Charge Inlet Pressure; Case Pressure; Temperature And Viscosity; Fluid And Filter Recommendations - Danfoss 90 Series Service Manual

Service Manual
Operating parameters

Charge inlet pressure

Case pressure

Temperature and viscosity

Fluid and filter recommendations

Series 90 Pumps
pressure setting is referenced to case pressure. Charge pressure is the differential pressure above case
pressure.
At normal operating temperature charge inlet pressure must not fall below rated charge inlet pressure.
Minimum charge inlet pressure is only allowed at cold start conditions. In some applications it may be
necessary to warm up the fluid by running the engine at limited speed until the system fluid temperature
reaches an acceptable level.
Under normal operating conditions, do not exceed the rated case pressure. During cold start, maintain the
case pressure below maximum intermittent case pressure.
C
Caution
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.
Temperature
The high temperature limits apply at the hottest point in the transmission loop, which is normally the
motor case drain. Maintain system temperature below the quoted rated temperature.
Never exceed the maximum intermittent temperature.
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. Test heat exchangers to verify that these temperature
limits are not exceeded.
Viscosity
For maximum efficiency and bearing life, ensure the fluid viscosity remains in the recommended range.
Minimum viscosity should be encountered only during brief occasions of maximum ambient temperature
and severe duty cycle operation.
Maximum viscosity should be encountered only at cold start.
To ensure optimum pump life, perform regular maintenance of the fluid and filter. Contaminated fluid is
the main cause of unit failure. Maintain fluid cleanliness when servicing.
Check the reservoir daily for proper fluid level, the presence of water, and rancid fluid odor. Fluid
contaminated by water may appear cloudy or milky or free water may settle in the bottom of the
reservoir. Rancid odor indicates the fluid has been exposed to excessive heat. Change the fluid
immediately if these conditions occur. Correct the problem immediately.
Inspect vehicle for leaks daily.
520L0818 • Rev 0101 • August 2015 17