oil pumping losses oil is conducted along fluid pathways at a controlled pressure and applied to controlled volumes in a way that provides the necessary force and speed to activate latch pin switching the hydraulic conduits require specific clearances and sizes so that the system has the correct hydraulic stiffness and resulting switching response time the design of the hydraulic system must be coordinated with other elements that comprise the switching mechanism for example the biasing spring 230 in the switching rocker arm 100 oil is transmitted through a series of fluid connected chambers and passages to the latch pin mechanism 201 or any other hydraulically activated latch pin mechanism as described above the hydraulic transmission system begins at oil flow port 506 in the dfhla 110 where oil or another hydraulic fluid at a controlled pressure is introduced pressure can be modulated with a switching device for example a solenoid valve after leaving the ball plunger end 601 oil or other pressurized fluid is directed from this single location through the first oil gallery 144 and the second oil gallery 146 of the inner arm discussed above which have bores sized to minimize pressure drop as oil flows from the ball socket 502 shown in fig1 to the latch pin assembly 201 in fig1 the mechanism 201 for latching inner arm 122 to outer arm 120 which in the illustrated embodiment is found near second end.