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Pressure and flow control system SYDFE1 series 2X, 3X
| Product description
Bosch Rexroth AG, Edition 10.2021, RE 30011-B
When using the pump combinations
• NG45 with 45/28/18 or
• NG28 with 28/18 or
• NG18 with 18
in conjunction with the SYDZ pre-load valve on the main pump, there is a
mechanical conflict between port “P1” of the pre-load valve and the swivel
angle sensor housing of the built-on rear pump. For this reason, we suggest
that the main pump of the above combinations be equipped with an SAE
flange plate ¾“ (NG28) or 1“ (NG45) having a height of
h = 45 mm. The construction height of the pump assembly therefore changes
by dimension “h“.
Also here, the minimum pressure is ≥ 1 bar. With external pilot oil supply (0479 for
external supply or 0487 for external supply plus regenerative operation for
SYDFE1) pressures ≤ 10 bar are only permitted briefly (max. 10 minutes).
An additionally built-on sandwich plate with shuttle valve automatically switches
the pilot oil supply between the internal or external pilot oil source, with always
the higher pressure level being selected.
A pump for SYDFE1 with external pilot oil supply can be recognized by
• the sandwich plate mounted under the pilot valve and
• the hose routed around the pump case.
With external pilot oil supply, the actuating system of the SYDFE1 pump works
independently of the actual high-pressure circuit, thus allowing an adjustment also
below an operating pressure of 14 bar within the range of “±100 %“ (change in the
direction of displacement!).
In the following situations, the pump swivels to position “-100 %” (motor
operation) in an uncontrolled manner:
• when the enable of the control electronics is missing or
• an error message of the control electronics (exception: J1 set, see
page 63) or
• in the de-energized state of the control electronics
This can lead to cavitation and damage to the pump.
For this reason, special features are to be provided such as a pressure relief and
anti-cavitation valve and actual swivel angle value monitoring.
The pressure relief and anti-cavitation valve diminishes the risk of the pump’s
running dry, the effects of which result in a reduction in the service life of the
pump.
The actual swivel angle value monitor could, for example, switch off the entire
drive or selectively shut off the pilot oil flow.
The following is valid for the actuating pressure:
Pilot oil pressure ≤ minimum operating pr 30 bar
Recommendation:
Absolute pilot oil pressure ≈ 20 bar
Further notes on the operation with external supply:
• With external supply, the pump does not swivel to zero stroke when the control
electronics is de-energized.
• Command values for pressure and flow must always be greater than 1 bar or 5
%, because there is no exact “zero” pressure or “zero” swivel angle due to drift
or inaccurate settings. For this reason, selections equal to zero or only slightly
greater can lead to cavitation in the worst case.
• In order to ensure sufficient lubrication for the pump system at all times, the
actual pressure value must not be less than 10 bar for longer than 10 minutes!
External pilot oil supply
