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Notices On The Valve Use - Bosch Rexroth H-4WEH...XE Series Operating Instructions Manual

4/2 and 4/3 directional valves, internally pilot-operated, externally pilot-operated
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Contact with salt water leads to increased corrosion at the valve. This may
chemically corrode and damage individual components of the valve. So take
suitable corrosion protection measures.

2.7 notices on the valve use

Observe the following information during project planning:
Special application conditions for safe use include that in case of valves with two
solenoids, maximally one solenoid is operated at a time in all operating states.
The simultaneous operation of both solenoids leads to malfunctions, excessive
heating and will result in loss of explosion protection.
Be aware of possible pressure intensification if the valve is connected to the
chamber on the piston rod side of a differential cylinder. If the outflow of the
hydraulic fluid from this chamber is obstructed, pressure on the cylinder may
result in a pressure intensification that may damage cylinder chamber, supply
line, and valve.
To ensure proper functioning, the valve must be bled. It must be ensured that the
values for the minimum pilot pressure specified in "Data sheet 24751-XE, Technical
data, hydraulic" are complied with.
Pressure peaks in the joint return line of more than one valve may cause
unintended movements of the control spool and thus unintended switching
processes. This particularly holds true when valves with detent are used. It is
recommended to use separate return lines.
Ports P, A, B and T as well as the pilot oil ports X and Y are clearly assigned
according to their function and must not be exchanged or closed. The flow is only
admissible in the direction of arrow specified in "Data sheet 24751-XE".
Switching off the valve solenoid results in a voltage peak due to the inductive
effect. The valve solenoid already contains an interference protection circuit
dampening this voltage peak. However, additional external switching measures
have to be taken, if required, in order to avoid connected electric circuits being
influenced by the residual voltage peak. The values for the residual voltage peak
depend on the valve solenoid used, see the "Data sheet 24751-XE".
Safety instructions
RE 24751-XE-B/04.16, H-4WEH...XE..., Bosch Rexroth AG



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