I am learning the drive train hydraulics on my Cat D3G. I understand that the engine powers the hydraulic pump which is just rear of the engine. From there the hydraulic lines power the hydrostatic transmission between the two drive motors that power the tracks. In the course of all of this, I have learned the circuits of lines that do to the two hydraulic filters and the suction (charge) line that feed the pump and return oil to the tank. If I understand this correctly, I have these questions which are the result of gaps in my understanding. The pump looks like it is in fact a dual pump. A front pump and a rear pump that are attached together like simanese (sp?) twins. One of these pumps seems to power the right track motor and the other seems to drive the left track motor. A question I have is this, does this simanese twin pump also power the blade cylinders? Or is there another pump stashed away somewhere that I have not figured out yet? I have a lot of questions that the answer here may raise.
Can't speak for certain on your D3G, but on a Deere there is a pump tandem (2) off the engine to drive two bent-axis motors at the finals. One pump drives each motor individually. The charge pump is a small pump within the main pump that provides back pressure for the hydrostatic circuit and other auxillaries. The hydraulics are driven by a separate hydraulic pump, usually a load sense pump or fixed displacement thats in addition to the hydrostatic pumps. Hope this helps.