Dixon Corporation is a manufacturer of zero-turn riding mowers and tractor mowers for residential and commercial uses. According to the Dixon-ZTR website, the company has been utilizing zero turn technology on its mowers since 1974. Cones are a part of the transmission assembly and help to control torque and steering. Adjusting the cones, specifically, adjusting the distance of the cones from the discups, can create more precise steering control of the mower.
Loosen, but do not remove, the locking nuts on the Allen head pivot bolts at the rear of the transmission using your 11/16-inch open end wrench.
Back off, but do not remove, the outside locking nuts on the torque rods slightly, using your 1/2-inch open end or box end wrench.
Undo the old gap setting between the discup and cones by turning the Allen head pivot bolt and the inside torque rod nut until the discup cradle moves in toward the cone. Turn the torque rod nut twice for every one turn of the pivot bolt, as the threads are much finer. Continue loosening the bolts until the discup just makes contact with the cone but are not jammed up against one another.
Square the discup so it rests perpendicular to the back frame of the transmission. Loosen either the front or back discup, whichever is more inboard holding the Dixon special tool or a pocket square to know when you've reached perpendicular. Adjust until the discup is square and just barely touching end up Release the front or rear that is more inboard than the other and adjust the outboard one in until the discup is square and it is still just barely locked on the cone.
Create a new neutral gap by barely loosening the adjustment bolts so the cups and cones have a .020 to .025 gap between them on both sides of the assembly.
Set the rod lock to neutral by making the space between the bottom rod lock and the lower spring nut a uniform distance of roughly five threads. Rotate the upper spring nut until the gap distance is evenly divided between the upper and lower cones.
Adjust the control rods so the lever stubs are positioned vertically or slightly rearward and the two steering control levers are even. Push the machine forward with the engine off to confirm that there is no sound from the cones abrading the cups. Get rid of any abrading by adjusting the neutral spring nuts. Tighten down all of the nuts to hold the adjustments you just made.
Test the mower by turning it on and driving in a straight line over relatively flat terrain, the mower drives relatively straight when both levers are within 1-inch of touching each other.