into a primer. Table I lists some of the physicsul characteristics 

 of this driver and other tools discussed in this paper. The Driver 

 Mk 22 cannot be reloaded and is discarded once used. The ssime 

 propellant and stud weights are used for each target. This driver 

 is in production and in the Fleet. 



SALVAGE DRIVER (LIGHT-DUTY) . This driver is shovm in Figure 2. 

 It is 17 inches long and is used for fastening underwater patch 

 plates over holes in ship hulls during salvage operations. The 

 driver breaks open at the breech to accept an actuator (or car- 

 tridge) which may be inserted under water. Unlike the Driver Mk 

 22, this driver may be fired repeatedly. However, the barrel of 

 the driver is open to water and, as a resvilt, the kinetic energy 

 of the stud, and xmderwater operating depth, are limited (see 

 Table l). Because of variations in the hardness and thickness of 

 ships' plate, there also are variations in propellant and stud 

 weights in actuators for this driver. On the working site, the 

 diver selects actuators which match the plate being patched. A 

 heavy stud, driven by a heavy propellant load, will go right 

 through thin plating. Figures in Table I show the largest of 

 the available propellant and stud weights for this driver. The 

 Light-Duty Driver originally was designed by the Mine Safety 

 Appliances Co. of Pittsburgh, Pa., and in this form has been in 

 the Fleet since World War II. Because of the age of the drivers 

 in the Fleet and the addition of tighter specifications on navy 

 gun-type mechanisms, these drivers all were reworked during I968. 

 Then, a development program for a replacement driver was under- 

 taken Eind is planned for completion in April 1970. 



SALVAGE DRIVER (HEAVY-DUTY) . Figure 3 shows the Heavy-Duty 

 Driver being used diiring a test shot. This driver is 20 inches 

 long and has much greater penetrating power and operational depth 

 characteristics than the Light-Duty Driver. The increased power 

 comes from having a sealed barrel and heavier propellant and stud 

 weights (see Table I). As is the case for the Light-Duty Driver, 

 this driver has a variety of propellant and stud weights available. 

 Table I shows the heaviest of these. The Heavy-Duty Driver has a 

 greater operating depth than the Light-Duty Driver due to the 

 sealed bairrel. The diver carries the basic driver mechanism and 

 loaded sealed barrels to the landerwater work site. After each 

 shot, the expended ban?el is replaced by a loaded barrel. Expended 

 barrels are reloaded with propellaint and a new stud and eire re- 

 sealed in a surface support area. In addition to normal stud 

 driving, this driver has the capability to punch a hole in ships' 

 plate using an especially configured 5/8-inch diameter ram in 

 place of the normal bullet-shaped stud. The Heavy-Duty Driver 

 also is a product of the Mine Safety Appliances Co. A program 

 of rework and redesign has been undertaken similar to that for 

 the Light-Duty Driver. This work is scheduled for completion in 

 May 1970. 



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