lifting sling 



rigid cage rib 



cage ring bolted 

 onto the cage ribs 



sliding fit between pin and 

 opening in cage ring 



rubber gasket 



ring with guide pins 

 bolted onto the hatch ring 



acrylic plastic hull 



lifting slings 



in the capsule. Since a rigid 

 attachment to the cage at both 

 top and bottom steel inserts was 

 undesirable, as it would restrain 

 the sphere radially during pres- 

 sure application, a special joint 

 was devised that permitted the 

 sphere to change its radial dimen- 

 sion but at the same time resisted 

 lateral forces applied to the sphere 

 by waves on the ocean surface, or 

 currents when submerged. The 

 joint devised for this application 

 consisted basically of pins attached 

 to the polar metal plates that fitted 

 into oversize holes in the cage 

 framework. Thus, the sphere was 

 permitted to change its diametri- 

 cal dimension while at the same 

 time the pin and hole joint 

 restrained the whole capsule from 

 lateral or vertical displacement 

 that would cause it to strike the 

 ribs of the cage. The sliding pin 

 joint imposes only lateral and ver- 

 tical but not diametral restraint. 

 Because of this, no external tensile 

 loading can act on the capsule, 

 regardless whether the NEMO 

 system is being lifted out of water 

 or just floating on the ocean sur- 

 face. The drawback of this capsule 

 attachment to the NEMO service 

 module was that the cage did 

 reduce to some extent the pan- 

 oramic visibility of which an 

 acrylic plastic capsule is capable. 

 Because of it, this attachment arrangement would not be as satisfactory from 

 the optical viewpoint as the tie-rod attachment. There was, however, a 

 compensating feature to the cage. If the cage members were spaced appro- 

 priately the cage could act as a protector against impacting the ship during 

 launching operations. This protective feature of the cage was felt to 

 compensate adequately for the loss of visibility caused by the cage. 



Figure 8. Rigid cage restraint concept 

 for attaching the acrylic 

 plastic capsule to the NEMO 

 service module. 



18 



