pressure by the hydraulic system compensa- 

 tor. Changes in oil volume due to tempera- 

 ture variations are also controlled by the 

 hydraulic system compensator. Additional 

 over-pressure protection of components is 

 provided by individual assembly relief 

 valves. Each of the four assemblies contains 

 a seawater leak detector. 



Any of four interchangeable terminal de- 

 vices, or tools, may be attached to the wrist. 

 The tools permit grasping and drilling, as 

 well as cutting (e.g., cables). When not in use, 

 the tools are stored in a tool rack near the 

 manipulator shoulder. Pressure and temper- 

 ature compensation of the tools is provided 

 by integral compensators. 



Two manipulator replacement counter- 

 weights are provided for port and starboard 

 installation when the vehicle is operated 

 with either or both manipulators removed. 

 Each counterweight compensates for the 

 weight of a manipulator to maintain vehicle 

 buoyancy and trim. 



The BEAVER-type manipulator in Figure 

 10.40e was the first to include variable speed 



or rate control. It was designed and con- 

 structed at North American Rockwell for use 

 aboard BEAVER, which presently has two 

 such manipulators. With eight degrees of 

 freedom and variable rate control, the ma- 

 nipulators are capable of performing a wide 

 variety of tasks — particularly so since the 

 terminations (claws) are interchangeable in 

 situ with an underwater tool array consist- 

 ing of an impact wrench, cable cutter, stud 

 gun, centrifugal jet pump, grapple and uni- 

 versal chuck. These tools are mounted on a 

 lazy-susan type of device beneath the bow 

 and in full view of the operator. 



NEKTON'S manipulator (Fig. 10.40f) is a 

 pragmatic detour around systems analysis. It 

 consists of no more than a thru-hull steel rod 

 which can be pushed, pulled, twisted and 

 rotated through and about the penetration, 

 within a 90-degree included angle and a claw 

 which can be opened or closed by the opera- 

 tor who also provides the muscle power. The 

 arm is a 0.5-inch-diameter stainless steel 

 tube which encloses a %-inch-diameter solid 

 rod. Inboard handles, when squeezed, pull 



530 



