corners as at 46 referring back to fig2 four conventional spikes 50 pass through holes 44 and secure the assembly 18 to the tie 14 attached to plate 30 is a shoulder 52 this shoulder 52 includes a base 54 having a somewhat square configuration with sloping sides as at 56 the base 54 also has a flat bottom surface 58 with a boss 60 extending downwardly from the surface 58 the boss 60 has the same shape and size as hole 44 the boss 60 has an outer surface with a circumferential groove 64 the shoulder 52 further includes a clamping wall 70 having a somewhat cylindrical outer surface 72 terminating in a sloping edge 74 the clamping wall 70 is sized and shaped so that when the shoulder 52 is attached to the plate 18 the slopping edge 74 abuts an upper portion of sloping wall 38 a on the plate the clamping wall 70 also includes an inner surface 76 this inner surface 76 has a partial cylindrical shape and forms with wall 38 a a horizontal hole 78 in one embodiment the clamping wall 70 is provided with an end portion 80 on the inner surface 76 the end portion 80 is formed with a semicircular cutout 82 this cutout forms an opening 84 for hole 78 in an alternate embodiment shoulder 52 a also shown in fig4 end portion 80 a extends across inner surface 76 a so when the shoulder is.