Variable-Rate Drive (VRD) Overview

The Variable-Rate Drive system uses one hydraulic motor for each meter. Various sensors along with data entered into the monitor determines meter speed required to reach a chosen rate.

Additional features of VRD are:

• Ability to program different seed rates to choose from while seeding.
• Ability to change seed rates from the cab without stopping.
• Ability to change seed rates when crossing different soil types.
• Ability to change seed rates when crossing transitions between irrigated and non-irrigated ground.
• Ability to seed different rates with each hydraulic motor or use the same rate for each.
• Compatibility with APEX, and Field Doc™ to design a plan that automatically adjusts product rates in the field.

System Components

• Hydraulic Motor - Motor drives seed meters.
• Valve and Solenoid - Controls oil flow to meter.
• Motor Sensor - Monitors meter motor speed.
• Height Sensor or Switch - Monitors frame height on seeding tool.
• Wheel Speed Sensor - Monitors air cart rear wheel speed.
• System Controller - Processes all signals and data input.
• Monitor Display - Presents data and accepts operator input.

Hydraulic Requirements

Tractor must have either a load sensing hydraulic system or a closed center hydraulic system with flow control. A tractor equipped with power beyond – load sense is recommended, this keeps the tractor from going to high standby, heating oil, and using more fuel.

Each VRD motor requires a nominal hydraulic oil flow of 3.79—30.28 L/min. (1.0—4.0 gpm).

NOTE: Tractors with open center hydraulic systems are not recommended.

System Functionality

• SeedStar™ Controller: A controller mounted on the frame receives power from the tractor and signals from all the system components. The controller processes all the information, controls the hydraulic motor valve, and provides information to the monitor display. The controller communicates over a CAN (Controller Area Network) system. SeedStar™2 is compatible with John Deere GreenStar™ 2 1800 ,2600 and GreenStar™ 3 2630 Displays.
• Monitor Display: A monitor accepts operator inputs and sends data to the controller. The monitor also displays data received from the controller.
• Height Sensor: Implements use an adjustable wheel frame height sensor to start and stop seeding at chosen points as the unit is lowered and raised. The start and stop points are input and adjusted by the operator on the GreenStar™ display.
• Wheel Speed Sensor: A wheel motion sensor mounted on the unit wheel detects motion and indicates the unit is moving.
• Hydraulic Valve and Solenoid: Power to the variable-rate drive motors is supplied by continuous hydraulic flow from the tractor. The controller signals a solenoid operating a hydraulic valve on the motor to control motor speed.
• Motor Sensor: A speed sensor mounted on the motor shaft detects motor speed for feedback to the SeedStar™ controller.
• Monitor Display: The operator enters data into the monitor for product rate, air tool setup information, and meter setup information. The controller uses other operator entered data to adjust motor speed and therefore meter speed.

The following components must be active for system operation:

• Monitor operation—Monitor and controller must have electrical power.
• Product Rates—One or more must be entered and turned ON from the Air Cart—Main screen.
• Continuous hydraulic oil flow—Oil must be flowing to motors.
• Ground Speed from the Air Cart—Controller must detect ground speeds associated with minimum meter speed.
• Height Sensor—Must be calibrated and controller must detect that unit is lowered when sensor is enabled.
• Hydraulic Solenoid—Solenoid on drive motor must have electrical power.

To view status of the VRD, Select Air Cart >> Main softkey >>

In order for variable-rate drive to work, product rates must be entered and turned ON from the Air Cart—Main screen.

A62923-UN-23JUL08

No Activity

A62926-UN-23JUL08

Drives Engaged

• Green—Indicates that meter is on
• Clear—Indicates that meter is off
• Black—Indicates that meter is disengaged by prescription.

System Performance

Low speeds affect performance. Motor performance becomes marginal at low speeds. Performance is dependent on meter speed, which is affected by product rate.

Extreme and sudden changes in speed cause a decrease in product accuracy. To start from a stopped position, use high idle and a low gear. Gradually increase speed to target speed to allow the VRD system time to adjust. Downshift instead of idling down to turn on ends of field.

VRD Component Communication

1. 
   A76757-UN-19NOV12

   VRD Components

   A - System Controller

   B - Hydraulic Motor

   C - Hydraulic Motor Sensor

   D - Wheel Speed Sensor

   E - Tool Height Sensor

   F - Monitor Display

   System controller (A) sends a signal to hydraulic motor (B).

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2. Motor sensor (C), wheel speed sensor (D), and tool height sensor (E) send signals to controller (A).

3. Controller (A) processes sensor signals and displays information on monitor (F).

4. Monitor (F) accepts user input and sends information to controller (A).