Hello fellow truck go-ers, I haven't seen a lot of info on the 700R4 pump, it's operation and how the pressures (1+2, 3+4 and R) are actually regulated. I though I'd share some info with the community.
Pressure Regulator Valve Operation: The further inward the Pressure Regulator Valve is in the pump, the higher the volume and pressure. Conversely the further out the pressures regulator valve is, the less pressure. When the pressure regulator valve gets enough line pressure against it pushing outward, the valve allows fluid to pass and press against the pump slide tab and reduce pump pressure. Pressure on the pump slide tab causes the slide to push against the slide spring, then move the slide and as a result decrease pump output and pressure. So the more compressed the slide spring the less the pressure. The boost valves effect line pressure and ramp, but total max pressure of pump is set by pressure relief valve. At idle the TV valve is at lowest pull level, meaning low TV pressure, the Pressure Regulator Valve is outward and the pump is producing less line pressure. Modulated TV (TV), 3-4, 1-2 and Rev boost valves effect pressure regulator valve movement inward and result in different line pressure increase for each gear selection.
