RE: (ET) linear actuator power steering?

["Elie, Larry \(L.D.\)" <lelie ford com>]

In real life, the steering rate was not 'limited'; the actuator was 'fast' 
compared to human inputs.  
In normal power steering, it's the same situation; very few drivers can 
turn the wheel faster than 
the pump can supply volume.  Until you reached that point, it felt like a 
variable rate.  If you 
used a wimply actuator, the actuator rate would make the steering feel 
limited.

Larry Elie


-----Original Message-----
From: elec-trak-bounces cosmos phy tufts edu
[mailto:elec-trak-bounces cosmos phy tufts edu]On Behalf Of Chris
Tromley
Sent: Thursday, July 01, 2004 10:24 AM
To: 'Elec-Trak Tractor'
Subject: RE: (ET) linear actuator power steering?


Larry Elie wrote:

> Actually, one can (and I have seen it done) mount a two 
> direction momentary toggle on the shaft requiring 
> turning, and affixing the toggle portion to the steering 
> wheel.  IF there is just a tiny bit of play in 
> the system, when you turn the wheel to the left for example, 
> the toggle and the actuator turns left until 
> the wheel and shaft positions agree, at which time the 
> actuator stops.  It works well.  It has no real tactile 
> feedback.  The important part is the mechanical reference is 
> the SHAFT REQUIRING TURNING and NOT ground.  A 
> friend of mine did this for a very early electric power 
> steering in 1969.  

Hi Larry,

This is a clever approach.  My problem with this concept, though, is
that having a fixed steering rate under all conditions (or limited range
of steering rates) is a pain.  I already don't like the 7-step hand
lever for speed control (I'd *hate* a 4-step).  Limiting my steering
rate would be push me over the edge.

As I approach a tree (at a fixed speed), I need to whip the steering
around to full lock quickly to mow around the tree.  Other times I need
to make a larger radius turn, so I crank the wheel more slowly.  Having
the steering turn at one speed determined by the actuator would not only
be aggravating, it could be unsafe.

Chris



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