Ag 501.327

      Theory and practice of Rodweeding

     Upper level course.   Instructor permission required.

Prerequisites:  Ag 401 Tillage Basics (Includes prerequisites for Ag 401—Ag 301A, Ag

     Psychology; Ag 303 USDA Regulations;   Ag 372, Horsepower on the Farm;  Ag 398,

     Basic Farm Mechanics)

Credit:  One hour (Includes 15 hour lab—lab fee required)

Lesson 1

     The rodweeder is one of the simplest tillage machines ever invented, rivaling the chisel in lack of complexity.  The machine runs a rod about one inch square beneath the surface of the soil which uproots the weeds, thus the name rodweeder.

     Early ag engineers (make that an inventive old farmer looking for a weed killer more efficient than a harrow and less disruptive to the soil than a plow or disk) found that to keep the rod below the surface of the soil it was necessary to turn the rod opposite to the direction of travel.

      The challenge was how to turn the rod backwards while dragging the machine forwards.  Most rodweeders harness a wheel used to carry the machine to turn the rod backwards.  One method used two gears, one driven by a shaft from a wheel, the other connected to the rod by a shaft.  The second gear is turned backwards by the first gear, a simple transmission.

     Other gear-driven methods used four gears and another shaft to connect the two sets of gears.  The gear machines drive the rod from one end of the rod.

    Most rodweeders use a roller chain to turn the shaft backwards.  This is accomplished by running a sprocket on the underside of the chain loop, which turns the sprocket backwards.

     This machine uses two chains to turn the rod.  One chain connects the double sprocket to a shaft or axle driven by both wheels (ratchets in both wheel hubs allows turning the machine without sliding wheels going at different speeds during the turn).  The other chain connects the double sprocket to a sprocket on the rod. 

      The chain can drive the rod from the middle of the rod by putting a sprocket on the rod.  The tradeoff is the sprocket on the rod goes into the soil deeper than the rod itself, and the sprocket and the drive chain have to be protected from the soil that will wear them out quickly.  Thus the boot with a chisel point on the bottom end.

    

    A problem with the boot is it leaves a bit more of a furrow than one would like to have.  An advantage of the chain drive is no universal joints are required as is the case for gear-driven varieties.  The chain drives probably take less maintenance than the gear drives.

                                  

      The rod is held in place by shanks with changeable points on the end.  A spool on the rod fits into a socket that bolts onto the replaceable point.  Spools and sockets are also replaceable.  The points are reversible.  When one side wears thin, remove the point, turn it over and remount.  The spools and sockets usually outlast the points.

    The rodweeder doesn’t take much horsepower to operate, so standard procedure is to hook two side by side.  The problem is, so that a little green trail doesn’t spring up where the two machines join, it is necessary to overlap the rods by six or eight inches.  This requires pulling one machine slightly in front of the other.

       Many rodweeders use cables to hitch to the tractor.  Cables allow offsetting the two machines.  A yoke keeps the machines from bumping into each other, or from straying too far apart.  The yoke fits loose enough to allow for the offset and for turning corners.

      Best use of the rodweeder is for preparing a seedbed for small grains such as wheat or barley.  While it uproots the unwanted vegetation, the rodweeder creates a firm seedbed suitable for small grains.

     (Note: if you found this lesson perfectly useless, you should bookmark it to be reread during a 3 a. m. attack of insomnia.  If it still proves useless, the class will have to be moved to the education department.)