Je to klasicky pascal nebo neco vyssiho - Delphi, FreePascal?
Univerzalni reseni je nacist do jedne promenne, pakpomoci POS, COPY a DELETE rozdelit do 3 promennych

var
  s, s1, s2, s3: string;
begin
  s := 'Sdsdf" "654654" "455';
  s1 := Copy(s, 1, Pos(' ', s) - 1); 
  Delete(s, 1, Pos(' ', s));
  s2 := Copy(s, 1, Pos(' ', s) - 1);
  s3 := Copy(s, Pos(' ', s) + 1, 255);