The invention relates generally to cargo tie-down systems. More specifically, the invention concerns a self-energized tie-down anchor assembly for use in aircraft cargo tie-down systems.
In the past, anchor assemblies have been used in combination with longitudinally extending track members to secure various types of cargo in position with respect to a transporting vehicle. In some such anchors, a pin or other suitable projection is engaged in a corresponding recess of the track to longitudinally position the anchor. Vertical loads imparted to the anchor by tie-down straps are typically resisted by a pair of laterally rigid fingers carried by the anchor and underlying a rail portion of the track. The fingers to not assist longitudinal positioning of the anchor.
Other known anchor assemblies employ specially designed track members having periodic interruptions to facilitate anchor positioning. These anchors are longitudinally restrained with respect to the track by frictional engagement of anchor fingers with upper and lower horizontally extending surfaces of the track rail. The anchor fingers cooperate with the track rail to resist vertical loads induced by tie-down straps. Again, increased vertical loads do not augment resistance to longitudinal movement.
In aircraft cargo stowage applications, it is particularly desirable to provide a back-up system resisting longitudinal movement of the anchor since shifting cargo may induce random pitching or rolling moments that could lead to loss of aircraft control. Moreover, during landing and takeoff, large acceleration forces are incurred which may induce cargo shifting with the consequent possibility of damage. Accordingly, known positioning projections and track rail engaging devices are inadequate. In addition, the tendency of anchor fingers to straighten under vertical load is also highly undesirable since it may lead to cargo shifts and loss of aircraft control.
While a redundant, or back-up system is advantageous, weight, mechanical, and economic considerations preclude combinations of the known anchor assemblies. Moreover, weight considerations place a premium on the efficient structural design of any apparatus to be used on aircraft.
In view of the foregoing considerations, it will be apparent that a need still exists for an inexpensive, light, easily positioned anchor for use with standard track configurations while being tolerant of increased force loadings and tolerant of inclined force loadings.