In Stage Rigging
mule blocks are a special designation for any sheave
which changes the direction of the cable which it is guiding. They can be found in two places in most counterweight fly systems
. The first set guides the cables from the arbor
to the grid
. The second guides them back down from the grid to the batten
Mule blocks are a major source of friction in the counterweight fly system. A mule block which is too tight creates excessive strain on the entire system and can lead to cable failure. Too loose and the cable can jump track bringing both the batten and the arbor to a sudden stop. Either can be very deadly on stage.
Part of the Stage Rigging Metanode