# Simple Machines in Technical Theatre

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Simple Machines in Technical Theatre
USITT 2008 Simple Machines in Technical Theatre Levers Chip Haas – Technical Director, University of North Carolina Greensboro Drew Pritchard – Technical Direction Student, North Carolina School of the Arts USITT 2008 – Houston, Texas

There are three classes of levers: Class 1, Class 2 & Class 3.
All three classes have the same three components 1. Fulcrum (‘F’) – the pivot point 2. Load (‘L’) – some kind of weight or resistance 3. Effort (‘E’) – the force that is trying to move the load The differences lie in the location of these components Remember: ‘F’ always proceeds ‘E’, ‘L’ is the only part that moves. USITT 2008 – Houston, Texas

Class 1 Lever – ‘LFE’ Fulcrum is located between the load and the effort The longer the effort arm (D2), the less force necessary to move the load Effort Arm(D2) / Resistance Arm (D1)= Load / Effort USITT 2008 – Houston, Texas

Common Class 1 Levers USITT 2008 – Houston, Texas

Class 2 Lever – ‘FLE’ Fulcrum is located at one end and the effort is located at the other end of the lever The load is situated somewhere between those two points. The closer the load is to the fulcrum, the less force necessary to lift the load Effort Arm(D1 + D2) / Resistance Arm (D1)= Load / Effort USITT 2008 – Houston, Texas

Common Class 2 Lever USITT 2008 – Houston, Texas

Class 3 Lever – ‘FEL’ Fulcrum is located at one end and the load is located at the other end of the lever The effort is situated somewhere between those two points. This allows the load to be moved faster, however the effort must be greater than the load Effort Arm (D1) / Resistance Arm (D1 + D2)= Load / Effort USITT 2008 – Houston, Texas

Common Class 3 Levers USITT 2008 – Houston, Texas

Failed Use of a Class 1 Lever
Pop Up Door – Down Position Pop Up Door – Up Position USITT 2008 – Houston, Texas

Problems with this attempt at a lever
Effort arm is shorter than the resistance arm Made door even heavier to lift – solved using counterweights Trapdoor platform behind effort arm prevented any extra length to the effort arm Door Flat too close to end of resistance arm Couldn’t move high enough – 9” too short Angle of arm became too steep to keep raising door Couldn’t extend resistance arm, not enough room Couldn’t raise fulcrum – structural steel in the way Door wasn’t heavy enough to come back down, unable to attach lever to pull the door down. How was it solved? - Made it even simpler – eliminated the lever - had crew member raise and lower like a window - Not quite as smooth – locking mechanism was kind of jury rigged USITT 2008 – Houston, Texas

Use of a Class 2 Lever – ‘FLE’
Effort Load Fulcrum/ Pivot Point Example presented is a pivoting wagon unit which is attached to a pivot point. The pivot acts as a fulcrum, the scenery and people on the unit act as the weight, and the actor moving the unit acts as the effort. When moved from the end opposite the fulcrum, it acts as a class 2 lever Effort Arm(D1 + D2) / Resistance Arm (D1)= Load / Effort USITT 2008 – Houston, Texas

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