Parts Load Descriptions
The effects of two different types of loads are of concern
regarding the structure known as the Suspendulum®. Dead loads verses
live loads. Dead loads (static loads) are considered permanent loads
and vary
only with regard to the weight of the individual aerialist or swing
vehicle occupant. Live loads such as dynamic weight changes from performing “drops” change
the value of forces applied to the structure.
The Suspendulum® is a tetrahedron. The loads bearing down on each of the legs
is in direct proportion to the weight applied to the leg closest to the weight
being applied; i.e. when the load is aligned with any of the legs that leg
bears the load. When the load is aligned halfway between the supporting legs
both legs share bearing the load.
Each leg is composed of steel tubing that has a compression rate failure
above 40,000 lbs. In order to swage the ends of the tubing 40,000 lbs. of
pressure
must be applied in order to squeeze the tubing into a swaged form in order
to make one end of the tube fit into any other non-swaged end. The four inch
swage insures against bending of the tubing. Leg tubing are inserted into
4 inch swage with spring-button to assure depth of fit into adjoining tubing.
The quarter inch thick mounting plate holding the legs in place at the apex
(top) is rated at 36,000 psi made from hold rolled A36 Carbon steel.
Swing bolts attaching the steel tubing to the mounting plate are made from
hot-forged steel.
The u-bolt with which the user attaches various vehicles to is made
from forged metal bases meeting or exceeding all requirements of
ASME B30.26 including identification,
ductility, design factor, proof load and temperature requirements. Importantly,
the u-bolt used for the apex of the Suspendulum® meets other critical performance
requirements including fatigue life, impact properties and material traceability,
not addressed by ASME B30.26 and meets the performance requirements of Federal
Specification FF-C-450 TYPE 1 CLASS 1
The O-ring attached to the u-bolt at the apex has
the following criteria:
Uses for Military/Parachute
1298-1 11-1-599
Cargo/Fall Arrest/Safety
1298-1S Hot Forged Alloy Steel
Thermal Treated
Cadmium, Zinc Plated
100% Proof Load Tested @ 15.3 KN (3,600 lbs)
Meets or exceeds PIA-H-7195
Meets or exceeds ANSI Z-359.2
The cables used to keep the legs from splaying outward
and hold the tetrahedron shape in place have a 3/16” x 7/19 strand
format normally used for aircraft cabling and has a breaking strength
of 1920 lbs. The quick-link holding the cable to each foot assembly has
a working load limit of 1900 lbs.