Source: {"pile_set_name": "USPTO Backgrounds"}

In the fabrication of automobiles, trucks, and similar vehicles, it is required that numerous electrical wires pass through the firewall of the vehicle between the operator compartment and the space in which the vehicle motor is housed. Since the passageway for these wires must be sealed to maintain the integrity of the firewall as well as to protect against the elements, it is common practice to pass all wires through the firewall at a limited number of predetermined locations rather than having a multitude of discrete sealed passageways for each individual circuit. Such an arrangement is particularly desirable in electrical systems of large trucks, for example, which may have in excess of 150 separate circuits.
In order to provide desired sealing at the firewall as well as to facilitate initial fabrication of the vehicle, multiple-contact electrical connectors for the wiring harnesses are typically provided at the firewall. The receptacle of the connector normally passes through the firewall in sealing engagement therewith. Wires on opposite sides of the firewall may thereby be quickly and easily interconnected eliminating the need to provide a separate seal for each circuit extending through the firewall.
Of course, it is important that wires on one side of the firewall be electrically coupled with appropriate wires on the opposite side of the firewall for proper operation of the vehicle electrical system; in other words, polarity across the firewall-mounted connector must be maintained. Typically, connectors of this type are provided with polarizing means to preclude misorientation of the plug relative to the receptacle.
One problem with connectors of the type described above is the difficulty in readily adapting them to various designs of vehicles. In this regard, the receptacle and plug of the connector are usually prefabricated to include various lengths of wires selected to meet the design needs of that particular vehicle. In order to incorporate the connector in other vehicles of similar design, it is often desired to utilize smaller wire harnesses and different configurations of plugs. However, heretofore it has always been required to employ a separate receptacle for mating with each type of plug or combinations of plugs and hence, it has not been economically practical to provide custom connectors tailored to meet the needs of a particular application.
In this latter regard, receptacles designed to mate with one size plug, and which would otherwise be compatible with various combinations of smaller plugs, are not suited for use with multiple plugs because the polarizing means of the receptacle is nullified. For example, when two plugs are used to replace a single plug in a connector of given design, only one of the plugs will be controlled by the polarizing means in the original receptacle, the other of the plugs being permitted to mate in a number of different orientations.
A second problem with prior art connectors relates to corrosion and ultimate dielectric breakdown in areas adjacent the mated terminals. This problem is generally the result of inadequately protecting the terminals from the deleterious effects of the elements.
Another problem with the electrical connectors described above concerns coupling and uncoupling the plug and receptacle of the connector. In this regard, the location of the connectors on the vehicle firewall is generally in an area not readily accessible, thereby making manual manipulation of the plugs extremely difficult. Moreover, weathering of the connector over long periods of use often makes it almost impossible to uncouple the plug and receptacle without damaging one or the other. Of course, the force required to couple and uncouple the plug and receptacle increases with the number of contacts in the connector. This factor has heretofore imposed a limit on the number of contacts in connectors of this type. Appurtenant to the coupling problem is that of providing a simple locking means for maintaining mating engagement between the plug and receptacle during the service life of the vehicle.
Yet another problem with installations of the type described relates to removing the receptacle from its securement with the firewall when it is desired to refurbish the vehicle. This problem is particularly acute in heavy duty trucks which may undergo numerous extensive overhauls during their service life. Typically the connector receptacle is mounted in a semi-permanent manner such that removal of the latter for replacement is often difficult and time-consuming.