The present invention relates to a power take¬ off adaptor for a conductor rail having a longitudinal switching channel and longitudinal current conductors, whereby the adaptor comprises

- a box-like frame forming a protruding switch¬ ing member that can be inserted into the switching channel, - a group of locking fingers and contact fin¬ gers positioned in the frame,

- a switching means mounted in the frame mov- ably between a switching position, in which the switch¬ ing means moves the fingers to a contact position in which the fingers protrude from the switching member, and a locking position, in which the switching means moves the fingers to a disengaged position in which the fingers are retracted within the switching member, and

- a locking means comprising locking elements positioned in the frame and in the switching means, which locking elements lock the switching means sta¬ tionary in respect of the frame and which are movable in respect of each other by means of the conductor rail to a position unlocking the movement of the switching means when one of the locking elements touches the con¬ ductor rail.

Conductor rail systems of this type are today used quite commonly in various rooms to connect light¬ ing equipment, small machines and the like to a power source by means of a power take-off adaptor. Both vari¬ ous adaptors and various conductor rails have been de¬ veloped and certain adaptor constructions have been presented in Finnish Patent Specifications 47,236 and 84,305, German Offenlegungsschrift 2,810,681 and US Patent Specification 3,960,426.

In order to ensure that the power take-off adaptor has been placed securely in its correct posi¬ tion in the conductor rail before the contact fingers can be moved to make contact with the current conduc- tors of the conductor rail, various locking construc¬ tions have been designed for the adaptors. One locking construction has been disclosed in the above-mentioned Finnish Patent Specification 47,236. It has a latch that is mounted in the switching member of the frame of the adaptor and a retainer part that cooperates with the latch. The latch has a cam which protrudes from the switching member of the adaptor and which is intended to make contact with the bottom of the conductor rail and to push the latch from a locking position to a dis- engaged position when the adaptor has been pushed into place in the longitudinal channel of the conductor rail. In the locking position the latch prevents both the locking fingers of the adaptor from moving to a protruding position so as to make contact with the con- ductor rail and the contact fingers from moving to a protruding position to make contact with the current conductors of the conductor rail. Only when the cam has pushed the latch to the disengaged position can both of these actions be carried out. In this known construction the locking con¬ struction calls for two separate movable locking ele¬ ments and two springs in order to operate in the de¬ sired manner. To provide the same kind of locking ef¬ fect, other kinds of locking constructions have been developed, all of which are comprised of at least one separate movable locking element, such as a lever, bar, catch or the like, and a spring actuating the locking element. The known adaptors therefore have the major drawback that, in the first place, separate components must be manufactured for the locking construction and,

secondly, the components of the locking construction require their own assembly stage. The construction of the adaptor is thus rendered complicated and its assem¬ bly becomes more difficult. The object of the present invention is to pro¬ vide a power take-off adaptor which avoids the above- mentioned drawbacks and is simpler than previous adaptors in terms of its construction and its assembly. This object is achieved by means of a power take-off adaptor according to the invention, which is character¬ ized in that one locking element of the locking means is formed as an integral part of the switching means and the other locking element is formed as an integral part of the frame. The basic idea of the invention is that both locking elements are formed as an integral part of the elements supporting them (the frame or the switching means) and that at least one of the locking elements is formed in such a way that through the action of an ex- ternal force (the conductor rail) the locking element can move from one position (the locking position) to another position (the disengaged position). This allows the locking element to be manufactured in conjunction with manufacture of the element supporting the locking element, thus obviating the need to manufacture dis¬ crete locking components separately. When the adaptor is assembled, a separate stage for assembling the lock¬ ing means is not required, either.

In the following the invention will be de- scribed in greater detail with reference to the accom¬ panying drawings, in which

Figure 1 shows a perspective view of a prefer¬ red embodiment of a power take-off adaptor according to the invention,

Figures 2 and 3 show a side view and an end view of the adaptor with locking means, the adaptor having been inserted into a conductor rail,

Figure 4 shows a perspective view of the switching means of the adaptor,

Figures 5A and 5B show, on a larger scale, a side view of the adaptor' s locking means in a disengag¬ ed position and, similarly, in a locking position and Figures 6 and 7 are schematic cross-sectional views of two additional embodiments of the locking means of the adaptor according to the invention.

The power take-off adaptor shown in Figures 1-3 of the drawings comprises a box-like frame 1 having a switching member 3 that can be inserted into a conduc- tor rail 2 shown in Figure 3, and a first switching shaft 4 that is pivotally mounted with bearings in the frame as well as a second connecting shaft 5 that is mounted with bearings in the frame. The switching shaft is provided with two locking fingers 6 and one contact finger 7, whereas the connecting shaft is provided with two locking fingers 6 and two contact fingers 7. The shafts are connected to each other so as to rotate in sync between a switching position, in which the locking fingers and contact fingers have moved to a position protruding from the switching member, and a locking position, in which the fingers have moved to a disen¬ gaged position retracted within the switching member. The switching shaft is for this purpose provided with a crank 8 which protrudes from the frame and can be moved from a disengaged position shown in Figures 1-4 to a switching position shown with broken lines in Fig¬ ure 2. The contact finger 7 of the connecting shaft can be turned by means of a selector knob 9, which is mounted with bearings to the switching shaft, so that the contact finger extends to the desired side of the

frame at any given time depending on the desired phase connection. The construction and operation of the ad¬ aptor correspond in principle to the adaptor described in Finnish Patent Specification 84,305 and, therefore, the operation of the adaptor will not be described in greater detail in this connection.

The adaptor is also provided with a locking means 10 in order to lock the switching shaft 4 into said disengaged position. The locking means comprises a flexible opening tab 11 in the frame and a flexible retainer tab 12 in the switching shaft. The opening tab is formed in a part la of the frame which, when the adaptor is pushed into the conductor rail, presses against an edge 13a of a longitudinal channel 13 of the conductor rail, as shown in Figure 3.

The opening tab 11 is formed as an integral part of the frame so that the tab extends outside the surface of said part la of the frame when the opening tab is not actuated, i.e., when the adaptor has been disengaged from the conductor rail but is pressed in level with this surface when the adaptor is pushed into the conductor rail and said part la of the frame is pressed against the edge 13a of the longitudinal chan¬ nel. The retainer tab 12 is formed as an integral part of a flange 4a of the switching shaft in such a way that the tab rises into engagement with an abutment 14 in said part la of the frame when the retainer tab is not actuated, i.e., when the switching shaft has been moved to the disengaged position by means of the cam 8 in order to connect the adaptor to the conductor rail or to disengage it from the rail. The opening tab and the retainer tab are arranged to lie one above the other in this disengaged position in such a way that

the retainer tab is able to snap in place behind the abutment 14 and to seat under the opening tab.

When the adaptor is inserted into the conductor rail and the edge 13a of its longitudinal channel is positioned against the part la of the frame of the adaptor, the opening tab 11 is pressed in level with this part and at the same time presses the retainer tab 12 towards the cam so that the retainer tab is released from engagement with the abutment 14 of the frame, Fig- ure 5B. The switching shaft is thus released from its locked state and can be moved, by turning the crank, to the switching position in which the adaptor is seated firmly in the conductor rail and the contact fingers come into contact with its current conductors 15. When the adaptor is to be removed from the con¬ ductor rail, the switching shaft is turned by the crank back to the locking position such that the adaptor is disengaged from engagement with the conductor rail and can be pulled out of the channel of the conductor rail. In this case, the opening tab 11 is able to flex back to its original position and the retainer tab 12, thanks to its flexibility, snaps into engagement with the abutment 14 of the frame such that the switching shaft becomes unpivotally locked to the frame, Figure 5A.

It is to be noted that no separate parts need be manufactured for the locking means 10, the necessary locking elements being formed during the manufacture of the frame and the switching means. Nor is any special assembly stage required for the locking means, since instead the locking elements assume their correct posi¬ tions during the assembly of the frame and the switch¬ ing means.

In the embodiment of the adaptor shown in Fig- ure 6, locking means 20 comprises a flexible locking

tab 21, which is formed integrally with the frame and has a retainer cam 22 which engages with a groove 23 in the flange 4a of the switching shaft 4. When the adaptor is inserted into the longitudinal channel of the conductor rail, the channel edge 13a presses the locking tab downwards, whereby the switching shaft is released and can be turned.

In the embodiment of the adaptor shown in Fig¬ ure 7, locking means 30 comprises a flexible retainer tab 31 which is formed in the flange of the switching shaft 4. The retainer tab engages behind the abutment 14 in the part la of the frame and extends above the upper surface of said part. When the adaptor is insert¬ ed into the longitudinal channel of the conductor rail, the channel edge 13a presses the retainer tab down¬ wards, whereby its bevelled upper edge 31a allows the tab to move under the part la of the frame when the switching shaft 4 is turned by means of the crank 8.

The Figures and the description relating thereto are intended only to illustrate the idea of the invention. In its details, the adaptor according to the invention can vary within the scope of the claims. The invention can also be applied to adaptors in which the construction for displacing the locking fingers and contact fingers is different from what has been de¬ scribed above and shown in the drawings.