Traversing Mechanism

A slow-motion mil clicking traversing gear is provided. With the traversing gear clamp screwed up so that the teeth of the traversing gear are engaged, the traversing handle when rotated in a clockwise direction traverses gun to left, and when rotated in an anti-clockwise direction traverses gun to right. Each click represents i mil traverse.

With the traversing gear clamp unscrewed so that the traversing gear teeth are disengaged, the gun is free to be traversed by hand.

Small angles of traverse can be read off from the small dial on the traversing hand wheel. Zero setting can be established by loosening dial lock nut and tightening at desired setting.

Larger alterations in angles of traverse than that provided by the slow-motion traversing wheel may be accomplished by loosening traversing clamp and traversing gun by hand. Angles of traverse may be read off from traversing dial which is provided with an adjustable zero setting that can be turned by hand.

73 Graduated leaf,

74 Adjustable backsight slide.

75 Adjustable backsight slide catch.

76 Fixed open backsight.

77 Adjustable open backsight.

78 Six-hole adjustable aperture eye-piece,

79 Windage adjustment screw.

80 Elevating fine adjustment screw.





A blade foresight is fined at the top of end cap of water jacket, being dovetailed into the sight block, and is thereby adjustable laterally. It is provided with a tubular foresight protector.


In Plate 12 is illustrated the backsight described in detail below. It is to be noted that guns may be fitted with different types of backsights to the one described. The description that follows should enable other types of backsights to be easily understood and used. It consists of a leaf. In its lowered position an open U backsight is in position, which is sighted for 500 metres. When leaf is raised graduations on the leaf are used by which the slide is set to the range required. For large variations in elevation the catch on the right side of the slide is depressed and the slide raised or lowered to range selected. For small and fine adjustments of elevation the elevating notched wheel at the top of the slide is used. The slide carries an adjustable plate containing five different sized apertures so as to enable the gunner to select the one most suitable to the shooting conditions.

To set for the aperture required, push in with the tip of a finger on the serrated circle on the aperture plate and turn until the aperture required is at the bottom. Make sure aperture plate is corrccrly fixed by seeing that the corresponding notch on the periphery of the sight plate is engaged with the key at the top of the slide.

The aperture is set to the range marked on the leaf that coincides with the bottom face of the window (e.g., illustration shows aperture sight set for 1,500 metres). In addition to the aperture there is an open U backsight at the top of the slide. This open sight is set to the range marked on the leaf that coincides with the top edges of the shoulders of this sight (e.g., illustration shows open adjustable backsight set for 1,950 metres). It will be noticed from the illustration that the grooves in the leaf in which the slide moves up and down incline to the left, so that as the slide is raised the aperture is automatically moved to the left. This movement is made to counteract the drift of the bullet.

The leaf sight is mounted on a base which is adjustable for windage ; this adjustment is accomplished by means of the milled-headed screw situated to the left of the sight base. This windage adjustment screw, when rotated backwards towards gunner, moves sight to left to counteract for wind blowing from left to right, and when rotated forward (i.e., away from gunner) the sight is moved to the right to counteract wind blowing from the right.

plate [3 The Firing Position (Gun mounted on 1918 Tripod)

before firing


(r) Ammunition loaded into belts.

(2) Ammunition boxes.

(3) Water condenser filled with water.

(4) Combination tool, (j) Cleaning rod.

(6) Separated case extractor.

note : 4, 5, 6 and 7 are essential for possible stoppages,

(a) All mechanism must be clean, free from dust, dirt and fluff, and thoroughly oiled.

(b) "When assembled, rear barrel packing should provide a smooth watertight fit in trunnion block; copious oiling or greasing remedies slight water leak here.

(c) Muzzle gland should provide a smooth water-tight fit with barrel. The barrel should be well oiled or greased where it slides through muzzle gland.

(d) Test head space adjustment. (e) Fill waterjacket.

note : Correct carrying out of (b) and (c) should be tested by operating mechanism with bolt handle. The mechanism should work smoothly ; no undue force should be required to withdraw barrel and mechanism to the rear, and with the bolt handle released from its rearmost position mechanism should return to its fully forward position and the bolt should lock properly home against base of cartridge in chamber.

(f) Attach steam hose to steam vent in water jacket, with its tree end inserted into water condenser.

(g) Check ammunition belts ; they should be clean, dry and uniformly and correctly loaded.

(h) Tripod must be firmly seated on ground, spade feet of legs stamped in, all jamming handles tight.

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