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Old 02-23-2014, 10:41 AM   #23
RockHillWill
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Join Date: May 2010
Location: Rock Hill, S.C.
Posts: 985
Default Re: steering box rebuild.

I personally am of the opinion that I would NOT use the needle bearings under any conditions as my concern is that regardless of the bore/fit/hardness concerns or adjustments the roller bearings are not being properly utilized. The rollers in the roller bearing are meant to be in constant rotation and sized by calculating that the roller bearing 'roller' diameter is of such a diameter compared to the shaft diameter that the 'start/stop' points of each diameter no not overlap each other in a specified time frame.(similar to multiple valve springs). The way the roller bearings are used in a steering box the roller in the roller bearing never make one continuous rotation and therefore contacts the same spot on the sector shaft causing a high impact area that repeats itself with EACH steering wheel movement.

This is only my thinking, but it seems to be without question that a properly sized bushing used with a properly hardened shaft is the most efficient way to cope with the short range reversing loads, as no matter the clearance, the load is absorbed over MOST of the length of the bushings and MOST of the diameter of the sector shaft. A simple look at the end view of the contact areas of the two roller/shaft diameters quickly displays the fact that the entire load is placed at the INTERSECTION of two tangential diameters as opposed to the OVERLAPPING contact areas created by two concentric diameters.

The steering input loads are the same regardless of the bearing arrangements, but with the roller to roller condition the unit load numbers are increased GREATLY, and I would think that greatly reduces longevity. Additionally, if only one of the roller bearings should fail, dislodge and hang up between the remaining nearest 'good' rollers, I could easily envision a locking up of the steering box. I have seen this in machine failures.

It is the back and forth movement as opposed to the full rotation of the roller bearing and the high unit loading that gives me the greatest concern.


As always, this is just a thought.
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Last edited by RockHillWill; 02-23-2014 at 10:50 AM.
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