Fluid Conditioning and System Flushing Procedures 7. Bleed the LS (load sensing) pilot line by carefully loosening the pilot line fitting at the pump to allow trapped air to escape. •
On lift trucks equipped with a VDP, the pump will not flow unless there is a demand from the control levers. Fully actuate and hold the last auxiliary lever (third or fourth lever). Allow the system to run unloaded for ten minutes to flush any remaining particles still in the main valve circuit back to the filter. Inspect for leaks and check reservoir level.
8. With the circuits still looped (cylinders not connected), progressively operate each hydraulic function in the following order to flush out any remaining particles and majority of the air in each circuit. First at low speed (low pressure), then at high speed (high flow). •
Auxiliary 3- Set auxiliary speed at ten for highest flow rate on EH valves.
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Auxiliary 4- Set auxiliary speed at ten for highest flow rate on EH valves.
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Tilt
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Lift
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Steering
9. Shut off system, remove circuit loops and connect cylinders. 10. With the cylinders now connected, operate the individual hydraulic functions in the same sequence as above for at least five complete stroke cycles each until all air is expelled and all actuators operate smoothly. Stroke cylinders slowly taking care not to develop high pressure at the end of stroke which can cause dieseling. 11. With system at operating temperature, 50°C (120°F), check and adjust all relief valve settings to specification and set the auxiliary
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1900 SRM 1620 speed setting to match auxiliary requirements. See the Capacities and Specifications Manual for your lift truck model. 12. Functionally test all circuits under load. 13. Check reservoir fluid level, fill to correct level with filtered fluid. 14. Take an oil sample from the designated test port and send off for analysis. 15. Return lift truck to service. 16. After fifty hours of operation, take an oil sample from the designated test port and send off for analysis to verify the system is operating at the target cleanliness level.
Reservoir Fluid Cleaning Times Cleaning times can be affected by various factors. The reasons for this include: •
The filter caddy is cavitating.
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The return wand is not submerged in fluid and is generating air bubbles.
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The filter tower has not been purged.
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Too much fluid turbulence in reservoir.
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The oil is too cold.
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The oil is heavily contaminated with water and particles.
The following table has been developed to provide an estimate of the cleaning times required with the filter caddy. NOTE: See Hydraulic Cleanliness Service Gram for further information on the filter caddies.
