Re: Electric steering
Doug's comment got me thinking about the last bastion of hydraulic fluid, the brakes. There will always be a need for highly reliable, mechanical brakes but it isn't clear that it has to be hydraulic operated. Before hydraulic brakes, they were mechanical and though hydraulic brakes were an improvement, it may be time for this last bastion to be replaced by electrically operated brakes.
Two approaches come to mind: directly actuated shoes and 4-wheel motor/generators. Of the two, I like the 4-wheel drive solution since it also provides improve drive as well as braking. However, directly actuated shoes would also work by elimination of hydraulic lines and advanced traction control.
For those worried about reliability, truck air brakes offer a solution. Truck brakes have a spring that is 'unloaded' by air pressure, much like trains. When the pressure is reduced, the spring actuates the brakes. The failure mode is to apply the brakes. A similar, magnetic latch could be used in an electro-mechanical brake. Loss of power would simply release the spring to apply the brakes and stop the vehicle.
Hydraulic brakes have an 80 year history but electronics and stolid state control have reached a point where designers may be able to do better.
Bob Wilson
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