[CAUT] Differential chain hoist - with photo 1 (was Getting the plate out)

[Fred Sturm]

On Apr 28, 2007, at 9:22 PM, McNeilTom at aol.com wrote:

> Ah, the differential chain hoist.  Let me give you a description  
> and a couple photos.  There is a single continuous length of  
> endless chain (not the separate operating chain and lift chain of  
> the common geared chain hoist).  This chain runs over two wheels on  
> the upper fixed pulley, and one on the lower pulley, thus forming  
> two loops.  One of the loops is the 'load loop' (containing the  
> lower pulley) and the other is the 'operating loop' (no lower pulley).

	I have what Tom describes as the "common geared chain hoist." Got it  
from Grainger, and it is still available (keywords manual chain hoist  
will get you there). I find it quite adequate for the job of pulling  
plates. I used mine for a Mason CC once, and it would lift the whole  
piano with ease. (I used a rope block and tackle for the tail to get  
good balance, but on the initial pull, with friction somewhere  
keeping the plate attached to the rim, the whole piano went up). I  
find this rig quite easy and controllable. I can pull the chain with  
one hand, and guide the plate with the other. Very slow, very  
controlled, and fast enough when you want to be.
Regards,
Fred Sturm
University of New Mexico
fssturm at unm.edu



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