Pozidriv
From Wikipedia, the free encyclopedia
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| Screw drive types | |
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Slotted (flat or straight) |
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Phillips ("crosshead") PH |
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Pozidriv (SupaDriv) PZ |
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Square |
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Robertson (square) |
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Hex |
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Hex socket (Allen) |
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Torx T, TS, TX |
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Tri-Wing |
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Torq-set |
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Spanner head (Snake-eye) |
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Triple square XZN |
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Polydrive |
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One-way - Clutch |
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Spline drive |
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Double hex |
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Bristol |
The Pozidriv (or SupaDriv) is a type of screw head and screwdriver, jointly patented by the Phillips Screw Company and American Screw Company. The name is thought to be an abbreviation of positive drive. It is similar in appearance to the classic Phillips cross-head, but in fact is substantially different. Its greatest advantage over Phillips drives is its decreased likelihood to cam out, which allows great torque to be applied.[1][2][3]
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[edit] Differences
The differences lie in the way that the drivers are machined. The Phillips driver has four simple slots cut out of it, whereas in the case of the Pozidriv, each slot is the result of two machining processes at right angles. The result of this is that the arms of the cross are parallel-sided in the case of Pozidriv, and tapered in the case of Phillips. The pozidriv has four additional points of contact, and does not have the rounded corners that the Phillips screw drive has. In ANSI standards it is referred to as type IA.[4]
The Pozidriv screw can easily be distinguished by lines forged into the screw head at 45 degrees to the slots for the driver. Thus, if the driver slots are at 0, 90, 180 and 270 degrees, the marker lines are at 45, 135, 225 and 315 degrees.
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[edit] Advantages and disadvantages versus Phillips type
This design is intended to decrease the likelihood that the Pozidriv screwdriver will slip out, provide a greater driving surface, and decrease wear and tear.[1] The chief disadvantage of Pozidriv screws is that they are visually quite similar to Phillips, thus many people are unaware of the difference or do not own the correct drivers for them, and use incorrect screwdrivers. This results in difficulty in unscrewing the screw and in damage to the slot, rendering any subsequent use of a correct screwdriver unsatisfactory. Phillips screwdrivers will fit in and turn Pozidriv screws, but will cam out if enough torque is applied, potentially damaging the screw head. The marker lines on a Pozidriv screwdriver will not fit a Phillips screw correctly, and are likely to slip or tear out the screw head.
[edit] References
- ^ a b Pozidriv page at Phillips Screw Company
- ^ http://web.archive.org/web/20080213034011/http://www.wiha.com/index.php/england/informationen_service/service/ratgeber/schraubprofile
- ^ http://www.gexprosupply.com/gexservices/pdf/screws/PhillipsvsPozi.pdf
- ^ "screw drive systems". http://www.sizes.com/tools/screw_drive.htm.
