right or forward as indicated by arrows 64 66 and 68 respectively alternatively it might be desirable to move the platform 45 degrees to the left as indicated by arrows 70 or to the right shown by arrow 72 the adaptability of the present design in permiting movement in various directions is achieved by the circular array of tapped holes 34 as more clearly seen in fig8 thus by chosing the appropriate pair of holes 34 the roller 36 may be oriented in any one of four positions to permit the platform to roll in any one of the four directions shown by fig9 when a platform is chosen for a particular installation a decision is made on the desired direction of rolling and the axles of the roller assemblies are accordingly mounted in a pair of holes 34 referring now to fig1 and 14 there is shown a modified embodiment of the invention in which the movable platform is formed in two sections the elements of fig1 and 14 that correspond to the above described elements are similarily numbered and carry the designation a thus the platform 10a has the support strips 20a and 22a which serve to mount roller assemblers of the type above described however in this embodiment the platen 18a is divided into two sections and an additional support strip 22b is provided it is understood that in this embodiment it is contemplated that the supporting machinery consists of two sections 16a and 16b and in which case it may be.