On Sat, 21 Aug 2010 14:05:57 -0400, Ecnerwal
wrote:

In article ,
Sunworshipper wrote:

I've been forgetting to ask if there are any great ways to design a
I-beam trolley for a winch. Awhile back we unloaded a machine and the
chain slipped around a cast part and jarred the whole crane
contraption I have in the shop. The light weight electric hoist
trolley that wasn't in use jumped up and pivoted right off and came
slamming down.

A properly designed and installed trolley should not be able to jump
off, even if the wheels are destroyed. However, it's all too common that
they are not installed correctly, especially if they are also adjustable
to fit multiple sizes of beam. IIRC, it was one of those (locking pins
not installed) that ended the long run of no lost time accidents at the
local paper mill at a bit over half-a-million manhours. It hurts when
one falls on your head, even if you did remember your hard-hat.

Anyway, the design should include flanges that are secured running close
enough to the web that there is no way to get the trolley off without
taking it apart, and means of securing it together that cannot become
unscrewed (cotter pins or the like on nuts and bolts). It's hopefully
obvious that the flanges need to be strong enough to support the entire
load plus considerable safety factor, as they would only come into play
if the wheels are destroyed, probably indicating an overload condition.

There's probably also a good argument for not building one yourself, as
opposed to buying one that's properly designed and then properly
installing it, overhead lifting devices being the load of liability that
they are, but I suspect you don't want to hear that. If you happen to
have a licensed mechanical engineer friend, have them sign off on the
design...and be willing to pay a few bucks for that.

Yeah yeah, I know. Hey, it will be better than what was up there.

http://hoists.apluswhs.com/hoist-tro...adius-trolley/

Wow, they are pricey, A? Well, I don't like it anymore.

I hear ya, sounds like good advice except the hiring and Engineer.

I almost got killed by one way back when. Was doing diesel cranks and
set one in one of the three machines and rolled the hoist out of the
way a bit with the chain. Then turned back to one of the other
machines for a special tool and heard chain links piling up. Ya should
have seen the dent in the machine and the floor. The boss was ****ed,
he was SCREAMING at me " That thing has been up there since 1951 and
nobody else ran it off the end before ! They didn't even drill a hole
in the end and put a bolt for a stop!

SW