Why can hydraulic cylinders relieve pressure? What is the possible reason for not being able to keep

The hydraulic cylinder can relieve pressure, which can only mean that the filling valve of the rodless cavity of the hydraulic cylinder is opened normally. The problem of not being able to hold pressure.

It can be found by the oil circuit diagram.

Packing pressure is to maintain the pressure of the rodless cavity.

The pressure is guaranteed by four aspects: liquid filling valve, pressure holding valve, electromagnetic reversing valve, and cylinder seal.

The aging of the pressure charge valve, the wear and tear of the valve spool may lead to pressure relief. Wear or jamming of the pressure holding valve.

It can also lead to a similar situation. In addition, the solenoid reversing valve is connected to the oil cylinder after the oil circuit passes through the pressure holding valve, so it is unlikely that the pressure will be relieved because of the wear of the electromagnetic reversing valve, and it is excluded.

However, it cannot be ruled out that after the solenoid reversing valve spool is stuck, the pressure holding valve is provided with opening pressure.

As a result, the pressure holding valve is not closed tightly, resulting in pressure relief. In addition, the method of judging whether the hydraulic cylinder is leaking is to use a 5mm thick round iron sheet, put it on the oil port with a rod cavity, seal the oil circuit, if in this case, the hydraulic cylinder is still relieved, and the cylinder itself slowly slides more than once, it means that the sealing ring on the piston of the cylinder is leaking.

Extended information: The structural forms of hydraulic cylinders are various, and there are many ways to classify them: according to the mode of movement, they can be divided into linear reciprocating motion type and rotary swing type; According to the action of hydraulic pressure, it can be divided into single-acting and double-acting type; According to the structural form, it can be divided into piston type, plunger type, multi-stage telescopic sleeve type, rack and pinion type, etc.; According to the installation form, it can be divided into tie rods, earrings, feet, hinges, etc.; According to the pressure level, it can be divided into 16MPa, 25MPa, etc.

In addition to being used individually, hydraulic cylinders can also be combined in two or more or with others.

Agencies are used in combination. to accomplish a special function. The hydraulic cylinder has a simple structure and works reliably in the machine tool.

It is widely used in hydraulic systems.

It is generally believed that the reasons for the peeling of the hard chrome layer on the surface of the cylinder body are as follows.

a.The plating layer is not well bonded. The main reasons for the poor bonding of the electroplating layer are: before electroplating, the degreasing and degreasing treatment of the parts is not sufficient; The activation treatment of the surface of the part is not complete, and the oxide film layer is not removed.

b.The hard liner is worn. The wear of the hard chrome layer is mostly caused by the grinding effect of the friction iron powder of the piston, and the wear is faster when there is moisture in the middle.

Corrosion caused by the difference in contact potential of the metal only occurs where the piston comes into contact with it, and the corrosion occurs in a punctate manner. As mentioned above, when moisture is trapped in the middle, it promotes the development of corrosion. Compared with castings, copper alloys have a higher contact potential difference, so copper alloys have a more severe degree of corrosion.

c.Corrosion due to contact potential differences. Contact potential difference corrosion, which is not easy to occur for long-term operation of hydraulic cylinders; It is a common failure for hydraulic cylinders that have been out of use for a long time.

If the cylinder is to move, there must be a gap, and if there is a gap, there will be leakage. The reason why the pressure cannot be maintained is leakage. Possibly:

1.The seals are broken and aging; 2.It is not possible to maintain pressure by reversing valves, and a check valve should be added to the pipeline.

sealing pressure; 3.It is a common method to use another small pump to supply oil and maintain pressure.

Pressure relief is a very common thing, because the hydraulic system has a gap to move, so it is difficult to avoid oil leakage, but good hydraulic equipment can maintain pressure for a long time, pressure relief is divided into two kinds: one is leakage, one is internal leakage, and the sealing ring can ensure that there is no longer leakage, improve the machining accuracy of the workpiece, ensure the normal operation of the hydraulic cylinder, and reduce the gap between the two as much as possible, but also reduce the internal leakage; At present, machine tool processing can overcome this shortcoming, do not worry; At the same time, it is also necessary to choose the right hydraulic oil, because it has a great influence with temperature, in line with viscosity and temperature characteristics The most important thing is that experience is also important!

Summary. Pressure relief and pressure retention are two concepts, not pressure retention may be in the filling valve (hydraulic press with filling valve), if the system has a pressure holding valve, it may also be this problem, and leakage caused by non-pressure holding. If you suspect that there is a problem with the cylinder, block the cavity that does not enter the oil and then press it up (the slider should be padded when pressing), if the pressure is not maintained, it is not a problem with the cylinder.

Pressure relief and pressure holding are two concepts, not holding pressure may be in the filling valve (hydraulic press with filling valve burning bird), if the system has a front line pressure holding valve, it may also be this problem, and there is leakage caused by non-pressure holding. If you suspect that there is a problem with the cylinder, block the cavity that does not enter the oil and then press it up (when pressing up, the slider should be cushioned), if you don't keep the pressure, it is not a problem with the cylinder.

Hydraulic pumps, distributors, and cylinders are all new cars that are relieved of pressure during normal operation.

The hydraulic oil does not have the problem of rubber bridge width, the oil volume is enough, and the hydraulic lock is also no problem after the jacking is to relieve the pressure If there is no problem with the orange valve, it is the cylinder that is discharged, maybe the piston seal is damaged, and the piston is worn, the seal of the glee ring and nylon ring is broken, or the cylinder barrel is worn out. That is: serious leakage from the oil cylinder.

When the car is parked, it does not leak, that is, it walks on the road for a period of time to relieve pressure.

You can go to the repair shop to find out why.

Failure to maintain pressure is caused by an internal leak in the cylinder.

Hello, it is a pleasure to serve you and give you the following answer: The pressure relief of the hydraulic lock may be caused by the wear or damage of the piston or seal inside the hydraulic lock. The pistons and seals of hydraulic locks can be corroded by hydraulic oil, and the temperature and pressure of hydraulic oil can also affect the performance of hydraulic locks.

In addition, the pistons and seals of hydraulic locks may also be affected by the external environment, such as temperature, humidity, pollutants, etc., which will affect the performance of hydraulic locks. In addition, the pistons and seals of hydraulic locks can also be corroded by hydraulic oil, and the temperature and pressure of the hydraulic oil can also affect the performance of hydraulic locks. In addition, the pistons and seals of hydraulic locks may also be affected by external hail conditions, such as temperature, humidity, contaminants, etc., which will affect the performance of hydraulic locks.

In addition, the pistons and seals of hydraulic locks can also be corroded by hydraulic oil, and the temperature and pressure of the hydraulic oil can also affect the performance of hydraulic locks. In addition, the pistons and seals of hydraulic locks may also be affected by the external environment, such as temperature, humidity, pollutants, etc., which will affect the performance of hydraulic locks. In addition, the pistons and seals of hydraulic locks can also be corroded by the hydraulic pressure, and the temperature and pressure of the hydraulic oil can also affect the performance of the hydraulic lock.

In addition, the pistons and seals of hydraulic locks may also be affected by the external environment, such as temperature, humidity, pollutants, etc., which will affect the performance of hydraulic locks. Therefore, if the piston or seal of the hydraulic lock is worn or damaged, it will cause the hydraulic lock to be depressurized.

Summary. If the hydraulic locking cylinder depressurizes itself, it may be caused by the following reasons:1

Poor cylinder sealing: If the cylinder is poorly sealed, the pressure in the hydraulic system will gradually leak, causing the cylinder to release its own pressure. 2.

Hydraulic system failure: If a component in the hydraulic system fails, such as a pump, valve, or pipe, it can cause the pressure in the hydraulic system to become unstable, causing the cylinder to depressurize itself. 3.

Hydraulic oil quality problems: If the hydraulic oil is not of good quality, such as contamination, excessive moisture or improper viscosity, it can lead to unstable pressure in the hydraulic system, which can cause the cylinder to relieve its own pressure. 4.

Hydraulic locking device failure: If the hydraulic locking device itself fails, such as a failure of the locking device or a poor sealing of the locking device, it can cause the cylinder to relieve pressure on its own.

If the hydraulic locking cylinder is self-depressurized, it may be caused by the following reasons:1Poor cylinder sealing:

If the cylinder is poorly sealed, the pressure in the hydraulic system will gradually leak, causing the cylinder to release its own pressure. 2.Hydraulic system failure:

If a component in the hydraulic system fails, such as a pump, valve, or pipe, it can cause the pressure in the hydraulic system to be unstable, causing the cylinder to vent its own dust-type pressure. 3.Hydraulic oil quality problems:

If the quality of the hydraulic oil is not good, such as contamination, too much moisture or the viscosity is not suitable, it can lead to unstable pressure in the hydraulic system, which can cause the cylinder to relieve itself of pressure. 4.Hydraulic locking device failure:

If the hydraulic locking device itself fails, for example if the locking device fails or the locking device is poorly sealed, it can cause the cylinder to relieve pressure on its own.

If the hydraulic locking cylinder relieves its own pressure, it needs to be inspected and repaired in time to ensure the normal operation of the hydraulic system.