I don't really see the answer to original question. The answer is that if all that is varied is load, a higer load will cause higher stresses to develop in each part that transmits force from the piston to the wheels. Thus the proper answer to the origninal question is that both people in the...
Part of the fun in using older parts is searching for the manuals. I see the manual for the VFS5 on this page under the BDS5 section.
http://www.motionvillage.com/products/technical_documentation/obsolete.html