Fav 700
Fav 900
Hydraulics / Valve fitting
Nitrogen diaphragm accumulator - STSP
E
Testing
Fav 900 chassis number 23/3001 and up
04.12.2001
9620
000002
E
a
1/5
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Nitrogen diaphragm accumulator - STSP
Text-module
If the control pressure (pSt) falls to approx. 16 bar when actuating the SB 23 LS-EHS control
valves, the control valves lock.
Possible cause: leaks in the diaphragm accumulator - STSP
The method for testing the diaphragm accumulator - STSP is described below.
PM-Picturemodule
Text-module
V0
= Rated volume (0.32 litre)
p0
= Initial gas pressure (16 bar)
V1
= Discharged diaphragm accumulator
P1
= Min. working pressure (approx. 17 bar)
V2
= Full diaphragm accumulator
p2
= Max. working pressure (200 bar)
Whereas in pneumatic systems the medium used - air - can be directly compressed to store energy, a
hydraulic fluid is hardly compressible at all.
An inert gas (nitrogen) is used so that it can be stored under pressure nonetheless.
This is compressed by the hydraulic fluid in a pressure vessel and then expands, if necessary, when
hydraulic fluid is discharged.
To ensure that the nitrogen does not mix with the hydraulic fluid (and produce foam), the accumulator is
divided into two chambers by an elastic diaphragm (diaphragm accumulator).
Nitrogen diaphragm accumulator
Volume
Pressure
[litres]
[bar ]
Version A
0.16
16
Version B
0.32
16
When fitting a new diaphragm accumulator:
Fit a version B diaphragm accumulator
Diaphragm accumulator operating principle
PMTAB_Picture