Operation of the Angle of Site and Elevating Mechanism. The angle of site mechanism is operated by turning handwheel, the movement of which is transmitted through the shafts and gears to the angle of site worm meshing with the rocker. Movement of the rocker is transmitted directly through the elevating worm, elevating arc, and spring cylinder to the gun, and through the rocker arms to the elevating mechanism, gun, cradle, and sights. The elevating mechanism moves only gun and cradle through movement of handwheel shafts, and the elevating worm inside the rocker, which meshes with the elevating arc.
The angle of site scale is graduated in mils from 170 to 500. The range scale is graduated in meters. The zero setting of the gun is with O on the range scale opposite 300 on the angle of site scale and the level bubble on the rocker arm, right, at the center of the tube. This allows the maximum depression of 7 degrees (about 130 mils) or the maximum elevation of 11° of angle of site mechanism to be read on the angle of site scale against the zero of the range scale.
The sight, model of 1916, which acts as a support for the panoramic or peep sight, is attached to the rocker arm, left.
75 MM. GUN CARRIAGE, MODEL OF 1916.
TRAVERSING MECHANISM.
In direct fire, the axle of the bore is brought on the line of site by operating the angle of site handwheel until the cross hairs of the sight are on the target and the range is laid off independently by bringing the desired range graduation opposite 300 on the angle of site scale. Line of site may be set independent of the range, as there are two angle of site handwheels.
Traversing Mechanism. The total traverse of the gun on the carriage is 800 mils. The traversing handwheel is located on the left side of the carriage and turns in a clockwise direction for left traverse.
The traversing handwheel shaft is mounted in the angle of site bracket, left, and the angle of site bracket cover, left. A bevel pinion on upper end of the shaft meshes with bevel gear on traversing shaft, which bears in angle of site bracket, cover, left and intermediate shaft bearing bolted to top carriage. A bevel pinion at lower end of the intermediate shaft meshes with bevel gear on end of traversing-worm shaft, which is mounted in bearing in top carriage. Traversing worm meshes with traversing rack which is screwed to pintle bearing. Traversing stops are filister head screws between end teeth of traversing racks to limit movement of worm in rack.
The movement of handwheel is transmitted through shafts and bevel gears to worm and rack. Rack is mounted in pintle bearing, which remains stationary, and top carriage moves about its bearing in center of pintle bearing and bronze-lined slides around the outside of pintle bearing. Traversing scale is screwed to pintle bearing above rack, and pointer is formed on traversing worm-shaft bearing.