Couldn't find much on those springs Harry, they seem to be lost to time. Might as Dad, see what he knows about them
Here's all I could find
http://books.google.com/books?id=Ow5aAAAAYAAJ&pg=PA180-IA23&lpg=PA180-IA23&dq=Schuler+spring+buckboard&source=bl&ots=gYXHpFCJ5V&sig=2FMFYPPVgqV3jihP0oOK8ofw4rE&hl=en&sa=X&ei=u-GiUe_TD6nOyQGLv4DICg&ved=0CGsQ6AEwBw#v=onepage&q=Schuler%20spring%20buckboard&f=false