At 09:43 AM 29/05/2011, Keith wrote:
>I converted the Curtis PB-6 successfully for 3-wire operation using
>my pedestal throttle (cable)control. The electronics are now weather
>protected, and the mechanical element provides much better control.
G'day All
I recently faced a similar issue - grafting a Curtis controller onto
a stand-up forklift, so the joystick had to be spring
return-to-center with 5k each side of center. I was fortunate to have
the mechanism of the original joystick to work with, but the Curtis
controller of course needs 0 to 5k resistance, which in a
bi-directional joystick represents a problem.
To overcome this, I bought a good quality "stopless" potentiometer
(one that is made without a mechanical stop, so to find the end
positions you need to measure it). It wasn't cheap, a sealed,
ceramic-substrate potentiometer designed for industrial applications
(about $40) with a manufacturers' life span given as 1 million
rotations. I was able to select one that was able to be set up with
'zero' sitting in the 'dead' zone between the ends, giving me an arc
that used the first 5k worth of the track each side. Joining the two
track ends together gave me 0 to 5k each side of center, which if the
pot value had been high enough (i.e. used a short part of the ends of
the tracks) would have been the end of it, but my pot arc moved too
far so the track to the "other" end was noticeably in circuit. I had
to prise the back off the pot, cut the track and glue the back onto
the pot again.
The joystick already has cams that operated the forward and reverse
microswitches, but if it hadn't it would not have been hard to add them.
In the context of a boat, it would be possible to get one of these
joysticks (from a scrap dealer that dismantles forklifts), and remove
the springs to make it stay put, although a friction element may be
needed to stop it moving if the boat is prone to jumping about. The
microswitches provide a noticeable center detent, wether it would
have been sufficiently solid a detent would depend on the user, I suppose.
This may help someone.
Regards
[Technik] James
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