From: raveling@Unify.com (Paul Raveling)
Subject: Re: Very poor human interface on Kubota tractor
Organization: Unify Corporation (Sacramento)
Date: Tue, 14 Apr 92 20:08:51 GMT

In article <RWK.92Apr13000253@taunton.crl.dec.com>, rwk@crl.dec.com (Bob Kerns) writes:
> 
> Let me put this into context (but not justify it!).  My
> purpose here is just to explain the situation for all
> the folks who've never been near one, and illustrate the
> different design constraints.  I don't mean this to
> detract from the validity of your point at all.

	Well said.

> Also, realize that tractors are not assumed to be used
> by unskilled operators.  They're recognized as dangerous
> heavy equipment, and I know I got a lot of safety
> instruction and supervision before I was ever allowed to
> even go near one, let alone operate one.

	Maybe times have changed a bit.  The first motor vehicle I ever
	operated was a tractor, my Uncle John's Farmall.  Back in
	the '50's SOP around Lake Wobegon (alias Hillman, Minnesota)
	was to have the kids drive the tractor.  Adults and teenagers
	did things like pitching hay bales that weighed 75 to 100 pounds
	up to a 3-high stack on the wagon that the tractor was hauling.

	My observation was that typical farm families taught kids
	how to use farm machinery responsibly and safely at an early
	age.  Anyone who had to lay in hay for 18 cows over a long winter,
	and had to do it between summer thunderstorms, would almost
	certainly put the kids to work on it.  Besides, that was one of
	the most entertaining things for kids to do on a remote farm :-)

	Anyway, equipment was built an a straightforward utilitarian way,
	without as much attention to human factors as we might supply now
	but also with no nonsense in the design.  It wasn't that tough
	to learn how to operate it and what the potential dangers were.

	Emphasis here for crossover to other areas of human engineering
	should go to "NO NONSENSE IN THE DESIGN".

> 	  Braking involves two pedals and a lever.  The pedals apply brakes 
>    separately to the left and right rear wheels.  ...

	Another example of separate braking is wheel brakes on aircraft.
	These don't have any form of interlock to connect them together
	and safe operation demands that there be none.

>    positions, this being a Diesel.  The manual states that turning the key to
>    "stop" will usually, but not always, stop the engine, and a separate
>    emergency off pull switch is provided if the key doesn't work.
> 
> I'm a little surprised that the key switch turns off the engine at all...

	The question of shutting off a diesel is one where they probably
	put in a disclaimer that "it may go dieseling on" to give them
	legal protection from claims that the product is faulty.  This
	is natural with diesels.

	Some of Kubota's other warnings about locked differentials and
	locked brakes would be a combination of legal protection and
	communicating legitimate info that people need to know for
	safe operation.  I wonder if the interlock for setting the
	parking brake is a preventive measure to assure that it's
	not used when the tractor is in motion; perhaps it engages
	abruptly, which would make it dangerous to use when in motion.


	BTW, I haven't really looked at tractors for about 3 decades,
	but some had gear shifts that could be modestly challenging.
	Just imagine the shift pattern for going up through 11 forward
	gears... 


------------------
Paul Raveling
Raveling@Unify.com