On Sat, 08 Jun 2019 19:32:22 +0100, Steve Walker wrote:

On 08/06/2019 17:46, Chris Hogg wrote:
On Sat, 08 Jun 2019 17:19:16 +0100, Archibald Tarquin Blenkinsopp Esq
wrote:

On Sat, 08 Jun 2019 16:52:45 +0100, Chris Hogg wrote:

On Sat, 08 Jun 2019 16:44:44 +0100, Chris Hogg
wrote:

My washing machine has just fallen apart inside accompanied by much
loud graunching noise. The drum seems to have broken away from its
bearings and is very loose, and I can hear other bits rattling
around as I push the drum round by hand. Fortunately it was into its
rinse cycles and was coming to the end of a spin, so there was only
damp rinsed washing to cope with. It's almost exactly ten years old
(bought July 2019) so I reckon it's time to replace it.
^^^^^^^^^^^ LOL! July 2009!

Is this washing machine blue with a light on top and the logo "police
telephone box" on the side?

chuckle I did correct that time warp in the follow-up. But the noise
it made as it self-destructed were not dissimilar to time warping!

https://www.ukwhitegoods.co.uk/help/...dvice/washing-
machine/3378-direct-drive-versus-indirect-drive-washing-machines

AB
Thanks for the link. I see there's precious little advantage of DD
machines cf. belt driven ones.

I can think of one possible advantage, but I don't know whether it would
actually make any difference in reality - belt drives seem to have quite
a high tension and that puts a significant and constant side load on the
drum's rear bearing.

There may be some possibility of accelerating the wear a little and many
machines seem to have bearings that are difficult or even impossible to
replace these days.

The effect could well be negligible though.


You are quite correct. In this case, as for BSA's error in replacing the
drive side crankshaft ball bearing in the Triumph Bonneville engine with
a roller bearing (presumably in the mistaken belief that it would cope
better with the resulting drive thrust bias since they let the timing
side retain the original ball race bearing), it's the out of balance high
speed rpm loading that trumps such modest sidethrust bias induced wear
(and by a very wide margin) every time.

In the case of the BSA built Bonneville engines, to compound their gross
engineering incompetence (which goes all the way back to pre-war years),
they'd not only overlooked the fact that such a high revving engine
(compared to their own efforts at making a 650cc parallel twin which had
no reserve for tuning to a similar output by virtue of poor quality
materials and inadequacies in their design by way of structural reserves
to cope with even modest performance tuning attempts) with a flexible
crankshaft only supported by the engine case bearings would require a
bearing type that would, unlike the roller bearing replacement, tolerate
this dynamic misalignment stress, namely a ballrace type.

It took a mere 14,000 miles to totally knacker the roller bearing whilst
the ballrace timing side bearing (which got changed out anyway along with
the roller bearing) was still as good as new. Unfortunately, I missed the
opportunity to correct this mistake the first time I replaced the
bearings, foolishly fitting a roller bearing on the drive side instead of
fitting ballraces both sides.

Unfortunately, by the time this happened again at the 28,000 mile mark,
I'd managed to snap both sparkplugs in my attempts to change them out and
never got the chance to put the bike back on the road. Hopefully, the new
owner whom I had appraised of BSA's engineering vandalism, will see a
damn sight more than 50,000 miles of wear and tear out of a replacement
set of ballrace bearings.

As with motorbike engines, it's the high speed spin cycle that stresses
washing machine drum bearings to the limit (and beyond with some makes).
The side thrust loading pales into insignificance by comparison.

Incidentally, direct drive does offer advantages over the use of a
drum, belt driven from a universal ac/dc motor with the extra frictional
and electrical losses of carbon brush/commutator gear and the order of
magnitude faster spin speeds of an armature with windings that are
uncomfortably close to exploding out of the armature slots due to
centripetal force.

Until the profiteering exploitation of the modern brushless DC motor is
dialled back a few notches to that which currently applies with the older
ac/dc motor technology, the ROI in electricity and maintenance savings
are unlikely to be realised over the typical lifetime of a domestic
washing machine.

For now, the pragmatic choice is to stick with the tried and tested belt
drive technology until the reduced manufacturing costs of direct drive
force the manufacturers to relent in their exploitation of the BLDC
direct drive system as their latest cash cow innovation.

--
Johnny B Good

On 20/06/2019 04:13, Johnny B Good wrote:
I can think of one possible advantage, but I don't know whether it would
actually make any difference in reality - belt drives seem to have quite
a high tension and that puts a significant and constant side load on the
drum's rear bearing.

There may be some possibility of accelerating the wear a little and many
machines seem to have bearings that are difficult or even impossible to
replace these days.

The effect could well be negligible though.

You are quite correct.
Nope. Belt drives of the toothed varietyty add very little side load at all.

And all of this is dwarfed anyway by the masive sideloads that out of
balance washing imposes.




--
New Socialism consists essentially in being seen to have your heart in
the right place whilst your head is in the clouds and your hand is in
someone else's pocket.