by the directional arrows u201c d u201d for selective positioning with respect to the mounting apertures of the machine one preferred mounting element 20 contemplated by the present invention is the bolt apparatus detailed in fig4 the preferred bolt apparatus includes a bolt 22 an enlarged washer 24 threadably engaged to the bolt and a coil spring 26 which is connected to the washer as appreciated the components of the bolt apparatus may be assembled prior to mounting to the respective channel the bolt apparatus is inverted and positioned within the channel of the longitudinal rail with the washer 24 confined within the lips 16 of the u shaped rail in this relation the bolt 22 may traverse within the channel for positioning with respect to the machine mounting apertures preferably the enlarged washer 24 is in the form of a parallelepiped although other shapes and dimensions are envisioned as well in the preferred embodiment there exists a clearance between the outer edge of the washer and the internal surface of the longitudinal rail to also permit lateral movement indicated by the directional arrows u201c t u201d fig2 of the bolt 22 within the rail this lateral movement permits lateral adjustment of the bolt.