Event: Drum Mooring Control On (Up Hole Only)

1. See “Drum (Up)” for first sequence of this event.

2. The operator regulates Tension relief Valve (11) on the operator’s console to the desired setting and the pilot pressure signal flows through shuttle Valve (10.2) to Drum Drive Pump (1) control piston is limited to this setting regardless of the command signal from the operator joystick “Up” signal.

3. Pressure flowing through Shuttle Valve (10.2) acts against the pump control piston and drives the pump “Off” stoke, reducing flow output. This actuation in effect makes the drum cable load weightless. If a greater cable load is experienced Drum Drive Motor (4) will rotate to pay out more cable conversely when a lighter load is experience Drum Drive Motor (4) will pay in the cable.

4. A control pressure above the spring setting of the Mooring Control Relief Valve (10.1) will vent to Tank (20) and protect Drum Drive Pump (1) control piston from over pressurization.

5. Shuttle Valve (10.2) also allows a bypass of Drum Drive Pump (1) internal control orifice for fast pump response to the line load.

6. Pressure of the “Up” side of the closed loop can be monitored at Pressure Transducer (29).