The most critical part of the bladder accumulator, apart from the mechanical part, is the rubber skin. The rubber skin is made by pressure fusing. If its size exceeds a certain range, it is difficult to control in terms of composition, resistance, imperfections and thickness. The biggest problem is that a rupture of the skin bladder stops the accumulator immediately, causing all hydraulic systems to fail.

《Failure 1》Severe pressure drop, often need to replenish the air

The inflatable valve of the skin bag is in the form of a one-way valve, relying on the sealing cone to seal (Figure 1). 

When the accumulator is subjected to vibration during operation, it is possible that the valve spool is loosened, so that the sealing cone surface 1 is not close, resulting in air leakage. In addition, a groove drawn in the cone surface of the spool, or dirt sticking to the cone surface, may also cause air leakage. 

This can be solved by inserting a hard rubber gasket 5 about 3mm thick into the sealing cover 4 of the inflatable valve, and by taking measures such as grinding the sealing cone to make it close.

If the nut 3 on the upper end of the spool comes loose, or if the cartridge tube 2 breaks or leaks, there is a possibility that the nitrogen in the bladder will be drained in an instant.

《Failure 2》The pressure rises slowly when the accumulator is charged, or even can not be raised

（1）The sealing cap 4 of the charging valve is not tightened or loosened when used and leaks nitrogen.

（2）Inflatable valve sealing hard rubber gasket 5 leakage or broken.

（3）Inflated nitrogen bottle air pressure is too low.

（4）Problems with the inflation hydraulic circuit. As shown in Figure 2 with the unloading relief valve 2 composed of liquid filling circuit, when the valve 2 spool jammed in the micro-open, the accumulator 3 charging pressure on the pressure speed is very slow, the larger the valve 2 spool jammed position of the opening, the slower the charging speed. Completely open, then can not make accumulator 3 storage pressure.

（5）There is valve leakage.Identify the causes and take countermeasures.

《Failure 3》Accumulator does not work or it takes a long time to replenish the system.

（1）serious air leakage valve, there is no nitrogen in the bladder, as well as the bladder broken into the oil.

（2）when the maximum working pressure of the system is too low (lower than the pressure of nitrogen in the accumulator resulting in hydraulic oil can not enter the accumulator), the accumulator completely lost the energy storage function (no energy can be stored).

（3）other valves have leaks and other faults. As shown in Figure 3 of the system, when the throttle valve 1 adjustment opening is too large or spool jammed in the fully open position, the accumulator to the system to release the fluid, a large portion of the fluid from the throttle valve to the tank, so the accumulator does not work or to the system to replenish the fluid for a long time. Of course, it will also produce the accumulator charging time long failure. In this case, the opening of the throttle valve 1 can be adjusted downwards to clean the valve.

At present, the skin-type accumulator does not provide a rupture of the early warning indication, only from the observation of the response speed and efficiency of the decline and the precharge pressure drop to make a judgment, to take the necessary measures to prevent the occurrence of serious consequences.