[SML] Chain Motor Help...

[Will Leonard]

Guys,

I have a show coming up where a designer where a designer would like us to use variable speed Chain Hoists to raise a lower a platform with 2 actors riding it. We are trying to negotiate the trick, but we are getting some push back when we said we needed a minimum of a 7:1 Safety Design Factor for this move. This means that the weight of the unit is such that we would need 11 1 Ton Hoists to raise & lower the unit, when we only have access to 4. The designer emailed us a link to CM's website that states that they use a 10:1 Safety Design Factor, so that should cover the move. 

I have always taken the rating of a motor (or hardware) & then applied my own safety factor to the already lower number. (i.e.: I'm not going to put 5 tons on a 1 ton motor just because it has a 10:1 safety factor.) So am I wrong in this? Are we just being whiney? Our designer is going to be here in a few hours to meet, so what do y'all think? Bill... Delbert... Bill... Dave... Steve... anyone?

Hope y'all have beer & BBQ if you're into that thing this weekend!

Thanks,
- Will Leonard
Associate Technical Director
Alley Theatre
O: 713-315-5449
C: 713-252-9809