The path of the shuttle is guided across the width of the fabric at least over a substantial portion of the longitudinal path by a guide reed. The shuttle is guided on the guide reed and moved, by magnet coupling to magnetic shuttle moving elements which are carried along the shed, for example by an endless chain, by being coupled together, or the like.
German Pat. No. 30 16 182 describes a multi-system weaving loom built in back-to-back construction. On the front side and the back side, respectively, the shuttles pass through a straight portion of their guide path and through the shed, so that in the straight portion one or more fabric webs can be made. The shuttles are driven by drive elements which are either coupled together or coupled to an endless chain. The drive elements carry permanent magnets on the side facing the shed and the shuttle likewise carries permanent magnets which are in magnetically coupled relation to the drive element magnets. The magnetic coupling provides for moving of the shuttles, as set forth in general principle in U.S. Pat. No. 3,618,640 and German Pat. No. 1,785,147, respectively.
The two essentially straight portions of the guide path for the shuttle are coupled by curved return portions in which the shuttle leaves the shed and is guided over an essentially semi-circular path. Two sprockets are located in the region of the return path over which either the drive chain or the connected drive elements or drive segments are carried, which, upon passing through the return path, are spread out in fan-shape.
An essentially guide reed guides the shuttles in in the straight portion of the shuttle path. The shuttle path is essentially defined by the reed which forms a stable slide surface for the shuttle which is magnetically coupled to the drive segments.
The shuttles are coupled in the region of the semicircular return path by being coupled directly to the drive elements, without interposition of the guide reed or an interposed structure. The facing pole surfaces of the permanent magnets of the shuttle have a foil of plastic of highly slippery surface characteristics applied thereto; between the pole surfaces, thus, of the drive segments and of the shuttle there is only a thin slide foil interposed. This thin slide foil is provided to insure low friction sliding of the shuttle on the reed. The very tiny air gap formed between the magnets of the shuttle and the associated pole surfaces of the permanent magnets hardly detracts from the magnetic adhesive forces which, thus, in the return path are very high. This magnetic force is strong enough so that, even at substantial speed, the shuttles are not separated from the drive elements due to centrifugal force.
Before the shuttles can enter the shed in the portion adjacent the curved portion, and at the transition from the curved to the straight portion, it is necessary to guide the shuttle again on the guide reed. Upon high-speed movement of the shuttle, this leads to difficulty. A typical speed of the shuttle is about 1.4 m/sec. If adjacent shuttles are spaced from each other by, for example, 20 cm, seven shuttles will engage the reed or a run-on portion thereof each second. The continuous engagement of the shuttle with the reed causes noise and, additionally, subjects the slide surface to wear, particularly due to friction with the run-on region.