The only way to control the speed of a forklift is to limit the forklift via a speed limiter device. As we all know forklift drivers seem to leave their brains at home when they hop on a forklift and comapnies cannot rely on the driver to do the right thing. In Australia there is a company that not only install a speed limiter but they install a speedo so the driver can see how fast he is going. they have a site at www.waresafety.com.au