DETAILED DESCRIPTION 



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INCHES 



Q. Propeller shaft of &-in. diameter stainless steel, connected by 5 to Q', which is a \-'m. steel 

 drive shaft to the gear box. OA is a stainless steel collar secured to the propeller shaft by set screws 

 and situated in front of the bearing to resist the drag (Figs. 3, 4). 



R, R'. Rods, two on each side, secured to the 

 ring M behind and to the vertical fin G in front 

 at RG. These serve as guards to prevent objects 

 such as fish, seaweed, etc., being caught in and 

 jamming the propeller (see p. 468) (Figs. 3-5). 



S. Universal joint of coiled spring type con- 

 necting the propeller shaft Q and shaft Q' 

 (Figs. 3, 4). 



T. Top half of gear box. This is formed of a 

 casting extending from side to side 1 of section B, 

 having a dome-shaped swelling, carrying a screw 

 plug TB in its centre, covering the gearing and 

 having at the rear the housing for the bearing of 

 the shaft Q'. Incorporated with this bearing is 

 an adjustable packing gland with a locking device 

 TA (Figs. 3-5, 7). 



U. Bottom half of gear-box casting carrying 

 the gears and bearing for drive worm VE (Fig. 7). 



V. Reduction gearing (see Fig. 7). VA is the 

 primary driving worm secured to shaft Q' carried 

 in bearings in the top half of gear box and having 

 between it and the rear bearing a thrust ball race. 

 VB is the primary gear wheel which is driven by 

 VA and secured to a shaft carried in the bottom Fi S- 6 - The P r0 P elIer removed from shaft ' 



half of the gear box. Also secured to this shaft is the secondary worm VC driving the secondary 

 gear wheel VD. This gear wheel VD is secured to a short vertical shaft which passes through the 

 bottom of the gear box, in which is formed its bearing, and having secured to its outer end the 

 worm VE which drives the gear train in the internal mechanism. 



W. Nose-piece castings which may be fitted into the front of the water tunnel to reduce the 

 opening to 1 in. square or £ in. square or any other size as desired and held by screw above (Figs. 3, 5). 



X. Shock absorber or vibration damper to take up vibrations in the towing cable, see Fig. 17 and 

 description on p. 489 (also Figs. 3, 4). 



Y, Z. Hinges of the two doors on the left-hand side of the central box section. The forward door 

 overlaps the rear door and is strengthened along its free edge by the metal strip Z. The doors are 

 kept closed by this strip engaging with spring clips ZA and ZA' attached to the top and bottom of 

 the central box section (Fig. 3). 



Spring washers of appropriate metal are fitted under nuts where necessary. 



The centre of balance, determined with the vibration damper X and nose cap W taken off, is 

 i2| in. from the front of the machine. A variation of ± jg in. may be allowed but not more. 



The internal mechanism will now be described. It is illustrated in Figs. 8-16. The 



mechanism frame is made in two sections, front and rear, hinged about the rollers m 



and n (see Figs. 14, 15), and held together by the plates/ and/' and the clamping rods 



e and e'. 



1 The casting extends over the top on the left-hand side beyond the limits of the gear box. This is to 

 give external symmetry which is of great importance in stabilizing the machine when towed at high speeds. 

 The casting was originally asymmetrical, but modified after trials. 



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