john taylor wrote:
> Listers,
>
> In recent strings there have been several comments about lock nuts and
> lockwashers.
>
> PLEASE..... think about it... LOCK WASHERS DO NOT WORK. In order for them to
> have a spring effect the fastner must be loose.
>
>
Well, this sort of flies in the face of a couple of hundred years of
engineering. The lockwasher doesn't work only when loose. Pretty much,
the purpose of the lockwasher is to keep the bolt and nut threads
scrubbed together to increase the friction required for the nut to
turn. This is no different a principle than that behind prevailing
torque fasteners.
Beyond the theory, I have plenty of real-world examples to indicate that
they do work, and just fine, thank you. One of my favorites was that of
a former boss on a farm who decided, like Mr. Taylor, that lockwashers
had no real use, so he left them off the rake tines of the hay baler.
There were about forty of these on the baler, and they were simply
pieces of rod with an eye formed on the end, which slipped over a blind
bolt and were captured by a flat washer, lockwasher and nut. The tines
dragged along the ground and separated the windrowed hay into columns
which then were fed into the baler. Because of the vibration, without
the lockwashers, every tine had either loosened and was flopping around
or had fallen off in less than twenty minutes. Add lockwashers, and
everything is fine through the end of the hay season. If you want to
understand the utility of the humble lockwasher, just work on
high-vibration equipment such as farm equipment for a while.
The other bit about lockwashers comes from Volvo Heavy Equipment. They
owned 51% of a company for which I worked, and one of their
pronouncements was that, because they had decided that Loctite was a
carcinogen, only lockwashers would be used in their plants in
applications which had previously used Loctite.
It was a terrible idea, because some installations just weren't amenable
to using lockwashers (confined spaces where juggling lockwashers
inclined assemblers to leave them off, etc.), and more so because their
thinking was based on those old, old rat studies on saccharin ingestion
(saccharin is an essential ingredient of Loctite), even though one would
have to eat about two pounds of the stuff or be completely immersed in
it for a couple of weeks to receive a median lethal dose. But, the
point was that Volvo's engineers think lockwashers work as advertised. I
doubt you're going to find many mechanical engineers who would say that
they do not. Some may have preferences for PT nuts, but, that doesn't
negate the principle behind the lockwasher.
Cheers.
--
Michael Porter
Roswell, NM
Never let anyone drive you crazy when you know it's within walking distance....
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