It shouldn't require much leaning out other than to grab the
line. One should be able to operate the lines without leaning out. Pulling up on the front
line causes a slack
line above the operator as the
tension block moves up and releases all the tension it is holding. In a balanced
system, this shouldn't pose a great risk, but it isn't ideal. On completion of travel the
tension block has to
settle back down, which can cause position shifts or other unwanted motion in the
system.
Speaking of lots of weight and inertia, you might consider adding a sentence or two about the fact that in a single
purchase system, when you move a balanced
lineset you are actually moving double the weight of the scenery. This seems to be something that people gloss over a lot. If your lighting gear weighs 1000lbs, you are moving at least 2000lbs (more when you include the weight of the
batten and hardware). Also, and maybe for future video, you might mention that a well balanced
lineset is balanced at the center of travel, and usually slightly
batten heavy at lowest
trim and slightly
arbor heavy at highest
trim due to the fact that all the lift lines are on one side or the other (
wire rope is heavy).
@icewolf08 &
@StradivariusBone Alex; In full agreement and these are both points I mentioned to Strad' in my initial P.M. where I also agreed these were (Quoting Strad') "outside the scope of this (preliminary) video."
Your
point about aircraft cable being heavy clearly is always a factor in
play but becomes more and more of a factor as
system sizes grow. The first single
purchase system I worked with had a mixture of 50' & 70' pipes supported by 5 & 7 lines each. The differential weight was definitely more of a factor with the longer pipes.
The same considerations come into
play as
proscenium and
grid heights increase.
With higher prosc's come taller legs and drops / set pieces thus
grid heights increase to permit flown
goods to
clear sightlines.
Just when you become comfortable dealing with the feel of the shifting weight factor in a facility with an 85'
grid, you learn the lessons anew when you're working with grids in excess of 100'. We've a 108' and a 120'
grid in nearby cities and the experience of pulling an empty pipe in from the its highest to lowest extremes of travel can become an interesting experience with the operator needing to really lean into the operating
line to haul the
batten in initially then passing through the 'easy pulling
point' and finally having to hold the
batten back as it gains both weight and momentum wanting to run in on its own. Alex, I understand you're already well familiar with the concept but it may not be something coming appreciably into
play in Strad's
venue.
And then you make the jump to a double
purchase system and the cable lengths and weights, along with the additional weight on the arbors, drives the concept of how much weight you're shifting, putting into motion and stopping home all over again.
Next comes a genuine need for compensating chain.
In the entirety of Canada, we only have one serious installation of compensating chain. In Toronto, the "Four Seasons Center" is the home of both the National Ballet of Canada and the Canadian Opera Company. Their
grid for access and the support of spot lines is at 120' AFF (Above Finished Floor) with the
system pipes supported by overhead sheaves underhung from overhead supporting structure. It's a single
purchase facility with the lower idlers approximately 12' below
deck primarily due to the entire building's low noise concerns. Servo driven assist drives are also accommodated in their first basement
level. Every
line set is fitted with a double-width compensating chain similar to what I'm told would be employed on a very powerful motorcycle. The compensating chain installation is done right in every way with the whole
system being a smooth, quiet, pleasure to operate. Granted you've still got the joys of overcoming inertia [both at rest and in motion] to deal with but the first time you haul a pipe from upper EOT [End Of Travel] to lower EOT is a uniquely joyful experience.
With apologies for boringly droning on.
Toodleoo!
Ron Hebbard.