The invention relates to a power take-off adapter for a track comprising a longitudinal connection slot and longitudinal current conductors, the power take-off adapter having a box-like frame that comprises: a protruding switching member to be arranged in the connection slot of the conductor track; a first and a second axle member provided with locking and contact fingers for connecting the power take-off adapter arranged in the connection slot of the track mechanically to the track and electrically to the current conductors of the track; a switching means that is switched from a first position to a second position and from the second position to the first position to move the first and second axle member and thereby the locking fingers to a connecting position in which they protrude from the switching member and, respectively, to a retracted disconnecting position.

Track systems of this type are today used commonly in various rooms for connecting lighting equipment, appliances and the like to a power source by means of a power take-off adapter. Various types of both power take¬ off adapters and tracks have been developed. As examples of the prior art are mentioned the solutions of Finnish Patents 84,305 and 92,635.

A drawback of the prior art is, for example, the complexity of the constructions, which raises the production costs. The constructional complexity is, for example, due to the fact that in previously known power take-off adapters, after attaching the power take-off adapter, it has been selected mechanically which phase conductor the power take-off adapter is connected to, i.e. which contact finger moves to a connecting position and which remain in a disconnecting position. Due to the mechanical constructions, the number of components has increased, which has raised the production costs. A further drawback is, for example, that when more lighting equipment is installed in a system or when the positions of the lighting devices are changed, some phase of the track system may be loaded too heavily while the other phases are loaded too lightly.

The object of the invention is to provide a power take-off adapter for a track, eliminating the drawbacks of the prior art. This is achieved with the power take-off adapter provided by the invention. The power take-off adapter of the invention is characterized in that a rotary movement of the switching means is arranged to move all the contact fingers so that they come into contact with the current conductors of the track; and that the power take-off adapter is provided with a separate selecting switch, by which the power take¬ off adapter is electrically connected to the desired phase conductor or electrically disconnected from the phase conductor, so that the power take-off adapter can be attached to the track and detached from the track by a single movement of the switching means, while the phase selected by the selecting switch remains unchanged. The phase conductor to be connected can be selected or changed before the power take-off adapter is attached to the track or after is has been attached to the track. The primary advantage of the invention is that it simplifies the construction of the power take-off adapter and reduces the production costs as compared with the earlier solutions. The number of different components is minimised. Also, no spiral springs or other spring arrangements made of steel wire, which are difficult to handle in the assembly, are needed in the power take-off adapter. A further advantage is that the power take-off adapter can be attached and detached by a single movement of a lever, and the phase selected will not change even though the power take-off adapter is attached to or detached from the track. During the selection of the phase, the power take¬ off adapter can be either attached to or detached from the track. Yet another advantage is that contact pressure is transmitted in the invention from a contact to the selecting switch, whereby the contact pressure of the free phase contacts can be low.

In the following the invention will be described in greater detail by means of a preferred embodiment illustrated in the attached drawing, in which fig. 1 shows a general perspective view of a power take-off adapter of the invention attached to a track,

fig. 2 shows a general perspective view of the power take-off adapter according to the invention, figs. 3 to 7 show views and sectional views of the power take-off adapter according to fig. 2 seen from different directions, and figs. 8 to 10 show perspective sectional views of the power take-off adapter according to fig. 2.

In the figures, a track is indicated generally by reference number 1.

The track 1 can be made, for example, from an aluminium profile. Reference number 2 indicates a longitudinal connection slot of the track. Reference number 3 indicates longitudinal current conductors, i.e. a neutral conductor and phase conductors, of the track.

Reference number 4 in the figures indicates a box-line frame of the power take-off adapter. The box-like frame 4 of the power take-off adapter comprises a protruding switching member 5 to be arranged in the connection slot of the track 1.

The power take-off adapter further comprises a first and a second axle member 6,7. The axle members appear clearly e.g. from fig. 6. The axle members 6,7 are provided with locking fingers 8 and contact fingers 9. The function of the locking fingers 8 is to connect the power take-off adapter mechanically to the track, whereas the function of the contact fingers 9 is to connect the power take-off adapter electrically to the current conductors 3 of the track.

The axle members 6,7 are controlled by a switching means 10. When the switching means 10 is switched from a first position to a second position, both axle members 6,7 rotate about their longitudinal axis, whereby the locking fingers 8 and contact fingers 9 arranged in the axle members 6,7 move from a retracted disconnecting position to a protruding connecting position. Correspondingly, when the switching means 10 is switched from the second position to the first position, the locking fingers 8 and the contact fingers 9 move from the protruding connecting position to the retracted disconnecting position. A simultaneous rotary movement of the axle members

6,7 is effected, for example, by means of suitable gear transmission as shown in the example illustrated in the figures. Such a mechanical power trans¬ mission arrangement is commonly known in connection with power take-off adapters, so it will not be discussed in greater detail herein. With regard to the power transmission arrangement, reference is here made e.g. to Finnish Patent 92,635 mentioned above.

It is an essential idea of the invention that a rotary movement of the switching means 10 is arranged to move all the contact fingers 9 such that they come into contact with the current conductors of the track. The power take-off adapter is also provided with a selecting switch 11 , by which the power take-off adapter can be electrically connected to the desired phase conductor or electrically disconnected from the phase conductor.

The idea of the invention is thus that the power take-off adapter is mechanically connected to the track by a movement of the switching element 10 from a first position to a second position; in other words, the contact fingers come into contact with the neutral and phase conductors 3. The movement of the switching means 10 can be, for example, a movement of about 90°, indicated in figs. 7 and 9 by an arrow. It is clear that when the switching means

10 is switched, the locking means 8 move to a protruding position. The electric connection is provided by a separate selecting switch 11. The selecting switch

11 can be, for example, a sliding clutch that is arranged to control contact strips 12 that effect the electric connection. It should be noted that the phase selected by the selecting switch 11 will not change even though the power take-off adapter is detached from the track 1 or attached to the track 1. This is significant when the load is to be divided evenly between the different phases. The power take-off adapter can be detached from the track simply by switching the switching means 10 from the second position to the first position, whereby both the locking fingers 8 and the contact fingers 9 move to the retracted position. The selecting switch 11 can thus here be held in the previously selected position, so that the phase will not change in connection with later reconnection. The selecting switch 11 can be preferably arranged on

the side of the box-like frame 4 so that it can be operated from both sides of the frame or from one side only. The selecting switch can naturally also be designed so that it can be operated from the side of the frame that is facing downward when the power take-off adapter is attached to the track. The selecting switch can also be designed so that it can be operated from every side of the frame.

The electric connection of the power take-off adapter according to the invention is, in principle, quite conventional, i.e. the contact fingers are connected in the desired manner to the phase and the neutral. Protective grounding is provided by a contact 13 that is arranged to be in contact with a protective ground conductor arranged at the bottom of the connection slot 2 of the track 1.

The above embodiment is in no way intended to restrict the invention, but the invention can be varied quite freely within the scope of the claims. It is thus obvious that the power take-off adapter of the invention or any of its details need not necessarily be exactly as shown in the figures but that other solutions are also possible. The selecting switch, for example, need not necessarily be a sliding clutch as shown in the figures. Another type of switch known per se can also be used as the selecting switch, if it is considered necessary. The selecting switch can also be placed in any part of the frame whatsoever. Further, the shape of the power take-off adapter is not in any way restricted to the shape illustrated in the figures, but the box-like frame can be shaped quite freely according to the need.