■ range of ship periods 



maximum allowable force/X ratio 

 10% of line tension 



1.6 2.0 



oj (rad/sec) 



Period (sec) 



Figure 11. Force-to-amplitude ratio for 6,000-foot length of wire cable with 40,000-pound 

 load, showing effect of accumulator size. 



feedback system, also shown in Figure 18, is 

 incorporated to improve the performance of the 

 automatic-centering system by adjusting the position 

 of the cam that operates the boom-position sensor 

 (valve 65 ) as a function of boom-tip speed. 



Traction Unit 



The traction winch, shown in Figure 14, is of 

 the conventional double-drum, inclined-axis type, 

 using six wraps of line around the drums. Drum liners 

 are interchangeable to allow the use of different types 

 and sizes of line. The drive is by a low-torque, high- 

 speed, hydraulic motor through a reduction gear box 

 and then through a single pinion gear that drives the 



bull gears on both drums. Designed maximum speed 

 of the line is 60 ft/min at a maximum line pull of 

 65,000 pounds. The hydraulic circuitry is arranged so 

 that the winch motor can be used as a pump, the 

 main pump as a motor, and the diesel engine with its 

 Jacobs compression brake as an energy-absorbing 

 device (air compressor) to provide controllable 

 dynamic braking during lowering operations. A 

 spring-set, hydraulically released brake designed to 

 stop a runaway load is also incorporated into the 

 unit. 



Power Unit 



The diesel-hydraulic power unit is driven by a 

 743-cubic-inch-displacement, turbocharged Cummins 



10 



