Technical Field The invention relates to a track car system comprising a track and a track car displaceably arranged on the track in the longitudinal direction thereof by means of a plurality of rolling bodies, on opposed sides said track provided with longitudinal and substantially V-shaped track grooves having two track groove faces arranged substantially perpendicular to each other, and said car provided with two interspaced continuous paths each comprising a substantially V-shaped, longitudinal car groove facing the respective track groove and having two car groove faces arranged substantially perpendicular to each other, and wherein the longitudinal car grooves are such interspaced that a plurality of rolling bodies arranged in each of the continuous paths are in contact with and thus roll and/or slide on the track groove faces and the car groove faces and consequently circulate in the continuous paths at displacement of the car relative to the track, each of the continuous paths comprising a return passage with direction-changing portions connected to the car groove.

Background Art US-A-4,719,869 discloses a track car system of the above type, in which the track car serves as a sheet car and wherein all of the rolling bodies are balls.

Furthermore US-A-4,735,514 discloses a track car system of the above type in which the rolling bodies in the continuous paths are rollers arranged in a parallel arrangement, ie. the axes of the rollers in the car groove are mutually parallel. A track car system comprising a pair of continuous paths with rollers in a parallel arrangement is only able to receive a load in one main direction, ie either a thrust load or a pulling force, for which reason two pairs of continuous paths are necessary for receiving both thrust load and pulling force, as shown in US-A-4,735,514.

Finally US-A-4,688,950 and US-A-4,511,189 disclose a track car system of the above type in which each endless path only accommodates rollers arranged in a so-called cross arrangement, ie they are arranged such that their axes intersect each other. As a result the track car system is able to receive both thrust load and pulling force, but only half of the rollers carry loads in each of the two relevant directions.

Brief Description of the Invention The object of the invention is to provide an improved, simple and reliable track car system of the above type which is able to receive both thrust load and pulling force.

The track car system according to the invention is characterised in that rolling bodies in form of both balls and rollers are provided in each of the continuous paths, and that the rollers have a diameter substantially equal to the diameter of the balls and a length shorter than the diameter of the balls.

As a result, regardless of the load direction, the balls always roll on the track and the car, respectively, and the end faces of the rollers in principle never slide thereon.

Increased bearing capacity is also obtained in the main load direction in relation to a track car system with the rollers arranged in a cross arrangement (in which only every other roller carries load), both the rollers and the balls being load-carrying, reduced bearing capacity, however, being obtained in the opposite direction, as only the balls carry loads in this direction. In practice these properties are in high demand. Thus a sheet car on a sailing boat is subjected to a heavy pulling force, but virtually no thrust loads. On the other hand mast track cars for sail battens, so-called full batten cars, are subjected to a heavy thrust load and less to a pulling force.

Moreover by using both rollers and balls in the continuous paths, the rollers more easily circulate in the curved direction-changing portions of the return path without tilting or being jammed which tend to happen when only rollers are used.

Consequently the displacement of the car relative to the track is facilitated.

According to the invention the length of the rollers may be 1 to 10%, preferably 3 to 7 % less than the diameters thereof. In practice excellent results have been obtained with rollers having a length about 5 % less than their diameter.

According to a preferred embodiment of the invention the V-shaped grooves of the tracks are arranged symmetrical about the longitudinal mid-plane of the track and the V-shaped grooves of the car are correspondingly arranged symmetrical about the longitudinal mid-plane.

Furthermore according to a further development of the said embodiment each of the track groove faces and correspondingly each of the car track faces may form an angle substantially of 45 ° with the longitudinal mid-plane. However it should be understood that also angles other than 45 ° may be used.

Moreover according to the invention the continuous paths of the car may be arranged substantially in a common plane perpendicular to the longitudinal mid-plane of the track, whereby it is possible to provide a very flat car.

Furthermore according to the invention each of the continuous paths of the car may be arranged substantially in a plane forming an acute angle with the longitudinal mid-plane of the track and is substantially perpendicular to one of the track groove faces of the respective track groove. As a result it is possible to provide a narrow car.

Moreover according to the invention the rolling bodies in each of the continuous paths may alternately be a roller and a ball.

According to another embodiment of the invention to increase the load-bearing

capacity of the main load direction at least two, preferably two or three, rollers may be provided between two successive balls in each continuous path.

Brief Description of the Drawings The invention is explained in detail below with reference to the drawings, in which Fig. 1 is a diagrammatic cross-sectional view through a track car system according to the invention primarily intended to receive thrust load, Fig. 2 is diagrammatic sectional view along the line II-II in Fig. 1, Fig. 3 is a diagrammatic cross-sectional through a modified embodiment of the track car system shown in Fig. 1, this embodiment being adapted to primarily receive pulling force, Fig. 4 is diagrammatic sectional view along the line III-III in Fig. 3, Fig. 5 is a diagrammatic cross-sectional through another embodiment of a track car system according to the invention, this embodiment being adapted to primarily receive pulling force, and Fig. 6 is a sectional view along the line VI-VI in Fig. 5.

Best Mode for Carrying Out the Invention The track car system according to the invention shown in Figs. 1 and 2 comprises a track 1 and a track car 2 displaceably arranged on the track 1 in the longitudinal direction thereof by means of a plurality of rolling bodies. The track 1 is shaped as a hollow, substantially box-shaped section with a bottom face 3, an upper face 4 and

two opposed side faces 5,6. The track is symmetrical about a longitudinal mid-plane L and in each lateral face provided with a longitudinal and substantially V-shaped track groove 7,8 having two track groove faces 9,10; 11,12 arranged substantially perpendicular to each other. When seen in a cross-sectional view the track car 2 is shaped substantially as a short-legged U and each leg of the U is provided with a continuous path 13,14 for the rolling bodies. Each continuous path 13,14 is formed of a longitudinal car groove 17,18 provided in the inner side face 15,16 of each leg, a return passage 19,20 extending parallel thereto and having circular end portions 21,22; 27,28 connecting the return passage 19,20 with the car groove 15,16. The two continuous paths 13,14 are arranged substantially in a common plane, which is perpendicular to the longitudinal mid-plane L, whereby the track car 2 may be of a comparatively low height. The car grooves 17 are situated opposite the respective track grooves 7,8 and are substantially V-shaped with two car groove faces 23,24; 25,26, which are arranged substantially perpendicular to each other. The car grooves 17,18 and the track grooves 7,8 define a longitudinal passage substantially square in cross section. The return passages 19,20 and the end portions thereof have substantially the same square cross section. At its outer rim each of the lower car groove faces 24,26 is provided with a protruding ledge 29,30 retaining the rolling bodies in the grooves.

The rolling bodies are formed of a plurality of alternating balls 31 and rollers 32 in each of the continuous paths 13,14. The diameters d2 of rollers correspond substantially to the diameter dl of the balls, while the length h of the rollers is slightly less than their diameter d2 and thus also than the diameter dl of the balls. In fig. 1 the cylindrical surfaces of the rollers are illustrated by means of lines parallel to the roller axis. The rollers 32 thus roll on the lower track groove faces 9, 10 and the upper car groove faces 23,25 when the car 2 is displaced along the track while being subjected to a load in the direction shown by the arrow P. The balls 31 also roll on the said faces. When the car is subjected to a load in the direction opposite the direction of the arrow, the balls 31 roll on the groove faces 9,23; 12,

26 at displacement of the car. When the car 2 is displaced, the end faces of the rollers slide on the adjacent groove faces, but as the length h of the rollers is less than the diameter dl of the balls, virtually no friction occurs. At a load in the direction of the arrow P, which is the main load direction, both the rollers and the balls are load-carrying, while the only the balls carry are load-carrying when the car 2 is subjected to a load in the direction opposite the arrow P.

Figs. 3 and 4 show a modification of the track car system shown in Figs. 1 and 2.

The modification only differs from the previously described system in that the rollers 32 have been turned 90° in relation to their position in Figs. 1 and 2 such that their cylindrical faces roll on the upper track grooves faces 11 and 12 and the lower car groove faces 24 and 27 when the car 2 is displaced along the track 1 while being subjected to a load in the direction of the arrow T which is the main load direction.

The shown track car system thus allows for a change of the main load direction from the vertically downward direction P towards the track 1 as shown in Fig. 1 to the vertically upward direction T away from the track 1 as shown in Fig. 3 merely by changing the orientation of the rollers 32. All other features of the two track car systems are completely identical.

Figs. 5 and 6 illustrate another embodiment of a track car system according to the invention adapted to receive a heavy pulling force in the direction of the arrow T and minor thrust loads in the direction opposite the arrow. The track car system comprises a track 51 and a track car 52 provided with two continuous paths 63,64, in which a plurality of rollers 32 and a plurality of balls 31 are accommodated, two rollers being provided between two successive balls.

The track 51 is a hollow section having a bottom face 53, an upper face 54 and two side faces 56. Each side face is provided with a V-shaped, longitudinal track groove 57,58 corresponding to the track grooves 7,8 described above with reference to Figs. 1 and 2. In a cross-sectional view the track car 52 is U-shaped and the

continuous paths 63,64 are provided in the respective legs. The continuous paths 63, 64 correspond essentially to the continuous paths 19,20 described above with reference to Figs. 1 and 2 with the exception that they are arranged in a plane forming an angle of 45 ° with the longitudinal mid-plane L of the track 51 and the car 52. Each of the continuous paths 63,64 thus has a V-shaped car groove 67,68 arranged opposite the respective track grooves 57,58. The dimensions of the balls 31 and the rollers 32 are the same as described above with reference to Figs. 1 and 2, and the rollers are orientated in the same manner as the rollers in Figs. 3 and 4, ie the cylindrical surfaces thereof roll on the groove faces 61,74; 62,76 when the car 52 is displaced along the track 51 while being subjected to a load in the direction of the arrow T, which is the main load direction.

The car 52 is further provided with two additional continuous ball paths 90,91 in which a plurality of small balls 94 is accommodated. Each ball path comprises an open ball groove 92,93 which is open towards the upper face 54 of the track. When the car 52 is subjected to a load in the direction opposite the arrow T, the small balls 94 carry the load jointly with the balls 31 in the continuous paths 63,64 and circulate in the respective additional continuous paths 90,91 when the car 52 is displaced.

The parts of the track car system, ie the track, the track car, the rollers and the balls may be made from a number of different materials and by means of various processes. A person skilled in the art will easily be able to choose the most advantageous combination of materials. However, it should be noted that advantageously the track may be made as an extruded aluminium sectional bar which is hard-anodized (ie having a hard anodic coating) and cut to the desired length. Correspondingly, the car may be made from an extruded aluminium sectional bar which is subsequently processed for the formation of the continuous paths and hard-anodized. The balls and the rollers may advantageously be made of plastics, such as polyamide imide.