5~ This invention relates to a car coupler, and more particularly to a durable non-metallic wearplate disposed between the striker member and the coupler head of the car coupler. Standard railroad car couplers and strikers, or carriers mounted within the strikers, are normally provided with metallic wearplates to eliminate wear on these components and extend their useful life. Such wearplates are welded in position and difficult to remove and replace. The invention is directed to solving the problem by the provision of a cheaper, more economically produced non-metallic wearplate which wears well and is easily demountable for quick replacement with a new wearplate. According to the present invention there is provided a car coupler having a striker member with a coupler head having a shank member which extends therefrom through the striker member. A durable non-metallic wearplate is disposed between the members and is carried by at least one of the members which has a pair of opposing side walls with a pair of longitudinally extending grooves that (i) are recessed inwardly of the side walls towards each other, and (ii) have a pair of sloping surfaces which converge in a direction away from the wearplate. The wearplate has a channel-shaped cross-section and includes (i) a planar portion with marginal edges and (ii) a pair of flanges extending from the marginal edges of the planar portion for engaging adjacent side walls of the one member carrying the wearplate. The flanges have a pair of converging surfaces which rest against the converging surfaces of the grooves and free ends which are resiliently displaceable. W -- 1 -- : -~ Description of the Drawing The following description of the invention will be better understood by having reference to the annexed ~ drawing, wherein: ; Fig. 1 is a plan view of a conventional E coupler employing a wearplate made in accordance with the invention; Fig. 2 is a side view of the coupler; Fig. 3 is a vertical section of a striker that is used with the E coupler and employs a similar wearplate, also shown in section; Fig. 4 is a section of the coupler viewed from the line 4-4 of Fig. 2; - Fig. 5 is a section, similar to that of Fig. 4, illustrating a different embodiment of the invention; and Fig. 6 is a perspective view of still another embodiment of the invention. ' :.; ' .: . ~ .1 - la - Description of the Invention With reference to Figs. 1-3, there is shown an E-type coupler 10 comprising a head 11 with coupling means 12, and a shank 13 which extends from the coupler head 11 for insertion in an opening 14 of a striker 15. A wearplate 16 is detachably mounted on the shank 13 of the coupler lO for engaging a similar wearplate 17 that is detachably mounted on the striker 15. The wearplates 16,17 are non-metallic, being composed of any suitable elastomeric material, e.g. nylon, urethane, or an ultra-high molecular weight polymer. Such materials must be sufficiently durable to resist hard wear normally experienced by conventional metal wearplates. An excellent material is a plastic made and sold by the Holland Company of Illinois under the trademark Hollube. Hollube plastic, as indicated in U.S. Patent No. 4,055,254, is an ultra-high molecular weight polymer which is preferably a polyethylene having a molecular weight in the range of from 2,000,000 to 10,000,000. This particular plastic has a coeffi- cient of sliding or dynamic friction with steel of about .02. The non-metallic wearplates 16,17, are detachably mounted on the coupler 10 and striker 15 by any suitable means which can be similar and designed to frictionally hold the wearplates to the components. The following description of such mountings will be explained in relation to wearplate 16, it being understood that identical means can be used to mount the wearplate 17 on the striker 15. With reference to Fig. 4, the wearplate 16 is channel- shaped, having a planar portion 18 with upstanding side flanges 19,20. The planar portion 18 of the wearplate 16 covers the adjacent underside 21 of the coupler shank 13, while the side flanges 19,20 extend upwardly along the adjacent lower sidewalls 22,23 of the coupler shank 13. A pair of bulbous portions 24,25, ~8~iG~ acting as stops, are disposed adjacent the free ends 26,27 of the side flanges 19,20 of the wearplate 16. The stops 24,25 project inwardly of the side flanges 19,20 towards each other and are designed to be received into a pair of matingly configured openings or grooves 28,29 that are recessed longitudinally in the lower sidewalls 22,23 of the coupler shank 13. The stops 24,25 of the wearplate 16 coact with a pair of abutments 30,31, formed in the lower sidewalls 22,23 of the coupler shank 13 adjacent the grooves 28,29, to frictionally hold the wearplate 16 adjacent and in abutting relation to the underside 21 of the coupler shank 13. The stops 24,25 of the wearplate 16 are re- siliently depressable away from each other so that the wearplate 16 can be readily mounted on the underside 21 of the coupler shank 13. With reference to Figs. 5 and 6, the wearplate 16 is, likewise, channel-shaped, having a planar portion 35 with up- standing side flanges 36,37 which are not essential, since the means for fastening the wearplate 16 to the coupler shank 13 are located intermediate the side flanges 36,37. A plug 38 extends centrally of the planar portion 35 of the wearplate 16 inter- .lediate the side flanges 36,37. The plug 38 is insertable in an opening 39 formed in the underside 40 of the coupler shank 13. The plug 38 may be circular, in section, or it may be elongated and rectangular, in section, as best seen in Fig. 6, depending on the shape of the opening. In either case, the plug 38 is provided with an enlarged head portion 41 which is divid~d into two segments 42,43 by at least one transversely extending slot 44. The outside diameter of the head portion 41 of a circular sectioned plug 38 is greater than the inside diameter of a circular opening 39. Likewise, the overall width of the enlarged head portion 41 of a rectangular sectioned plug 38 is greater than the width of a rectangular opening 39 Measured transversely of the coupler shank 13. --3-- A pair of stops 45,46 are provided on the head segments 42,43 for interlocking engagement with a pair of mating abutments 47,48 disposed adjacent the opening 39 in the underside 40 of the coupler shank 13. The head 41 is bifurcated by the slot 44 so that the stops 45,46 are resiliently depressable towards each other to permit insertion of the plug 38 into the opening 39. A plurality of longitudinally spaced circular openings 39 can be provided in the underside 40 of the coupler shank 30, depending on the length of the wearplate 16 and the number of circular sectioned plugs 38 required to hold the wearplate firmly in place. Thus, there has been provided a non-metallic wearplate and means for detachably mounting the wearplate on the shank of the coupler and striker or carrier resiliently mounted within a striker. In cases where a single wearplate is used between the striker of carrier and coupler, the wearplate is normally secured to the coupler, since this is the most desirable part to protect. The friction-type fittings of ~igs. 4-6 can be used in combination in cases where desired. --4--