The Ag Shield Ground Following System (GFS) is an agricultural implement designed to enhance the accuracy and efficiency of spraying operations, particularly for Flexicoil PT sprayers. This system aims to improve sprayer accuracy, reduce spray drift, ensure uniform chemical application, and decrease operator stress by maintaining a consistent boom height relative to the ground.
Function Description:
The GFS operates by utilizing gauge wheels on each boom section to sense the ground level. A hydraulic assist system then carries a significant portion of the boom's weight (more than 80%) on hydraulic cylinders, allowing the boom to "float" over uneven terrain. When the GFS master switch is in the "ON" position, the system actively adjusts the boom height to follow the ground contours. In the "OFF" position, the boom functions as a normal manually controlled boom, and it should not be operated with the wheels contacting the ground in this mode.
The system incorporates a control valve and an electronic module to manage hydraulic pressure and boom movements. The in-cab control box provides the operator with visual feedback, including green LEDs that indicate when a boom section is in GFS mode. For open-center hydraulic systems, an optional open-center enable kit allows for specific pressure adjustments to optimize performance.
A key feature introduced in 2006 and later models is an audible buzzer that alerts the operator if a GFS boom section has been disengaged for more than 10 seconds while the master switch is "ON." This helps prevent situations where an operator might lift a boom over an obstacle and forget to re-engage the GFS, potentially leading to reduced life for boom components or GFS gauge wheels due to excessive ground contact.
Another enhancement for open-center systems in later models is an adjustable time delay for the open-center output. This delay, which can be adjusted from 0.5 to 5 seconds, prevents rapid cycling of the open-center bypass valve when the system pressure drops below a preset level, improving the dependability and longevity of the valves and switches, especially in extremely rolling terrain.
Important Technical Specifications:
- Hydraulic Pressure Adjustment: The GFS hydraulic pressure can be adjusted using a 5/32 hex key and a 9/16 wrench. A pressure gauge is integrated into the GFS valve for monitoring.
- Tire Pressure: The recommended maximum tire pressure for the GFS gauge wheels is 10 psi, with 6 psi preferred to maximize the suspension benefits of the tire.
- Electrical System: The electrical connection for the in-cab control box requires a 12V+ DC power source, fused not greater than 15 amps.
- GFS Control Box (2006+): Features a cab buzzer and adjustable time delay for open-center systems.
- Components: The system includes castor wheels (or non-castor wheels for shielded versions), mounts, an in-cab control box, a GFS valve, and an electronic module. Specific part numbers are provided for various components, such as the GFS generic hydraulic module (227710), GFS generic electrical module (227711), and GFS cab control box (227502).
Usage Features:
- Operator Orientation: Directions (left, right, front, rear) are always referenced from the tractor driver's seat, facing the normal direction of travel.
- GFS ON Mode: Used when boom wheels can run on the ground without excessive pulling by crop or stubble, and when only one boom needs to clear an obstacle while the other follows the ground.
- GFS OFF Mode: Used for folding, transport (on road or trailer), service work (cleaning nozzles, greasing), or when spraying crops/stubble that are too high (typically over 8 inches) or pull too hard on the wheel, which could damage the boom.
- Boom Operation Sequence:
- Raise both boom wheels approximately 6 feet (2 m) or to a man's head height.
- Move the GFS master switch to "ON."
- Tap the left boom "DOWN" switch; the boom should float to the ground in 2-3 seconds. If faster or slower, pressure adjustment may be needed. The green "L" light on the switch box should illuminate, indicating GFS mode.
- Repeat for the right boom.
- During operation, boom wheels should frequently skim the ground.
- To clear obstacles, use the "UP" switch to lift the specific boom; the green GFS indicator light for that boom will extinguish.
- After clearing an obstacle, tap (do not hold) the "DOWN" switch to reactivate GFS for that side; the green light should return, and the boom should float to the ground.
- For servicing, move the GFS master switch to "OFF," press the "UP" switch to raise the boom, and follow safety procedures.
- After spraying, move the GFS master switch to "OFF."
- Open Center Operation (Optional): If equipped, the red LED near "OC" on the in-cab control will light when any hydraulic function is used, indicating the open center valve is closing. This helps pull excessive weight off the boom wheel.
- GFS Time Delay Adjustment (2006+ models): For open-center systems, the time delay for the open-center output can be adjusted from 0.5 to 5 seconds. This is done by removing an external screw on the GFS box and gently rotating an internal slot with a 1/16" blade driver.
Maintenance Features:
- Safety Decals: Operators must be familiar with all safety decals, including "OVERHEAD HAZARD" and "HIGH-PRESSURE FLUID HAZARD."
- Hydraulic System Maintenance: All components in the hydraulic system must be kept in good condition and clean. Worn, cut, abraded, flattened, or crimped hoses and steel lines must be replaced. No makeshift repairs are allowed due to the high-pressure nature of the system.
- Leak Detection: When searching for high-pressure hydraulic leaks, wear proper hand and eye protection and use a piece of wood or cardboard as a backstop instead of hands.
- Tire Pressure Check: Regularly check and maintain the GFS gauge wheel tire pressures, preferably at 6 psi.
- Hose and Wire Management: All hoses and wires must be properly snap-tied to prevent chafing.
- Chemical Residue Removal: Wash the machine thoroughly to remove all chemical residue before performing maintenance, wearing appropriate protective gear.
- Troubleshooting: A dedicated troubleshooting section helps diagnose common issues, such as the boom not dropping, green lights not illuminating, or incorrect boom drop speed, providing possible causes and solutions (e.g., checking switches, fuses, voltage, pressure adjustments, or cleaning mud/crop residue).
- Annual Review: Safety instructions and operating procedures should be reviewed annually before the season starts.
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