Near Intersection of I-35 & I-90 Southern Mn. | You asked about Stepper motors.
A Stepper motor is a motor that can be precisely controlled by a computer type device. Stepper motors are used in a variety of situations. Copiers and printers use them alot.
Unlike a common electric motor where the power is On or Off, the stepper motor responds to precise numbers that it receives from the controlling device.
Years ago when I was in Electronics Tech school, one of our assignments was to make a stepper motor perform. Each student was given a different assignment such as "Have the motor turn 90 degrees clockwise, pause 3 seconds, then have the motor turn 240 degrees counterclockwise, pause etc." Our task was to write the code for a Microprocessor to perfrom the task.
For planter drives, the Rawson company uses a Stepper motor. It works something like this. The computer in the tractor calculates how fast the drive should be turning for the population and ground speed that you are planting. The computer sends out "numbers" at the precise rate that will turn the motor at the proper speed for the given conditions.
This Stepper motor does not drive the planter units but sets the pace. Hydraulic power is actually doing the "work" of running the planter. The Hyd drive has some clever linkage to the Stepper motor. This linkage allows more or less oil to flow to the drive in an attempt to keep the drive running at the same speed as the "Pace motor".
Other brands such as Deere use a different concept. With the Deere system there is a PWM hyd valve controlling an orbit motor and an actual separate shaft sensor. The Computer calculates the speed that the shaft should be turning for the given conditons and compares it to the readings it is receiving from the shaft sensor.
If the shaft is turning too slowly, the computer "widens" the pulse width that it sends to the PWM valve. This results in the valve opening slightly more which allows more oil to flow to the motor which should increase the speed. This process is repeated continuously while planting. When the planter should stop planting the computer narrows the pulse so that it effectively is off, the PWM valve shuts and the orbit motor stops.
There are seveal choices for setting up a hyd drive system on a planter. Ag Leader makes a module that will work with the Stepper Style (Rawson) and a different module for the PWM style. In either case the module ties into the Ag Leader Insight or Integra.
You could go with a complete Rawson system where the Rawson control box would be used to run the Rawson drives. The Rawson control box can be connected to another device (FMX, Ag Leader etc.) which would work with the Rawson box to make maps and send over VR prescriptions.
Deere and the other manufactures provide controls to work with their various systems.
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Planter drive: Convert wheel drive to hydraulic drive?
