Anthony – The drive shaft turns the variable hydrostatic pump & charge pump. The charge pump continually pumps oil through the entire hydro/hydraulic system whenever the engine is running. The charge pump draws oil from the reservoir and pressurizes it to 90 - 180 psi. This pressurized oil is enough to operate other pumps and the forward & reverse check valves. It also supplies pressure to hydraulic power steering & lift systems.
Hope this helps
Hope this helps