1-2| 1 — |-" 1 range of ship periods 1— ^ \ 



1.6 2.0 



oj (rad/sec) 



Period (sec) 



Figure 10. Response ratio of nylon rope, showing effect of length. 



manner. In the automatic mode, valve 60A is in the 

 center (off) position, and valve 60B is in the auto- 

 matic position (as shown). Oil is supplied to the 

 circuit from the hydraulic source via the pressure 

 regulator 67A and the pressure-compensated flow- 

 control valve 66. With the boom tip above midpoint, 

 valve 65 supplies oil to accumulator bank 63D 

 through F while simultaneously releasing oil from 

 accumulator bank 63A through C through flow- 

 control valve 64 and back to the main reservoir. When 

 the boom position moves to below the midpoint, the 

 oil supply is shifted to 63A through C while 63D 

 through F are connected to the drain. If the average 

 boom position is at the midpoint, the pressures in the 



two accumulator banks remain equal. If, however, the 

 average boom position should move away from 

 midpoint, one accumulator bank would receive more 

 oil and, thus, have a higher pressure than the other. 

 When the required pressure difference is reached, 

 valve 61 is activated, turning on both the appropriate 

 gas-transfer valves 19A through D and the 

 compressor, to transfer gas in the direction necessary 

 to bring the average boom position back to midpoint. 

 Control-system response time is governed by both the 

 relative and absolute settings of valves 64A through 

 66, and pressure regulator 67A. For manual control, 

 valve 60A bypasses the boom-controlled valve and the 

 flow-control valves 64C and 66. A boom-velocity 



