pallet 5 is in a new or unsagged condition after thermal sagging occurs in the pallet the longitudinal axis of the axle assumes the position 34 l 1 34 which is offset from the horizontal by some angular value designated 34 u03b8 34 in fig9 the bushing 80 and its concave seat 82 due to the spherical shape permit the axle 42 to angularly sag while still allowing the pallet to rotate and tilt downwardly and upwardly as required in the discharge operation depicted fig3 this same thermally induced sagging phenomenon also detrimentally affects the second pair of rearwardly disposed fixed axles 62 and 64 the sagging causes a potential problem however only in axle 62 and its inner wheel 70 since the outer wheel 72 is unrestrained and can freely accommodate the sagging in order to anticipate potential pallet sag and attendant axle deflection on the restrained inner axle 62 the slotted areas 102 of the guide block 100 are provided with convex shaped seating surfaces 106 the convex surfaces permit angular deflection between the slots 102 and the respective alignment lugs 104 and prevents binding therebetween which could interfere with the free tilting of the pallets during the discharge operation the rear pallet wheels 70 and 72 are mounted on the fixed pair of second axles 62 and 64 respectively.