US Patent: 477,642
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| Ball-bearing for screw-nuts
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Patentee:
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| Charles E. Brunthaver (exact or similar names) - Washington, DC |
| Manufacturer: |
| Not known to have been produced |
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Patent Dates:
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| Applied: |
Sep. 19, 1891 |
| Granted: |
Jun. 28, 1892 |
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Jeff Joslin
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Description: |
| This is the second-earliest patent we have found for the recirculating-ball mechanism. The inventor's description implies that using ball bearings as the thread-engaging means was a completely new idea, but Crenshaw's patent 155,862, for a screw-press, precedes it by almost 18 years.The primary advantage claimed was greatly reduced friction. No particular application is claimed for the invention and the description gives no hints as to what specific applications might have led to the invention; the other early patents were for screw jacks and presses.The recirculating ball mechanism would prove to be very useful. One popular application would to be for automotive and truck steering: it was readily adapted to power steering, was strong and durable. Recirculating-ball steering was gradually superseded by the rack and pinion mechanism, which is lower cost and provides better "road feel". Recirculating-ball steering is still used on some heavy vehicles; the last major automotive manufacturer to use recirculating-ball steering was Mercedes Benz, who switched away from recirculating ball in the 1990s. British inventor Henry Marles, of Marles Steering Gear Co., is often credited as originating the recirculating-ball steering mechanism; Marles was granted numerous steering-related patents, but we have not found one for a recirculating-ball mechanism.Another notable application of the recirculating-ball mechanism is in ball screws, which are used to convert a rotary position to a linear position. Ball screws have become very common in high-precision machinery that provide X-Y positioning. Ball screws can be made with very little backlash and superior accuracy.We have seen the recirculating-ball idea credited to Stevenson (patent 601,451) and Glenn (patent 610,044); as we have seen, they were, at best, the third and fourth to invent this mechanism. It is possible that Crenshaw, Brunthaver, Stevenson and Glenn each independently developed the same recirculating-ball mechanism. It is remarkable how similar they all are, but making the basic idea work apparently led each of them down the same path to the same design. |
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