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Limit and safety switches: interchangeable components make choices nearly ... unlimited.

As the history books tell, the two primary pillars of the industrial Revolution of the 19th century were the availability of a powerful motive source--James Watt's steam engine--and the introduction of interchangeable parts. The latter innovation, invented by Eli Whitney when he contracted to manufacture musket components, in turn led to mass production, easily replaced parts in a given machine, and the potential for products to be offered as different models using the same core elements. Production-custom became key in everything from cars to coffee makers, even in components from fluid power fittings electronic to power supplies.

The concept of interchangeability has been applied to a line of limit switches from Automation Systems Interconnect Inc, Carlisle, PA. The devices offer all-metal, self-contained interchangeable heads that mount on bodies of either metal (KM series) or plastic (KB series). Such modularity simplifies stock management and assembly of correct types for different production lines. The switch body can contain all the types of auxiliary contacts offered by ASI. Combinations of two or three contacts are possible with snap action or slow break function. Removing the body cover exposes the open-screw-terminal auxiliary contacts for removal as an assembly, to simplify wiring and reduce installation time.

There are nine variations offered, based on the basic switch, that roughly divide into "push plunger" or "lever" actions. These actions can be generated through several types of roller actions or two types of rods that extend out from the switch (one of the rods is ceramic, particularly useful in demanding environments). Another version is a wobble stick design. The operating heads are designed for quick positioning on the body without the need for special tools, and using a unique bayonet fixing mechanism. The heads have axial rotation of 45-degree angles, and the activation arm on rotating lever units can be repositioned at 15-degree angle intervals. The contact blocks also offer a choice of styles, with combinations of two or three contacts possible, with snap action or slow break function.

The KM series housing is constructed from an aluminum-zinc alloy, while the KB housing is a self-extinguishing, double-insulation polymer thermoplastic. The housings are rated at IP65, with an IP20 rating on the contact terminals. Roller material types include rubber, metal and plastic.

The same core switch and selection of contact blocks are offered also in a line of safety switches. Actuation styles include hinge operating, slotted lever or key operated.

The safety and position switches are suited to a broad range of industries and applications; for example, as a simple counting sensor on conveyors or as a switch in repetitive linear motion systems. Other uses include elevator floor switching, machine door safety and enclosure guard switching, and switch duties on food packaging lines and assembly lines.


Circle 155--ASI, or connect directly to their website at
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Title Annotation:Five Star Product Of The Month
Author:Mandel, Richard
Date:May 1, 2004
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