TT-914: Main System Hydraulic Pump Replacement
The Importance of Secondary Component Replacement During Main Pump Replacement
The main system hydraulic pump may require replacement due to environmental issues or normal internal wear over time. When performing this service, the following recommendations are necessary in order to ensure longevity and dependability from the new pump.
Change the oil and filter prior to the initial start-up of the new pump. Foreign material and contaminants in the existing hydraulic oil drastically reduce the life and operation of a new pump. In some instances, immediate damage could result if the suspended particulate matter becomes lodged in an area of the pump critical to its internal lubrication. This could also lead to internal pressure compensating ports or components becoming restricted in movement or function.
In addition, replace the main system relief valve cartridge. This is especially important if the relief valve cartridge was possibly the defective component leading to the pump failure. If left undiagnosed, the new pump would be subjected to full flow across the relief valve. This creates an extreme amount of heat that will lead to overheating of the new pump and subsequent bearing and seal damage leading to repeated pump failure.
Proper pressure setting of both the system and relief pressure is critical. Refer to Technical Procedure TP-610 for additional information on correct pressure setting procedures