Case Pressure; External Shaft Seal Pressure; Temperature; Viscosity - Danfoss H1P 045 Service Manual

Service Manual
H1P 045/053/060/068 Axial Piston Single Pumps
Operating Parameters

Case Pressure

External Shaft Seal Pressure

Temperature

Viscosity

© Danfoss | June 2020
Under normal operating conditions, the rated case pressure must not be exceeded. During cold start case
pressure must be kept below maximum intermittent case pressure. Size drain plumbing accordingly.
The auxiliary pad cavity of axial pumps configured without integral charge pumps is referenced to case
pressure. Units with integral charge pumps have auxiliary mounting pad cavities referenced to charge
inlet (vacuum).
Possible component damage or leakage.
Operation with case pressure in excess of stated limits may damage seals, gaskets, and/or housings,
causing external leakage. Performance may also be affected since charge and system pressure are
additive to case pressure.
In certain applications the input shaft seal may be exposed to external pressure. In order to prevent
damage to the shaft seal the maximum differential pressure from external sources must not exceed 0.4
bar (5.8 psi) over pump case pressure.
The case pressure limits of the pump must also be followed to ensure the shaft seal is not damaged.
C
Caution
Regardless of the differential pressure across the shaft seal, the shaft seal has been known to pump oil
from the external source (e. g. gear box) into the pump case.
The high temperature limits apply at the hottest point in the transmission, which is normally the motor
case drain. The system should generally be run at or below the quoted rated temperature.
The maximum intermittent temperature is based on material properties and should never be
exceeded.
Cold oil will generally not affect the durability of the transmission components, but it may affect the
ability of oil to flow and transmit power; therefore temperatures should remain 16 °C [30 °F] above the
pour point of the hydraulic fluid.
The minimum temperature relates to the physical properties of component materials.
Size heat exchangers to keep the fluid within these limits. Danfoss recommends testing to verify that
these temperature limits are not exceeded.
For maximum efficiency and bearing life, ensure the fluid viscosity remains in the recommended range.
The minimum viscosity should be encountered only during brief occasions of maximum ambient
temperature and severe duty cycle operation.
The maximum viscosity should be encountered only at cold start.
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