most (but not all) of the following will be review. Kaba Peaks uses a uniform pin stack within its product line. A Look at the A2, A3 and A4 Systems Originally, Best Lock Company devised another way to create more bitting com- binations in large master key systems by developing the A3 and A4 systems. For example, a 7-pin core in the standard A2 System will produce approximately 16,000 bittings (not all useful). A 6-pin core will allow for 4,096 changes. The A3 System 279,000 and the A4 System 78,000. The difference in these systems lies in the pin depths (increments). In the standard A2 System, the pin length variation is set at an increment of .0125". However, the smallest wafer at .0125" difference from one bitting to another would allow unintentional op- eration by a key of very similar depth cuts. Therefore, to alleviate this poten- tial problem, every other increment is used in sequential bittings. This is why the A2 System is a two-step progression. For example, a key with the bitting of 592375 might open a core with the bit- ting of 592376. To prevent this, the next bitting in order would have to be 592377. In other words, it takes two steps to cre- ate the next sequential bitting. The A3 System was subsequently de- signed by the Best Lock Company to cre- ate in excess of 17 times more possible combinations. It was created with a larger Bittings Using Total Position Progression System Type: A2 System A3 System (discontinued) A4 System 4,096 46,656 15,625 increment of .0180" so that single step progressions could now be used. This was thought reasonable because the increase of the variation between each increment was just large enough to disallow key in- terchange (or so they thought) and the smallest wafer would move freely without jamming (or so they thought). Eventu- ally, the A3 System was determined to be unreliable, as it allowed key interchange and exhibited core failure. It’s no longer used today for new key systems — only to maintain existing systems. The other major problem with the A3 System was the fact that core failures were occurring based on the smallest wafer (.0180") jamming in the core chambers. So, even though its 279,000 theoretical change keys were advantageous, the A3 System was abandoned. The A4 System was later developed to alleviate the core failure problem and to eliminate key interchange within the system. The pin increment used was .021" and also allowed single-step progressions. Possible key bittings were increased to 78,000 (from only 16,000-plus in the A2 System). Core failure was not a problem in the A4 System. Today, the A2 System is still the most widely used of all three of the A2, A3 and A4 systems. To combinate and orig- inate keys for the A3 and A4 systems, separate key punches (or at least attach- ments/adjustments) must be employed, as well as a separate set of pins. The only interchangeable pins are the A3 top pin Configuration: 6-Pin Core/Cylinder Configuration: 7-Pin Core/Cylinder 16,384 279,936 78,125 #9 (.162") and the A2 top pin #13 (.162"), as well as the bottom pin #0 in all three systems (.110"). The remaining pins are all different. However, the key blanks, springs, caps and capping tools/equip- ment used for A2 System can still be used for A4 keying systems. However, cylinders with .140" spacing will require a .140" capping block/staking tool. Kaba Peaks uses both the A2 System (factory default) and the A4 System, and may use both .140" and .150" spacing. The next installment of this article will cover the pin depth data for the Kaba Peaks A2 and A3 systems. 3-in-1 at a Glance The following chart in Figure 17 illus- trates the number of bittings available within the three keying systems for 6-pin and 7-pin cores/cylinders. For larger Peaks systems, multiplex keyways may be used. These are bittings that are re- peated on other key sections to accom- modate both the need for more bittings when planning a system or for system expansion. Why 2-Step? If you recall, the earlier stated reason is that in a two-step progression, all num- bered bittings 1 through 9 cannot be used, only every other bitting. (Remem- ber?) The reason lies in the small incre- mental differences of the master wafer pins, possibly allowing unintentional key interchange. And, even though a Num- Progression Type: 2-Step 1-Step 1-Step Figure 17. This chart shows the number of bittings available within the three keying systems for 6-pin and 7-pin cores/cylinders. WWW.ALOA.ORG SEPTEMBER 2016 KEYNOTES 47
