Working Pressure Limits - Bosch REXROTH A4 Series Instruction Manual

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Behavior without enable
or in the case of a fault
or a voltage drop
Maximum working pressure
External pilot oil
Bosch Rexroth AG, A4... with HS5E pilot control valve/Series 3x, RE 92076-01-B/10.2017
• If the hardware enable is canceled, the output stage of the electronics is de-
energized.
With a de-energized proportional valve and a clockwise-turning pump, as well as
control pressure present, the pump swivels in the following cases:
– Standard version A4VSO to swivel angle α = 0% (V
– Standard version A4VSG to swivel angle α = –100%
When the valve electronics are deenergized without control pressure via the spring-
centering:
• The spring-centering of the pump control is standard. It is used for setting and
adjustment in depressurized neutral position, but without defined reset during
high-pressure operation. The spring-centering is not a safety device. To minimize
control fluid consumption, the stroking chambers are sealed in the case of sizes
125 to 1000 and can be bled via ports R2 to R7.

5.3.6 Working pressure limits

Parts that shoot out and escaping jets of fluid!
Risk of serious injuries! The electrical pressure control does not have a pressure
limitation function.
▶ Make sure that the maximum working pressure is not exceeded.
The working pressure that is stated in the data sheet must not be exceeded.
With external pilot oil supply, the HS5E pump runs independently of the actual
high-pressure circuit, which makes possible actual adjustment independently of the
working pressure in the range from 0 to 100% with A4VSO and ±100% with A4VSG
(change of flow direction!)
With a de-energized proportional valve and a clockwise-turning pump, as well
as control pressure present, the pump swivels in the following cases:
– Standard version A4VSO to swivel angle α = 0% (V
– Standard version A4VSG to swivel angle α = -100%.
This can lead to cavitation and damage to the pump.
You can find the maximum and minimum pressures in data sheet 92076.
In the case of energy fluctuations or failures, with adequate control pressure
supply, the unit returns to the basic setting (standard version A4VSO to swivel
angle α = 0% (V ) and standard version A4VSG to swivel angle α =–100%).
g min
Limiting the minimum displacement can cause torque to be generated in the
application.
Check whether additional measures are necessary on your machine for the
application in order to guarantee that the torque is switched off. If necessary,
make sure that these are properly implemented.
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g min
WARnInG
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