, and seriously will make the seals invalid.

6. Usually when we use it, we have to make a full-scale and full-scale trial run for 3-5 journeys before we work. The purpose of doing this is to exhaust the air in the system and preheat each system, so as to effectively avoid the existence of air or water in the system, which will cause gas explosion in the cylinder block, which will damage the seals and cause leakage and other faults in the cylinder.

hydraulic cylinder parts



  • What is 'multiple certification'?

    This is where a batch of steel meets more than one specification or grade. It is a way of allowing melting shops to produce stainless steel more efficiently by restricting the number of different types of steel. The chemical composition and mechanical properties of the steel can meet more than one grade within the same standard or across a number of standards. This also allows stockholders to minimise stock levels.

    For example, it is common for 1.4401 and 1.4404 (316 and 316L) to be dual certified - that is the carbon content is less than 0.030%. Steel certified to both European and US standards is also common.

  • What surface finishes are available on stainless steels?

    There are many different types of surface finish on stainless steel. Some of these originate from the mill but many are applied later during processing, for example polished, brushed, blasted, etched and coloured finishes.

    The importance of surface finish in determining the corrosion resistance of the stainless steel surface cannot be overemphasised. A rough surface finish can effectively lower the corrosion resistance to that of a lower grade of stainless steel.

  • Can I use stainless steel at high temperatures?

    Various types of stainless steel are used across the whole temperature range from ambient to 1100 deg C. The choice of grade depends on several factors:

    1. Maximum temperature of operation
    2. Time at temperature, cyclic nature of process
    3. Type of atmosphere, oxidising , reducing, sulphidising, carburising.
    4. Strength requirement

    In the European standards, a distinction is made between stainless steels and heat-resisting steels. However, this distinction is often blurred and it is useful to consider them as one range of steels.

    Increasing amounts of Chromium and silicon impart greater oxidation resistance. Increasing amounts of Nickel impart greater carburisation resistance.

  • Can I use stainless steel at low temperatures?

    Austenitic stainless steels are extensively used for service down to as low as liquid helium temperature (-269 deg C). This is largely due to the lack of a clearly defined transition from ductile to brittle fracture in impact toughness testing.

    Toughness is measured by impacting a small sample with a swinging hammer. The distance which the hammer swings after impact is a measure of the toughness. The shorter the distance, the tougher the steel as the energy of the hammer is absorbed by the sample. Toughness is measured in Joules (J). Minimum values of toughness are specified for different applications. A value of 40 J is regarded as reasonable for most service conditions.

    Steels with ferritic or martensitic structures show a sudden change from ductile (safe) to brittle (unsafe) fracture over a small temperature difference. Even the best of these steels show this behaviour at temperatures higher than -100 deg C and in many cases only just below zero.

    In contrast austenitic steels only show a gradual fall in the impact toughness value and are still well above 100 J at -196 deg C.

    Another factor in affecting the choice of steel at low temperature is the ability to resist transformation from austenite to martensite. 

  • Is stainless steel non-magnetic?

    It is commonly stated that “stainless steel is non-magnetic”. This is not strictly true and the real situation is rather more complicated. The degree of magnetic response or magnetic permeability is derived from the microstructure of the steel. A totally non-magnetic material has a relative magnetic permeability of 1. Austenitic structures are totally non-magnetic and so a 100% austenitic stainless steel would have a permeability of 1. In practice this is not achieved. There is always a small amount of ferrite and/or martensite in the steel and so permeability values are always above 1. Typical values for standard austenitic stainless steels can be in the order of 1.05 – 1.1. 

    It is possible for the magnetic permeability of austenitic steels to be changed during processing. For example, cold work and welding are liable to increase the amount of martensite and ferrite respectively in the steel. A familiar example is in a stainless steel sink where the flat drainer has little magnetic response whereas the pressed bowl has a higher response due to the formation of martensite particularly in the corners.

    In practical terms, austenitic stainless steels are used for “non-magnetic” applications, for example magnetic resonance imaging (MRI). In these cases, it is often necessary to agree a maximum magnetic permeability between customer and supplier. It can be as low as 1.004.

    Martensitic, ferritic, duplex and precipitation hardening steels are magnetic.

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