Slewing assembly
BACKGROUND OF THE INVENTION 
     The present invention relates to the improvements of the conventional slewing assembly, particularly to the improvements of the slewing assembly for a telescopic rod antenna. 
     The conventional slewing assembly generally comprises a cylindrical main body, a shackle member and a sleeve. The cylindrical main body includes a pedestal with a terminal to be connected to a radio set or the like and a hollowed cylindrical section for rotatably receiving the shackle member. Two slits are formed on the outer surface of the hollowed cylindrical section of the main body, wherein one of the two slits extends axially on the entire outer surface thereof, the other one extends around the outer circumference thereof at the end abutting against the pedestal of the main body. These two slits intersect at a right angle to constitute an integral cross slit. The shackle member comprises a forked portion for pivotally securing a telescopic rod antenna and a cylindrical section to be rotatably received in the hollowed cylindrical section of the main body, a plurality of grooves surrounding the outer surface thereof are provided for lubricating purpose. The cylindrical main body and the shackle member with the exception of the forked portion are encased by means of a sleeve when the cylindrical section of the shackle member is rotatably received in the hollowed cylindrical section of the main body. A groove interengageable with a preformed groove on the pedestal of the main body is then formed and caulked with pressing rollers on the outer surface of the sleeve. For prevention of disengagement, four-point punching holes pierced with four gimlets of the sleeve. 
     The conventional slewing assembly comprises the following disadvantages: 
     1. It is costly due to the sleeve is made of brass, 
     2. Manufacture and assembling of the components thereof are troublesome and tedious, 
     3. The chromeplated layer on the sleeve is susceptible to being stripped off when it is grooved and caulked with rollers or pierced with gimlets, 
     4. No smooth rotational torque is available because the circularity of hollowed cylindrical section of the main body is susceptible to being deformed when the shackle member is received therein. 
     Therefore, it is the object of the present invention to remove the above described disadvantages inherent in the conventional slewing assembly. The improvements are based on the experience of the present inventor who has been dealing with various antennas for more than twenty years. The slewing assembly of the present invention is constructed of fewer and simpler components in comparison with conventional slewing assemblies and thereby provides a much simpler structure. In this regard, manufacture and assembly of the components thereof become more easier and timesaving, as a result, mass production with higher quality makes the cost of the present slewing asembly greatly reduced. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other objects, features and advantages of the present invention shall become apparent as the description thereof proceeds when considered in connection with the accompanying illustrated drawings, wherein: 
     FIG. 1 is the exploded view and assembled view of the conventional slewing assembly for a telescopic rod antenna; 
     FIG. 2 is an enlarged sectionalized view of the conventional slewing assembly illustrated in FIG. 1; 
     FIG. 3 is the exploded view and assembled view of the present slewing assembly; 
     FIG. 4 is an enlarged sectionalized view of the present slewing assembly illustrated in FIG. 3. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     As illustrated in FIGS. 1 and 2, the conventional slewing assembly for connecting a foldable radio antenna to a radio, television or other electronic device by means of a universal joint generally comprises a cylindrical main body 1b, a shackle member 2b and a sleeve 3b. The cylindrical main body 1b includes a pedestal-like member with a terminal to be connected to a foldable antenna to a radio set (not shown) and a hollowed cylindrical section 11b for rotatably receiving the shackle member 2b. Two slits are formed on the outer surface of the hollowed cylindrical section 11b of the main body 1b, wherein one of the two slits extends a little more than a hemi-circumference axially on the entire surface thereof, while the other one extends around the outer circumference thereof at the end abutting against the pedestal-like member of the main body 1b, these two slits intersect at right angle to constitute an integral cross slit 12b. 
     The shackle member 2b comprises a forked portion for pivotally securing a telescopic rod antenna (not shown) and a cylindrical section 11b of the main body 1b, a plurality of grooves surrounding the outer surface thereof are provided for lubricating purpose. The cylindrical section 11b of the main body 1b and the shackle member 2b with the exception of the forked section are encased by means of sleeve 3b when the cylindrical section of the shackle member 2b is received in the hollowed cylindrical section 11b of the main body 1b of the main body 1b. A groove 413b interengageable with the preformed groove 13b formed and caulked on the outer surface of the sleeve 3b. For prevention of disengagement, four-point punching 414b must be provided in the groove 413b of the sleeve 3b as illustrated in 1-4 of FIG. 1. 
     Now referring to FIGS. 3 and 4 showing the constitution of the present slewing assembly. It is characterized that the present slewing assembly merely comprises a cylindrical main body 1a and a shackle member 2a. As illustrated in 2-1 of FIG. 3, the cylindrical main body 1a includes a pedestal with a terminal to be connected to a radio set (not shown) or the like and a hollowed cylindrical section 11a for rotatably receiving the shackle member 2a. 
     As illustrated in 2-2 of FIG. 3, the shackle member 2a comprises a forked portion containing a slot 24a and a screw hole 25a pivotally securing an extensile rod antenna (not shown) or the like and a hollowed cylindrical section 20a of the main body 1a, a plurality of grooves 21a surrounding the outer surface thereof are provided for lubricating purpose. Two slits are formed on the outer surface of the hollowed cylindrical section 20a of the shackle member, wherein one of the two slits extends axially on the entire outer surface thereof, while the other one extends more than a hemi-circumference around the outer circumference thereof at the end abutting against the flange 23a of the forked portion. These two slits intersect at right angle to constitute an integral cross slit 22a so that it is contractable and expandable. Slightly expand the hollow cylindrical section 20a of the shackle member 2a prior to engagement in the hollowed cylindrical section 11a of the main body 1a. When the hollowed cylindrical section 20a of the shackle member 2a is suitably received in the hollowed cylindrical section 11a of the main body 1a, as illustrates in 2-3 of FIG. 3, the opening margin 12a of the hollowed cylindrical section 11a above the flange 23a of the forked portion of the shackle member 2a is then pressed against the flange 23a. It is seen, with the above-described constitution, the shackle member 2a of the present slewing assembly may be easily engaged and firmly retained in the main body 1a, while it may be smoothly rotated without coming off the main body 1a. 
     In comparison with the conventional slewing assembly, the present slewing assembly is constructed of fewer and simpler components, thus products with higher precision and quality are obtainable, while the costs are greatly reduced. It is most clearly illustrated in FIG. 1, the conventional slewing assembly has the cross slit 12b formed on the hollowed cylindrical section 11b of the main body 1b, whereas the slit around the circumference thereof just extends a hemi-circumference of the hollowed cylindrical section 11b, the main body 1b may be elliptically squeezed to form a clearance 5b as illustrated in FIG. 2 when the hollowed cylindrical section of the shackle member 2b is received in the cylindrical section 11b of the main body 1b, because of the outside diameter of the cylindrical section of the shackle member 2b must be made slightly bigger than the inside diameter of the hollowed cylindrical section 11b of the main body 1b before the slit 12b is formed on the outer surface thereof in order to firmly retaining the shackle member 2 b in the main body 1b. In other words, the circularity of inner wall of the hollowed cylindrical section 11b of te main body 1b will extend radially (outwardly) and will be deformed when the cylindrical section of shackle member 2b is received in the hollowed cylindrical section 11b of the main body 1b. The main body 1b will be squeezed to an elliptical shape and formed a clearance 5b on the axially slitted portion when the shackle member 2a is received therein. In this regard, smooth rotation torque is not available due to the clearance 5b when the shackle member 2b is rotated with a rod antenna. The directional fluctuation of rotation torque can be measured with a Torque Meter in kg/cm when the shackle member 2b is rotated with a telescopic rod antenna. On the contrary, the present slewing assembly has the cross slit 22a formed on the hollowed cylindrical section 20a of the shackle member 2a, in addition, the outside diameter thereof and the inside diameter of the hollowed cylindrical section 11a of the main body 1a both have the same dimensions. When the shackle member 2a is suitably received in the hollowed cylindrical section 11a of the main body 1a with the opening margin 12a well pressed against the flange 23a of the shackle member 2a, the hollowed cylindrical section 20a of the shackle member 2a has been expanded in advance (with a tool) radially because of the cross slit 22a, as a result, the outer surface of the hollowed section 20a will be closely contiguous to the circular inner surface of the hollowed section 11a of the main body 1a as illustrated in FIG. 4, apparently, the shackle member 2a will be smoothly rotated in the main body 1a with steady and unfluctuated rotation torque. 
     While there is shown and described herein a specific structure embodying the invention, it will be manifest to those skilled in the art that various modifications and rearrangements of the parts may be made without departing from the spirit and scope of the underlying inventive concept and that the same is not limited to the particular form herein shown and described except insofar as indicated by the scope of the appended claim.