Us Four Wheel Drive Caldwell Vale. In 1907 Felix Caldwell and Norman Laurie Caldwell of South Australia applied for a patent to cover Improvements in and connected with driving and steering motor propelled vehicles . Drive to both front and rear axles is by propeller shafts and bevel gears.
Half shafts carry the drive along live axles to open-style steering knuckles.
Modern looking universal joints allow steering, and the drive continues through hollow stub-axles to drive fully floating hubs and the wheels. Front and rear wheels are shown steering in opposite directions. A later patent application from Felix Caldwell in 1912 covers Improved power steering gear for heavy motor driven road vehicles . The steering wheel indicates an intended direction for the road wheels. The difference between the actual and intended directions is used to engage cone clutches which bring power assistance into play to turn the steering arms in the intended direction.