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tech talk: Bushings Vs. Ball Bearings

Question:

Most bow manufactures are using bushings instead of ball bearings. There is a reason why and how come they do. Anti-friction bearings such as ball bearings and needle or roller bearings do provide less friction than sleeve bearings in most cases. However, their use requires special consideration depending on type of anti-friction bearings selected. If the bearings has an inner race as well as an outer race, special hardened axles are not necessary. If not, the axles must be hardened to the 60 to 63 Rockwell C level to function right. The wheel or cam hub generally must have a larger diameter to accommmodate the bore required to accept the cased bearing. In my mind optimum performance can be achieved with the use of anti-friction bearings , however, I would not say that arrow velocity would have a great gain. I would say that installing anti-friction bearings in an existing cam or eccentric with sleeve bearings would be a formidable match.

Response:

>I would say that installing anti-friction bearings in an > existing cam or eccentric with sleeve bearings would be a formidable > match.

Some might say…impossible even. Have you found an "anti-friction" bearing that has an O.D. and I.D. matching even the finest oil impregnated bronze bushing? Interesting idea though. If your talking about having a static axle and only a bearing on the cam I suppose it would work. (Unless you want your limb tips to have a huge boss for embedding roller bearings) But then again it surely would weight twice as much and cost twice as much….at least. Think about it. The cams don’t constantly spin on the axle, nor does the axle constantly spin withint the limb tips. Roller bearings are best suited for constant velocities.

Response:

> Most bow manufactures are using bushings instead of ball bearings. There > is a reason why and how come they do. ><snip>

That’s nice.  Thanks for that. -Mac

Response:

Back in the old days needle bearings were pretty common. My father had needle bearings in almost all of his bows in the early 1970’s. I never paid attention so I don’t know if he installed them himself or whether they came that way, but I suspect that you could purchase them that way since he didn’t have access to a machine shop. I suspect that the reason they aren’t found in today’s bows is that they really aren’t necessary, and a cam/wheel with bushings is going to be much less expensive than one with bearings. — Arlington, Massachusetts USA

Response:

There was an article in Archery Focus (maybe a year or so back now) on doing a home conversion from bush to bearings. It didn’t sound like a great deal of work, just a pain to locate the components… The author claimed a slight speed increase (IIRC) and an increase in speed stability (less fluctuation). – Hide quoted text — Show quoted text ->I would say that installing anti-friction bearings in an > existing cam or eccentric with sleeve bearings would be a formidable > match. > Some might say…impossible even. > Have you found an "anti-friction" bearing that has an O.D. and I.D. matching > even the finest oil impregnated bronze bushing? > Interesting idea though. If your talking about having a static axle and only > a bearing on the cam I suppose it would work. (Unless you want your limb > tips to have a huge boss for embedding roller bearings) But then again it > surely would weight twice as much and cost twice as much….at least. > Think about it. The cams don’t constantly spin on the axle, nor does the > axle constantly spin withint the limb tips. Roller bearings are best suited > for constant velocities.

Response:

> The author claimed a slight speed increase (IIRC) and an increase in > speed stability (less fluctuation).

Did the author disclose the increased maintenance as well?  I wonder what a rusty needle bearing cage would do for your speed? …if it was me, I’d just stick with quality bushings and aim a bit higher.

Response:

> Most bow manufactures are using bushings instead of ball bearings. There > is a reason why and how come they do.

I see that Alpine Archery has incorporated some type of bearing technology into their Fast Trac series of bows.  Has anyone shot one to know the difference in performance? Chris

Response:

The author claimed he’d been using the modified bow without maintenance for "quite some time now" (nicely unspecific), He also claimed to be having to change his bushings (due to wear) 1-3 times each year… He replaced the bushing with enclosed stainless steel ball bearings, rather than needle bearings, which may have reduced the maintenance overhead. It was the May/June ‘99 issue of AF. – Hide quoted text — Show quoted text -> The author claimed a slight speed increase (IIRC) and an increase in > speed stability (less fluctuation). > Did the author disclose the increased maintenance as well?  I wonder what a > rusty needle bearing cage would do for your speed? > …if it was me, I’d just stick with quality bushings and aim a bit higher. >

Response:

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