idler sprockets 19 20 21 and 22 and back to drive sprocket 23 as seen clearly in fig4 extending between and secured to the pairs of pusher bar chains 30 are a plurality of spaced pusher bars 31 the spacing between these pusher bars is such that without internal adjustments the cooler 10 of the present invention will accommodate a wide range of different size containers the track rails forming the upper tier 15 are curved downwardly approximately 90 degrees adjacent idler sprocket 20 at one end and are curved downwardly adjacent idler sprocket 19 to a point just above bottom tier 18 at the other end as can clearly be seen in fig4 the track rails forming tier 16 begin immediately above top tier 15 at the end of idler sprockets 20 and extend downwardly a little over 90 degrees at the end adjacent drive sprockets 23 the track rails forming tier 17 begin immediately above tier 16 adjacent the end of drive sprockets 23 and extend downwardly slightly over 90 degrees slightly at the end adjacent idler sprockets 22 finally the track rails of tier 18 begin immediately above tier 17 adjacent the end of sprockets 22 and extend upwardly on the outside of the pusher bars 31 to a point adjacent upper tier 15 at the.