Ball box
THE INVENTION 
     This invention relates to a ball box construction, and particularly to a ball box with continuous ball races located in a cage. In such a design, the axially directed return channels adjacent to each other are provided in pairs in the load-free zone, each channel of a pair separated from the other by means of an axially directed cross-piece. 
     Ball boxes of such designs are known. The race supports located in the loaded zone are designed such that, in each case, the balls of two ball races can roll side by side. In the region of the front sides of the ball box, the balls are deflected from the loaded zone into the return channel or vice versa. 
     The main object of the present invention is to provide an improved ball box construction. 
     A further object of the invention is to improve the supporting capacity of a ball box of the type described above without impairing the satisfactory circulation of the balls. 
     In accordance with the present invention, the present invention provides a ball box construction achieving the foregoing objects by providing a slight separation between the return channels sufficient to prevent contact of the balls in adjacent ball races, the width of the cross-piece providing such separation measuring zero in the circumferential direction at the level of the ball pitch circle in the return channels. The ball box formed according to the innovation thus meets the requirement of being able to contain a maximum number of race supports at the circumference of the ball box. In this way, the number of balls and therefore the supporting capacity of the ball box is increased. Furthermore, as a result of the space gained by the small width of the cross-piece, larger balls can be used, having further favorable effect on the supporting capacity. 
     In a preferred embodiment of the invention, the cross-pieces are provided with tapered cross-section in the direction of the ball pitch circle. 
     Alternatively, the objects are achieved and the balls prevented from falling out of the return channels by providing the radially outer cross-pieces in the form of wires contacting the balls with both ends of the wires being attached to the cage. 
    
    
     Further objects and advantages of the present invention will become more apparent from the following more detailed description of the embodiments, taken in connection with the appended drawings, wherein: 
     FIG. 1a is a cross-section through a ball box in accordance with the invention; 
     FIG. 1b is a cross-section through a modified embodiment of the invention; 
     FIG. 2a is a top view of the ball box according to FIG. 1a; and 
     FIG. 2b is a top view of the ball box according to FIG. 2a. 
    
    
     Referring now to the Figures, the ball boxes shown are used for the axial movement of an axle or shaft in a housing or, conversely, of a housing on an axle. For this purpose, a cage 1 which may be made, for example, of plastic or like material, is provided wherein two rows of balls 2 circulate. In the loaded zone, the balls 2 roll off in pairs on common race supports 3, which are made of steel. The race supports 3 are inserted in openings 4 of the cage 1 and are braced against the outer circumference 5 in the bore of a housing 6. The balls 2 in the loaded zone project radially inward from the cage 1, so that they can contact an axle (not shown). 
     Provided in the load-free zone for the balls 2 are a pair of adjacent, axially directed, return channels 8, open in the direction of the outer circumference of the cage 1. The return channels 8 are separated from each other pairwise by axially directed cross-pieces 9. 
     During circulation, the balls 2 are deflected in the region of a first front side of the ball box by deflecting channels 10. The channels 10 deflect the balls 2 from the loaded zone into the load-free zone, i.e., into the return channels 8. In the region of the other front side of the ball box, they are again conducted by the deflecting channels 10 from the return channels 8 into the loaded zone. 
     In order to be able to house a maximum number of continuously circulating balls in the ball races, the cross-pieces 9, which separate the adjacent return channels 8 from each other, are made in such a way that the balls of two adjacent ball races are just able to avoid contact at the optimum clearance. In this way, the space available in cage 1 is utilized in such a way that the deflecting radius in the deflecting channels 10 can be optimally designed in accordance with the diameter of the balls 2, and the number of races maximized. 
     In the embodiment according to FIGS. 1a, and 2a the cross-pieces 9 arranged radially on the inside and outside are tapered in the direction of the ball pitch circle 11. Their width, measured in the circumferential direction, is zero at the level of the ball pitch circle 11. 
     In the variation shown in FIGS. 1b and 2b the radially outer cross-pieces 9 consist of wires 9a, both ends of which are attached to the cage 1, and which prevent the balls 2 from falling out of the return channels 8. 
     Further variations and alternatives will be apparent to those skilled in the art.