The present invention relates generally to hand-held

As is well known to those skilled in the art, cables ties are typically used to bundle or secure a group of elongated articles, such as electrical wires and cables. Cable ties of conventional construction include a cable tie head and an elongated tail extending therefrom. The tail is wrapped around a bundle of articles and thereafter inserted through a passage in the head. The head of the cable tie typically supports a locking element that extends into the head passage and engages the tail to secure the tail to the head, or at least prevent rearward travel of the tail back through the passage so as to disengage the head. In practice, the installer manually places the tie about the articles to be bundled, inserts the tail through the head passage and then manually tightens the tie about the bundle. At this point, a cable tie installation tool may be used to tension the cable tie to a predetermined tension about the bundle. With manually powered tools, one or more grip strokes may be needed to sufficiently tension the tie, depending upon, among other things, how much tension is desired. Once the strap tension approaches the desired level of tension, as predetermined and reflected in the tension setting level of the tool, the tool severs the excess tail portion from the tie, i.e., that portion of the tail which extends beyond the head of the cable tie. With pneumatic tools, a single depression of a button or the like is typically used to activate pneumatic pressure to tension the cable tie to the predetermined tension. Similar to the manually powered tool, once the predetermined tension setting level is reached on a pneumatic tool, the tool severs the excess tail portion from the tie. To address the above-described need, there is provided, described, and claimed herein a cable tie installation tool that is not human-powered and includes in-line power delivery from a source external to the tool. In one embodiment of the invention, there is provided a tool for installing a cable tie, the cable tie having a head portion and an elongate tail portion extending therefrom. The tool includes a housing having a distal end and a proximate end, a tensioning mechanism for tensioning the cable tie to a predetermined tension setting, the tensioning mechanism operatively supported by the housing, a cutting mechanism for severing an excess portion of the tail from the tensioned cable tie, the cutting mechanism operatively supported by the housing, an external power delivery system for actuating the tensioning and cutting mechanisms, the power delivery system for delivering power generally in line with the tensioning mechanism, and a restraint mechanism for providing the predetermined tension setting wherein the restraint mechanism provides the predetermined tension generally in line with the tensioning mechanism. In another embodiment of the invention, there is provided a tool for installing a cable tie, the cable tie having a head portion and an elongate tail portion extending therefrom. The tool includes a housing, a tensioning mechanism for tensioning the cable tie to a predetermined tension setting, the tensioning mechanism operatively supported by the housing, the tensioning mechanism including a linearly reciprocating tension rod and a reverse single acting cylinder, a cutting mechanism for severing an excess portion of the tail from the tensioned cable tie, the cutting mechanism operatively supported by the housing, a restraining mechanism including a ball detent assembly, the restraining mechanism being in communication with the reverse single acting cylinder and being generally axially aligned with the linearly reciprocating tension rod and the reverse single acting cylinder, the restraining mechanism for effecting a predetermined tension setting on the reverse single acting cylinder, and a manually actuable external power delivery system for actuating the tensioning and cutting mechanisms, the power delivery system including a pneumatic power source, a trigger, and a three-way pneumatic valve, whereby when the trigger is manually actuated, pneumatic pressure forces the reverse single acting cylinder to rearwardly pull the linearly reciprocating tension rod, thereby simultaneously restraining movement of the cutting mechanism and tensioning the cable tie until the predetermined tension setting effected by the restraining mechanism is reached in the cable tie, after which the reverse single acting cylinder is released from the pneumatic pressure such that the reverse single acting cylinder is thrust forwardly to activate the cutting mechanism such that it severs the cable tie. Yet another tool is described in U.S. Pat. No. 6,206,053 to Hillegonds. The manually activated and manually powered cable tie tensioning and severing tool described therein provides numerous advantages over prior designs and permits users to quickly and economically apply successive ties under uniform predetermined tensions, resulting in consistent cut-off heights. Additionally, the design includes a tension rod and generally aligned cutting mechanism sleeve, and a concentrically/coaxially mounted restraining means that reduces off-center loads and thereby increases the cycle life of the tool. Despite its advantages over many prior designs, however, the tool still requires manual power to tension the cable ties. Additionally, this prior design utilizes many parts and thus has a somewhat higher manufacturing cost than other designs, particularly those using external power. As the tool embodiments shown and described in U.S. Pat. No. 6,206,053 include some structures and/or assemblies that are similar or identical to specific structures and/or assemblies of the tools described herein, the entire disclosure of the '053 patent is incorporated herein by reference.