Abstract: A variable rate fertilizer spreading apparatus for spreading a precise amount of multiple types of fertilizers upon a field based upon a location in the field. The system comprises a controller accessing a soil map indicating the type of soil for each portion of the field, several fertilizer maps storing the desired fertilizer level of each of the fertilizers stored in product bins on the tractor, and several status maps each indicating the current fertilizer level at various locations of the field to be fertilized. By accessing the speed of the tractor via a speed indicator, and ascertaining the location of the tractor in the field via a position locator, such as an LORAN or GPS system, an expert system determines the dispensing rate of each of the fertilizers based on the various maps and the position and speed indicators such that the proper dispense rate of the fertilizers from bins is set to attain the desired level of fertilizers.

Abstract: A strobe light, oriented directly over a railroad track rail and at a 45.degree. angle to the horizontal, projects a light line across the rail. A pair of cameras oriented directly over the rail view the light image on the rail. The light lines reflected from the foot of the rail provide a reference for numerically describing the profile of the railhead. The measured rail profile is compared to an ideal rail profile. The results of the comparison are used to position grinding modules for grinding the rail to a preferred profile.

Abstract: A table and attached bench support structure is foldable between an open erected position and a closed storable position. The table support mechanism comprises pivotally interconnected top brace, leg brace, bench leg, bench support member and table leg cooperating together to support both the table top and the bench seats. The table and bench mechanism may fold together for storage of the table, or the benches may be removed and the table separately folded for storage. The volume of the folded table is approximately one-eighth the volume of the fully erected table.