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(1) First shutter curtain (fig. 1-5). The shutter release knob, when depressed,pushes a release rod against a flat spring. A projection on the flat spring rides against the beveled edge of arresting lever A , which is spring loaded, and rotates it slightly. The arresting lever sear disengages a bar on the under side of main shutter roller assembly. The shaft of the main shutter roller assembly rotates, and the first shutter curtain runs off. Simultaneously, the second curtain roller of the main shutter roller assembly rotates through a small arc. It is then arrested by arresting lever B which engages a catch on the second curtain roller.

Figure 1-6 Controls in B Position, Shutter Released.

(a) B-setting (fig. 1-5, 1-6,1-7). When the shutter speed dial is set at B , the speed cam positions the adjusting lever and permits arresting lever B to move forward against a stop (fig. 1-5). Depressing the shutter release knob moves the arresting lever down and it engages the second curtain roller catch (fig. 1-7). This prevents run-off of the second curtain. Removing pressure from the shutter release knob returns arresting lever B to its upper position, disengaging the catch and permitting; rotation of the second curtain roller (fig. 1-6).

Figure 1-7. Shutter Release, Cross-Section.

(b) 1 to 1/30-second setting. The release of the second curtain, at shutter speeds between 1-second and l/30-second, is governed by the slow-speed escapement (fig. 1-3). Setting the shutter speed knob rotates the setting cam and pivots the escapement. When set for 1-second the sear of the segment gear engages the segment gear catch of the second curtain roller to its fullest extent. At faster speeds the escapement is pivoted further from the cam axis. A lesser area of the sear engages the catch, and the second curtain is released earlier. Release of the second curtain roller is delayed by the inertia of a gear train and anchor in the slow-speed escapement. With the sear disengaged, the gear train is reset by a hair spring in the escapement.

(c) 1/50 to I/1000-second setting.

Figure 1-8. Controls in 1 /1000-Second Position, Shutter Wound.

At shutter speeds of 1/50-second and faster, the slow-speed escapement is disengaged by the setting cam (fig. 1-8). When the shutter release knob is depressed, the dropping flank (fig. 1-3) rotates and presses the wedge segment of the adjusting lever against the arresting lever eccentric. Arresting lever B , (fig. 1-5) is pushed back and releases the catch of the second curtain roller (fig. 1-7).

(d) Position for rewinding (fig. 1-3). A pin on top of the second shutter curtain roller rotates when the second curtain is released. Near completion of its run it strikes the opposite end of the lower portion of the double stop lever. This disengages the double stop lever from the notch, on the under side of the driveshaft gear, and releases the stop disc. The shutter can now be rewound.




Figure 1-9. Delayed Action Lever and Release. 1-6

d. Delayed Action Release (fig. 1-9).


Delayed shutter release is accomplished by a clockwork mechanism which is spring driven. The spring is wound by a lever on the front of the camera, and the release is activated by depressing a release button.

(1) The wound spring is held under tension by a snap spring. When this is depressed, by the release button, the spring unwinds, activating a gear train and anchor. The winding gear rotates and a cam, on its shaft, moves a rocker arm. The lower part of the arm depresses the flat spring of the shutter mechanism and releases the shutter.

(2) The extent of the delay is governed by the degree to which the spring is wound.

e. Brake Assembly (fig. 37). The brake is deactivated when the shutter is wound. When the shutter is released the first curtain traverses the film aperture and, near the end of its run, activates the brake.

(1) First curtain braking. A bar, on the underside of the main shutter roller assembly gear, strikes the lower actuating plate (16) of the brake assembly. This pushes the plate forward and rotates the eccentric brake disc (15) through a small arc pressing it against the brake shoe (3). This gradually slows down the curtain and brings it to a stop.

(2) Second curtain braking. Near the end of its run, a pin on the underside of the second shutter curtain roller, strikes the upper actuating plate (12) of the brake assembly and pushes it forward. Friction washers apply partial braking at this point. As the curtain continues its travel the actuating plate (12) is pushed further forward. A notch in the plate engages an upright of the lower actuating plate (16) moving it further forward, and applies additional pressure to the brake disc and shoe.

(3) Deactivation of brake. When the shutter is being wound, a cam on the underside of the main shutter roller assembly is rotating. The cam rides against the lower actuating plate (16) and pushes it, with the upper plate, back to the deactivated position.

1-3. Film Transport

a. Film Advance and Take-up (fig. 1-2).

(1) The teeth of the sprocket wheel engage the film perforations and advance the film one frame (8 perforations) for each complete stroke of the winding lever. The driveshaft gear meshes with gear D of the take-up spool assembly. Operating the winding lever rotates the take-up spool assembly counter-clockwise and winds the advanced film onto the take-up spool.

(2) The lower end of the double stop lever, (fig. 1-3) stops the drive shaft gear. The upper end of the double stop lever is resting against the stop disc on top of the sprocket wheel assembly and prevents over-advancement of the film. The spring-loaded stop lever, which is on the same axis as the double stop lever, rests against the stop arm and prevents backlash of the sprocket wheel.

(3) The degree of rotation of the take-up spool is dependent on the diameter of the spooled film. As the diameter increases, the take-up spool must rotate to a lesser degree. This is accomplished by a compensating friction clutch (fig. 1-2).