Is there a direct way to export .skp files to .pdf format.
Converting SketchUp Documents directly to Adobe Portable Document Format (.skp to .pdf conversion) shouldn't be too difficult. You can export SketchUp 3D models (.skp) to .pdf format using a virtual PDF printer, or via the 'Export to PDF' function in one of the 3D tools that support SketchUp formats.
Obviously, your best bet remains the actual SketchUp software itself, which is capable of exporting its .skp files as .pdf documents.
A commercial online CAD converter
A 3D general-purpose modeling program