[NHCOLL-L:4459] Re: Drifting compactor carriages

[Patrick Boylan]

Dear Janet,

A few years ago there was a half-million GB pounds lawsuit in the English
High Court over something similar in relation to a recently built new
Record Office two storey storage block.  Investigations revealed that the
weight of the compactor units was causing the steel and concrete upper
floor to flex downwards by a couple of centimetres in the middle of the
floor.  This movement was well within normal design and safety limits in
terms of the national building construction standards, but of course it
was a potentially serious safety problem in the very special
circumstances.

Among the evidence presented was the fact that one leading specialist in
the field (at least in Europe), Bruynzeel, anticipates such changes and
includes in its design a simple height adjustment system within the roller
system's tracks, but the manufacturer of the system installed in the
Record Office did not have such an adjustment - hence the problem.

In your case it would be well worth finding if the floor bearing the
shelving is similarly distorting for some reason (slight subsidence could
possible produce a similar effect even on a ground floor concrete slab).
It would also be worth checking to see if the floor track height can be
adjusted differentially along its length.




Patrick


=====================

(Prof.) Patrick J. Boylan
(Professor Emeritus, City University London)

HOME:
2a Compass Road
Scraptoft Lane
Leicester LE5 2HF
UK

Tel.: (+44) (0)-116.220.5496

E-mail: P.Boylan at city.ac.uk
Web site: http://www.city.ac.uk/cpm/staff/pboylan.html

====================



On Thu, 20 Aug 2009, Janet Waddington wrote:

> Has anyone had an experience with compactor carriages drifting back into the open aisle?  We have several old (1980s) SpaceSaver installations with AC motors.  In the heavily loaded paleo collection a couple of carriages have been drifting back for a couple of years now - sometimes as much as a foot before they come to rest.  A couple of carriages in the mammal collections have started doing this recently. There is no electronic damping of the movement. The carriages just stop when you stop pushing the button or when the limit switch cuts out the motor.  These carriages are now stopping normally, then drifitng back. This could be a potential safety issue as there is no safety sweep in this mode.
>
> I'd be interested in knowing whether anyone else has experienced this and if you have any idea of the cause and solution. Right now we are just using a piece of wood to block the drift.
>
> Thanks,
>
> Janet Waddington
> Assistant Curator and Collection Manager
> Department of Natural History - Palaeobiology
> Royal Ontario Museum
> 100 Queen's Park
> Toronto, ON
> Canada M5S 2C6
> Phone  (416) 586-5593  Fax  (416) 586-5553
> Email  janetw at rom.on.ca
>
>