<VV> Fwd: Precession

[Hugo Miller]

-------- Original Message --------
Subject: Precession
Date: 2020-03-06 09:38
 From: Hugo Miller <hugo at aruncoaches.co.uk>
To: <hugo at aruncoaches.co.uk>
Copy: VirtualVair <virtualvairs at corvair.org>
Reply-To: <hugo at aruncoaches.co.uk>

Footnote - that is also why wire wheels have left hand thread spinners, 
but this time they go on the RIGHT, not the left. The hub will tend to 
'walk' around the inside of the wheel as it rotates - imagine a very 
loose-fitting wheel on a hub & you might see what I mean.

On 2020-03-06 09:30, Hugo Miller wrote:
> Was it a stock wheel? Left-side wheel nuts (lug nuts) should be
> left-hand thread, and on quality cars in the UK (Rolls Royce, 
> Bristol)
> they were at one time. This is to counter the effects of precession,
> which is too complicated to explain in a short e-mail, but it is the
> reason the left pedal on a bicycle will have a left-hand thread
> holding the pedal on, which seems counter-intuitive, as the rotation
> of the pedal around the shaft will tend to unscrew it. But the forces
> of precession act in the opposite direction, and they are reckoned to
> be stronger. Basically, if you imagine the pedal being very loose on 
> a
> plain shaft with no bearings in it, the shaft will tend to 'walk'
> around the inside of the pedal as it rotates, and that is precession.
> There was and still is a debate in the UK about what the government
> calls "Wheel-loss syndrome" on coaches. Typically of governments
> everywhere, instead of fixing the problem, they call it a 'syndrome'.
> Basically, the story is this; traditionally, all British-built
> commercial vehicles used conical wheel nuts (like a car) to locate 
> the
> wheels, and more importantly, they used left-hnad threads on the
> left-side nuts. So far so good. But then we adopted the European
> system of spigot-fixed wheels, using flat-faced nuts and, more
> importantly, they used right-hand threads all round. And the left 
> rear
> (twin) wheels immediately began falling off all over the place. The
> government even launched a competition to find a way to keep the
> wheels on. Idiots! All they have to do is use left-hand threads and
> the problem goes away. I did try to explain about precession to the
> relevant govt dept, but I don't think they understood it. Anyway, our
> left rear wheels are still falling off, only now it's not an
> engineering problem but a syndrome.
>
>
> On 2020-03-06 08:58, Byron LaMotte wrote:
>> Yikes, I thought it was just me. I lost a LR wheel at 60 mph.
>> Fortunately there was a grassy area to the left to move over to for 
>> a
>> soft landing. 
>>