TECHNOLOgy REvIEW


entertainment systems, through to the ultra-rugged demands of construction, mining or agricultural vehicles. Add to this picture planes, boats and trains, and selecting a connector for use in a passenger or freight vehicle quickly becomes a multi-faceted consideration.


A connector’s location has a significant bearing on its specification. An inline wire-to-wire connector used within a vehicle cabin is more likely to be defined by the number of contacts, and the contacts’ current, voltage or other signal-handling characteristics, rather than the need for extreme mechanical ruggedness. That is not to say that such a connector does not need to offer good environmental performance, but quick and easy, low-force mating with positive orientation and locking will be key attributes. The SICMA series from Delphi (formerly FCI MVL) provides 2- to 6-way, mixed loading connectors that also meet the wider temperature range (-40oC to +125oC) and high sealing performance needed for use in engine compartments and other harsh environments.


Molex targets its similar Mizu-P25 series of miniature connectors at motorcycle applications where space is at a premium but also dust and moisture sealing is vital. These connectors feature the smallest mated diameter of any comparable type and were the first in their class to achieve IP67 sealing. They also feature colour-coded housings with polarization for correct mating, easy-to-use positive locks, a low- insertion force terminal design, and are available in two families for low or high voltage operation (up to 125V or 250V respectively).


Wire-to-panel connectors are more likely to focus on mechanical ruggedness and environmental performance. Such connectors may be located on the bulkhead between the engine compartment and cabin of a vehicle, often providing a means of isolating one from the other (referred to by manufacturers as a firewall connector). This is illustrated in figure 2 by Molex’s SRC (sealed rectangular connector) series, targeted at commercial vehicles. Providing up to 84-way, mixed power or signal connections, this range features a sliding, cam-action latch enabling single-handed, blind mating in difficult situations, especially in agricultural machinery, mining and construction equipment, as well as rail and marine applications.


Figure 2: Molex SRC series multi-way wire-to-panel connector


The SRC series provides full IP69K protection against dust and moisture (including water jet) together with a connector retention system that withstands forces greater than 200N, making this product particularly suited to harsh environments with high-vibration levels. Assembly and labour costs are addressed by having the housing, seals, rear cover and terminal block shipped as a pre-assembled unit with a design that ensures crimped terminal leads are correctly located and locked into the connector. The rear cover provides protection and strain relief to the wire-seal interface.


Other manufacturers offer similar wire-to-panel connectors (or wire- to-board as they are sometimes described): Delphi’s CMC series has compact, high-density connectors targeted at electronic engine control unit applications in cars, trucks and buses. The range includes 32, 48 and 64-way cable connectors and 32, 48, 64 and 112-pin headers and supports operation over -40oC to +125oC with waterproof options of IP68 or IP69K. The APD series of circular connectors from ITT Cannon is also aimed at trucks and buses as well as electric and other special vehicle applications. The series provides for high power and high voltage in a high-density design that supports connections up to 51-way. The circular body employs a bayonet coupling method that ensures vibration resistance, giving 100% reliability in harsh environments, and superior IP69K sealing is achieved using individual wire seals.


The connector types reviewed so far provide high performance electrical and environment specifications; featuring multi-way, high-current contacts and operation over a wide temperature range, commonly with full ingress protection from dust and water. However, all have been plastic-bodied designs, which while sufficiently robust for many automotive and similar vehicle applications, are not necessarily heavy duty enough for more industrial environments (including railways) or for use in vulnerable, exposed locations. For these applications, metal- bodied connectors such as Amphenol’s ‘heavy|mate’ brand range may be the answer.


While clearly designed as a heavy-duty connector, Amphenol’s heavy|mate product, shown in figure 3, is also an excellent example of a modular, hybrid connector solution. As such, it serves to illustrate many of the remaining considerations in selecting a connector for transport applications and so we will look at its features and specification in a little more detail.


First and foremost, the heavy|mate connector is designed to be mechanically robust, vibration proof, corrosion resistant and impervious to the ingress of dust and moisture. It is targeted at industrial applications, including the more demanding end of the transportation market but also heavy machinery and the type of robotics equipment found in car assembly plants, giving some appreciation for the kind of use and conditions it needs to endure. The basic connector format is a wire-to-panel design but, unlike those above, it features a metal panel


continues p 14 > 13 focus magazine - issue 15


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