 | |
| Illustration 1 | g01168964 |
(1) Head-end Counterbalance Valve (2) Rod-end Counterbalance Valve (3) Load Sense Check (4) Flow Compensator Valve (5) Load Sense Shuttle (6) EH Control Valve | |
The valves for the AccuGrade - Grade Control System are mounted on the end of the existing left-hand and right-hand valve stacks. The valves use the common pump supply and tank drains in the existing valve stacks. Additionally, the valves supply load signal via the existing stack. The cylinder ports of the valves for the AccuGrade - Grade Control System are connected to the blade lift cylinder supply hoses.
Blade Raise
 | |
| Illustration 2 | g01169223 |
Blade Lift (Right) (1) Head-end Counterbalance Valve (2) Rod-end Counterbalance Valve (3) Load Sense Check (4) Flow Compensator Valve (5) Load Sense Shuttle (6) EH Control Valve (7) Bank Valve | |
 | |
| Illustration 3 | g01169284 |
Blade Lift (Left) (1) Head-end Counterbalance Valve (2) Rod-end Counterbalance Valve (3) Load Sense Check (4) Flow Compensator Valve (5) Load Sense Shuttle (6) EH Control Valve (7) Bank Valve | |
When the AccuGrade - Grade Control System commands either the left hand side of the blade or the right hand side of the blade to be raised, the controller provides a signal to the EH Control Valve (4). The EH Control Valve (4) opens to direct pump flow to the rod end counterbalance valve, where the oil passes through the check valve and on to the cylinder rod end port. Oil flow through the EH Control Valve (4) is regulated by the Flow Compensator Valve (5), which maintains a constant pressure drop across the open area within the EH Control Valve (4). The pressure supplied to the inlet of the EH Control Valve (4) is sensed and sent back to the pump controls via the load signal network in the existing valve.
Oil in the cylinder head end returns back to the EH Control Valve (4) where it must overcome the setting of the Head End Counterbalance Valve (7), then proceed through the EH Control Valve (4) to the tank.
Blade Lower
Blade lower with the AccuGrade - Grade Control System is similar to "Blade Raise", except that the EH Control Valve (4) opens a different direction, causing the pump supply to be directed to the cylinder head end port.
Component Descriptions
Load Sense Check - Prevents load signal from manual valve signal network from entering Accugrade valve
Flow Compensator Valve - Maintains 1035 kPa margin across EH Control Valve (4) in order to allow EH Control Valve (4) to consistently regulate flow
EH Control Valve - Directs pump oil to cylinder ports
Load Sense Shuttle - Chooses highest of two cylinder port pressures in order to communicate load pressure back to Flow Compensator Valve (5)
Counterbalance Valves - The Counterbalance Valves (2,7) control the pressure drop on the cylinder to tank side of the control valve. The Counterbalance Valves (2,7) are biased by the opposite cylinder port pressure in order to modulate the pressure that is required for flow to exit the cylinder.