The simplest and original disc design. The inherent flaw of the single offset disc involves the thrust applied to the lead corner(B) while discing. This imparts a turning moment to the disc (C). The hitch can be adjusted side-to-side to counteract this effect, though changing soil conditions in the field can still cause the disc to swing. It is also thought that the disc gang assembly angle can be adjusted to counter this effect. However, the angle adjustment on these discs is actually used to compensate for disc blade wear.

As the disc blades wear, the effective angle of the entire gang changes - becoming less. Increasing the angle adjustment compensates for this wear. This same thrust at the lead corner is also responsible for the premature blade wear normally experienced at this end of the disc gang assembly. This design is also limited in width. As width increases, so does dimension (A) and eventually the unit becomes so long as to be impractical.

At widths over 20', transport becomes an issue. Some manufactures hinge the extreme ends of the front and rear gang bars to simplify transport. However, these measures seldom survive the stresses of heavy discing and require frequent repair.

To overcome these problems, single offset discs should combine as wide a main frame as possible with maximum weight and rigidity. A wide, heavy frame carrying heavy, rigid gangs will track straighter, last longer and require the least maintenance. KELLO-BILT single offset discs surpass all these requirements.

The KELLO-BILT offset tandem design incorporates width and transportability in one package. The term offset refers to the fact that the front gangs are offset and overlap in the middle to cut out the center balk. Most tandem designs are not offset and rely on either a cultivator shank and shovel or a spring mounted, angled coulter blade to eliminate the center balk.

These systems do not allow for varying working depths and consequently often leave ridges or troughs in the field. The tandem design tracks straighter than an offset because of its symmetrical arrangement. The KELLO-BILT's double wings are designed as wide as possible to spread the structural weight evenly over the width of the disc. It should also be noted that KELLO-BILT hinges the wings to the frame rather than to the gang bars.

Though more expensive to produce, this is an inherently stronger and more durable design. Each section has its own hydraulically controlled transport assembly to allow maximum depth control for a level, smooth finish. Two tapered blades at each rear corner contribute to the smooth finish.

Tapered roller bearings are specifically designed for heavy radial and thrust loads typical of heavy discing operations. This style of bearing is designed so that all elements in the rolling surface and the raceway intersect at a common point on the axis - thus true rolling is obtained.
To learn more about tapered roller bearings, read the excellent article at:

www.timken.com :: Tapered Roller Bearings

Whether trunion mounted or mounted in pressed steel flangettes, radial ball bearings are not suitable for use in heavy tillage discs. As their name indicates they are designed primarily to carry radial loads. As the purpose of discing is to move soil in a direction at a right angle to the disc blade, side thrust is applied to the bearings that carry the disc blades.

Unlike tapered roller bearings, which are designed to accommodate thrust, radial ball bearings deform when thrust is applied. The contact areas between the balls and the raceways are reduced and offset as one raceway attempts to move horizontally relative to the other raceway. This can result in spalling of the metal surfaces and premature bearing failure. In extreme cases, such as rock impact, the raceways may break.

As the bearing is not designed primarily for thrust, neither are the seals which consist of 2 or 3 rubber lips locked to the outer race and riding against the outer surface of the rotating inner race. The deformation of the bearing can cause the seals to invert, be pushed out or lose contact with the inner race. Once contaminants enter the bearing, its failure is assured.