The basic principle.
Hydraulic fluid transmits power and also contributes to lubrication, sealing and heat transport. The selected fluid must match the materials and operating requirements of the equipment.
Viscosity is resistance to flow. Oil generally becomes less viscous as temperature rises. Changes in viscosity can affect internal leakage, pressure losses and the response of valves and pumps.
A lift changes behaviour as it warms up.
A temperature-related symptom may point towards viscosity-sensitive leakage or valve behaviour, but it does not identify a failed component by itself.
Follow the relationship.
- TemperatureChanges fluid behaviour.
- CleanlinessAffects precision surfaces and passages.
- Air and waterCan alter response or damage components.
Connect it to the lift.
Particles can wear surfaces or interfere with small clearances. Air and water introduce different problems and need separate consideration. Filtration, reservoir condition and the source of contamination matter alongside fluid age.
A closer look
A fluid sample can provide evidence about contamination and degradation. Its meaning depends on sampling method, service history and the equipment’s requirements; it is not a substitute for assessing the whole circuit.
Check your understanding
Is every hydraulic oil suitable if it has roughly the same appearance?
Reveal the explanation
No. Viscosity grade, additives and compatibility matter, and appearance does not establish condition.