Engineering Note 048
April 7, 1994
Source Four Drop Test Results
ETC conducted a series of informal drop tests was to determine the durability of the components in the Source Four fixture. Three levels of drop tests were performed.
In the first level of tests (Grade 1) we stood a fixture on its nose and tipped it over. This was intended to approximate the normal rough use to which a theatrical lighting fixture may be subjected in normal operations.
In the second level of testing (Grade 2), we dropped the fixture from a height of three feet onto its nose, side and lamp housing. This test simulated very rough usage, similar to falling off a truck bed or an equipment cart.
In the third and final level (Grade 3), we rolled the fixture on its side (barrel roll) and then end-over-end down a thirty foot, 25-step set of wooden stairs. The pitch of the stairs was approximately 35°. This test simulated extremely rough handling. A fixture would normally not be subjected to this kind of abuse.
With the exception of the lamp, the fixture was still fully functional after the testing. Neither the lens, nor the reflector showed any sign of damage whatsoever. This was very gratifying given the severity of the stairway test. Some minor cracks in the castings were observed after the stairway tests, but they did not affect the rotation of the barrel. We do not believe that the cracks affected the overall structural integrity of the fixture. The bending of the shutter blades was expected, but they did not break. In the field, they could have easily been bent back into shape by hand. The damage to the lamp alignment knob was not sufficient to prevent focus adjustment and the knob is easily replaced in the field. The damage to the internal pattern holder guide was not sufficient to have interfered with the use of a pattern holder. The worst damage was sustained by the lens tube accessory holders. They were so badly crushed that we could not install a colorframe. However, we had little difficulty bending them back into shape. In any case, the lens tube castings (one or both sides) can be replaced easily in the field.