FLUSHING THE HYDRAULIC SYSTEM 2.6 General Information Contamination in the hydraulic system is a major cause of component failure. Contamination can enter the hydraulic system in any of the following ways: 1 When draining the hydraulic system. 2 When disassembling components. 3 Making auxiliary connections with dirty couplers. 4 Normal component wear. 5 Component failure The best way to remove contaminates from the hydrostat- ic drive system is to disassemble each component and flush and clean thoroughly. The hydraulic control circuits may be cleaned by attach- ing a suitable hydraulic filter to the auxiliary couplings and circulating the fluid through it.
2 2-11 Contamination Types There are 2 types of contamination, microscopic, or non visible, and visible. Microscopic contamination is sus- pended in the fluid and moves freely through the hydraulic circuits. Examples of problems caused by microscopic contaminates include the following: 1 Cylinder rod seal leaks. 2 Control valve spools do not return to neutral. 3 Hydraulic system has a high operating temperature. 4 Components wear rapidly. Visible contamination is foreign material that can be found by sight, touch or odor. Some examples of visible contamination include the following: 1 Particles of metal or dirt in the oil. 2 Air in the oil. 3 Odor of burned oil. 4 Water in the oil.