LINK AS 2299249 - Caterpillar

Blade Lift Control
Raise Position
When the joystick is moved to the Raise position, the position sensor for the joystick sends a PWM signal to the implement ECM. The implement ECM analyzes the signal from the joystick. The implement ECM then sends a PWM signal that energizes the solenoid valve for raise. The solenoid valve shifts and pilot oil is directed to the pilot chambers of the valve. The oil pressure on the raise end of the lift stem shifts the stem to the Raise position. The the oil pressure on the raise end of the lift stem shifts the stems to the Raise positionHold Position
When blade control lever (22) is in the Hold position, pilot oil is not directed to the main control valve. Pilot oil that is entering the pilot manifold valve (1) is directed back to the hydraulic tank.Lower Position
When the joystick is moved to the Lower position, the position sensor for the joystick sends a PWM signal to the implement ECM. The implement ECM analyzes the signal from the joystick. The implement ECM then sends a PWM signal that energizes the solenoid valve for lower. The solenoid valve shifts and pilot oil is directed to the pilot chambers of the valve. The oil pressure on the lower end of the lift stem shifts the stems to the Lower position. Float Position
When the lift control lever is moved forward to the Float (soft detent) position, the lift lever position sensor sends a PWM signal to the implement ECM. The implement ECM analyzes this signal. The implement ECM then sends a PWM signal that energizes the lower solenoid valve on the implement valve. The hydraulic system will remain in float until the float feature is canceled. The float feature can be canceled by moving the lift control lever out of center. The solenoid valve shifts and pilot oil is directed to the pilot chambers of the valve. The oil pressure on the lower end of the lift stem shifts the stem to the Float position. Lower Position (Dead Engine)
When the blade is off the ground with the engine in the Off position, the blade can be lowered. The pilot accumulator maintains enough pressure for up to 3 minutes to be able to actuate the lift and tilt spools with the engine off. When the lift control lever is moved to the Lower position, the solenoid valve in the pilot control actuators will shift and this movement will allow the oil pressure against the lift stem in the Hold position to shift. Pilot oil is directed to the stem. The stem shifts and this action will allow the trapped oil in the head end of the lift cylinder to return to the hydraulic tank. The solenoid valves will have an adequate amount of pilot pressure to bring the linkage to the ground within 3 minutes of the engine being shut down.
Illustration 5 g03672739
Location of manual lowering valve for blade.
There is also a shuttle valve and a manual lower ball valve