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United States. Army. Ordnance Dept.

Handbook of artillery : including mobile, anti-aircraft and trench matériel online

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Weight of gun, carriage, and limber (British) fully equipped, also loaded

with shrapnel and fuze boxes pounds . . 4, 591

Weight of gun, carriage and limber (American) fully equipped, also loaded

with shrapnel and fuze boxes pounds. . 4, 458



99




100

75-MILLIMETER GUN AND CARRIAGE, MODEL OF 1917 (BRITISH.)

The gun is built up of alloy steel, consisting of a tube, a series of
layers of steel wire, jacket, and breech ring. The tube extends
from the rear end of the chamber to the muzzle. Over the rear por-
tion of the tube are wound 15 layers of steel wire. The jacket is
fitted over the exterior of the tube and wire, and is secured longitu-
dinally by corresponding shoulders and the breech ring, which is
screwed over the jacket at the rear and secured by a set screw. The
breech ring is prepared for the reception of the breech mechanism,
and is provided on the upper side with a lug for the attachment of
the hydraulic buffer. Longitudinal projections on each side of the
jacket form guides for the gun when in the cradle of the carriage.
A plane for a clinometer is prepared on the upper surface of the breech
ring. Vertical and horizontal axis lines are cut on the face of the
muzzle for use in verifying the adjustments of the sight.

The breech block is of the interrupted screw type having two threaded
and two slotted sectors. The breech recess of the gun is slotted
and threaded to correspond with the threads on the block and the
latter is screwed to a cylindrical section, or carrier, which is hinged
to the right side of the breech. Hinged to the rear face of the carrier
is a hand lever, provided with bevel teeth which engage with corre-
sponding teeth on the rear face of the breech block, so arranged that
when the lever is pulled to the right, the first movement of the lever
unlocks the breech block, and on continuing the motion the block
and carrier are swung into the loading position. The breech is
opened by the cannoneer on the right seat pulling the hand lever
toward him. The extractor, hinged to the right side of the breech,
is automatically actuated in opening the breech, thus ejecting the
empty cartridge case.

The firing mechanism is so arranged that the gun can not be fired
before the breechblock is home and the hand lever locked and is
known as a continuous-pull mechanism. By means of the firing
lever on the left side of the gun, operated by the gunner, the firing
pin which seats in an axially bored hole in the breechblock, is cocked
and fired by one continuous backward motion of the lever.

The carriage has a tubular steel trail and axle, the rear end of the
trail being fitted with a spade, lifting handles, trail eye, and traversing
lever. The top carriage is provided with bearings, by means of which
it is pivoted on the axle for traversing. Bearings are provided at
the top to receive the cradle trunnions on which the cradle pivots.
Longitudinal recesses are cut in the inner surface of the lower portion
of the cradle for the reception of the guides on the jacket of the gun.

A seat is provided on the left side of the trail for the gunner who
sets the sights and fires the gun, and one on the right for a cannoneer
who sets the range and operates the breech.



101




102

TJio ''Mi& ooTriar^ tojJ 1 fc,n*J' main shields and the apron are provided
for the protection of the personnel against gun fire.

The recoil cylinder is contained in the spring case in the upper por-
tion of the cradle and is surrounded by two sets, inner and outer, of
four sections each, of counterrecoil (running-out) springs, these
being held under initial compression between an external flange on
the front end of the recoil cylinder and an internal flange at the rear
end of the outer spring case. The cylinder is attached and secured to
the rear end of the gun by two nuts, while the piston rod with piston,
which fits inside of the cylinder, is secured to the forward "end of the
spring case. The piston rod is bored out for the reception of the
counter recoil buffer which is secured in the rear end of the cylinder.

Upon being fired the gun recoils, carrying with it the recoil cylin-
der. The oil is forced to pass from in front of the stationary piston
to the rear through grooves of graduated depth which set up an
hydraulic resistance, thus checking the energy and bringing the gun
to rest. In recoiling, the gun further compresses the two sets of
springs which, after the gun has reached its maximum recoil, cause
it to return to battery. The counter recoil buffer displaces the liquid
in the rear end of the piston rod, the liquid being forced to escape
over the tapered flats, thus resulting in the gun returning to battery
without shock.

A gravity tank is bolted to the front end of the recoil mechanism,
which insures the cylinder being constantly filled, and is protected
from gun fire by a shield.

The angle of sight level is carried on a bracket riveted to the under-
side of the rocking bar at the rear end and is adjusted by a leveling
screw to which is attached a micrometer disc for setting off the
angle of sight.

The range indicator is fitted to the right side close to the handwheel
and consists of a meter scale ring graduated on its face in hundreds
of meters, the periphery of the ring being graduated in mils. The
mechanism allows an elevation of 16 and depression of 5.

The elevating gear is divided into two portions, upper and lower,
and so arranged that the gun may be elevated or depressed without
altering the line of sight.

The traversing gear is pivoted to a bracket fastened to the trail at
the rear end of the top carriage, and is operated by a handwheel
extending out to the left side by means of which the gun may be
traversed 72 mils right or left from center. A scale strip and pointer
indicate the angle of traverse.

Wooden wheels, 56 inches in diameter, are used, having steel tires
3 inches in width. Drag washers free to rotate about the hubs are
secured by the dust cars.



103




104




105

The tire brake is for use in traveling, and is always used when firing.
Brake arms are pivoted at one end to a bracket on the trail and have
at their other end a cast-iron brake shoe which acts upon the tire of
the wheel. The braking action is adjustable and brakes are operated
by a lever having an eccentric link at its end.

The sights used are the rocking-bar sight and panoramic sight,
model of 1917, which are located on the left side of the carriage.

Fixed ammunition is used in this 75-millimeter field gun and is
made up of either common shrapnel or common steel shell. Shrap-
nel rounds are issued with the projectiles filled and fuzed; the shells
rounds are issued filled but not fuzed, and contain an adapter with
booster charge.

The projectiles average in weight; shrapnel, 16 pounds fuzed;
shell 12.3 pounds fuzed. The components of one round are the
cartridge case with primer, powder charge, projectile, and fuze in
shrapnel, and adapter and booster in shell.

75-MILLIMETER GUN MATERIEL, MODEL OF 1917 (BRITISH).

A battery of British 75-millimeter gun carriages is accompanied
by the following vehicles:

75-millimeter gun carnage limber, model of 1917, (British). 1

75-millimeter gun carriage limber, model of 1918. 1

75-millimeter gun caisson, model of 1918.

75-millimeter gun caisson limber, model of 1918.

Forge limber, model of 1902 ML

Store limber, model of 1902 MI.

Battery and store wagon, model of 1917.

Battery reel, model of 1917.

This gun was formerly 3.3 inches in caliber but was modified to
75 millimeter giving interchangeability with French ammunition.
All of this materiel used by the American Army was manufactured
in the United States. The gun carriage limber, model of 1917, is of
British design.

1 Either one of the above limbers may be issued.



75-MILLIMETER GUN CARRIAGE LIMBER, MODEL OF

1917 (BRITISH).



The standard British limber carries cartridges horizontally, but
is not arranged with compartments or diaphragms. The American
product of the British limber is superior to the standard British
vehicle in that diaphragms are included in the ammunition chests.
The limbers are, however, fitted with wooden poles, which are more
liable to breakage than steel poles; they have single draft hooks,
instead of double trees for equalizing the pull on the braces; the pintle
latch is not so effective as the American, nor the ammunition chest
doors so well suited to their purpose; and they are not adapted to
the American harness, as the distance from the neck yoke to the
draft hook is 6-inches shorter than in the American design and our
harness can not be so readilv connected to the neck voke.




FRONT VIEW OF LIMBER.

Weights, dimensions, etc.

Weight, complete, empty pounds. . 1, 016

Weight of tools and equipment carried do 114

Weight of ammunition carried do .... 516

Weight, completely equipped and loaded do . . . . 1, 646

Weight of gun, carriage and limber, completely equipped with 21 rounds of

ammunition pounds. . 4. 591

Diameter of wheels inches . . 56

Width of track do. ... 60

Turning angle with carriage degrees . . 70

The British design of gun carriage limber is constructed of a frame
consisting of two middle and two outer rails connected at the front
and center by a bar and braces and surmounted by an ammunition

chest of steel.

(106)



107



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108




fc



109

The chest opens at the rear and is fitted with perforated diaphragms
for carrying 24 rounds of fixed ammunition and a compartment in
the center holding two wooden trays for small stores.

The pole is of wood, protected at the front end by steel wrapping
plates and fitted with a neck yoke for use with breast collar harness.




REAR VIEW OF LIMBER.

The axle is a seamless steel tube fixed to the rails by flanges, and
the wheels are the same as those used on the gun carriage.

This limber is used only in connection with the 75-millimeter gun
carriage, model of 1917 (British).

The 75-millimeter gun carriage limber, model of 1918 (American)
a description of which may be found on page 110, can be used as an
alternate for this vehicle.



75-MILLIMETER GUN CARRIAGE LIMBER, MODEL

CF 1918.



The limber is of American design, and is of metal throughout,
excepting the spokes and felloes of the wheels. The frame consists
of a middle rail and two side rails. The middle rail is in the form of
a split cylinder, one-half passing below and the other half above
the axle, uniting in front to form a seat for the pole and in the rear to
form a seat for the pintle-bearing guide. An automatic pole support,
described on page 160, is provided.

The ammunition chest is a rectangular steel box, having a door at
the rear hinged at the bottom, and swinging downward to an approx-
imately horizontal position. Three perforated diaphragms within the
chest support 18 rounds of fixed ammunition and 3 tubular oil cans.

The axle is of forged steel, made in one piece. The standard 56-inch
wheels are used. See page 158.

This limber is used in connection with American, British, and
French 75-millimeter materiel.

Weights, dimensions, etc.

Weight complete, empty pounds.. 963

Weight of tools and equipment carried, oil cans filled do 134

Weight of ammunition carried (shrapnel) do 365

Weight of fuze boxes, loaded do 62

Weight, completely equipped and loaded do 1,524

Rounds of ammunition carried in limber chest . 18

Diameter of wheels inches. . 56

Width of track do 60

Free height under limber do 24

Turning angle with carriage degrees. . 78

(110)



1 1 1




REAR ViEVV OF LIMBER.




18322820 8



FRONT VIEW OF LIMBER.



112




75-MILLIMETER GUN CAISSON, MODEL OF 1918.



The caisson consists of a steel chest carried on wheels and axle by
means of a spring support. This support consists of helical springs
held by suitable axle and chest brackets at each end of the chest.
The Belleville springs absorb the shock of rebound.




FRONT VIEW OF CAISSON.

The chest carries 70 rounds of ammunition arranged in 5 horizontal
rows of 14 each. Protection from small-arms fire is provided by the
front door, rear plate, and apron, which are made of armor plate.
The chest provides seats for three cannoneers, and is equipped with
fastenings for carrying a full complement of tools. A rack is provided
at the back of the chest for carrying fuze boxes. On the front left
side of the chest is fastened the fuze setter.

The caisson is equipped with a short pole and lunette combined
with a pole prop. On the rear the standard pintle is provided.

(113)



114





gfe g^ia




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115



Standard 56-inch wheels are used and band brakes are provided.
See page 158.




GUN CAISSON AND GUN CAISSON LIMBER, LIMBERED.

Weights, dimensions, etc.

Weight complete, empty . pounds. . 1, 425

Weight of tools and equipment carried do 62

Weight of ammunition carried (shrapnel) do 1, 421

Weight of fuze boxes, loaded .do 124

Weight completely equipped and loaded do 3, 032

Weight with limber completely equipped and with 106 rounds of ammuni-
tion pounds.. 4,961

Rounds of ammunition carried 70

Diameter of wheels inches. . 56

Width of track do 60

Free height under caisson do 21

Turning angle with limber degrees. . 81



75-MILLIMETER GUN CAISSON LIMBER, MODEL OF

1918.



The gun caisson limber is practically the same as the gun carriage
limber, model of 1918, except that the chest is larger and carries
more ammunition. Each diaphragm is perforated with 39 flanged
holes, which accommodate 36 rounds of ammunition, and three
tubular oil cans.

This limber is used in connection with the American, British, and
French 75-millimeter materiel.




FRONT VIEW OF CAISSON LIMBER.

Weights, dimensions, etc.

Weight, complete, empty pounds. . 1, 003

Weight of tools and equipment carried (oil cans filled) do 134

Weight of ammunition carried (shrapnel) do 730

Weight of fuze boxes, loaded do 62

Weight, completely equipped and loaded do 1, 929

Rounds of ammunition carried in limber chest 36

Diameter of wheels inches . . 56

Width of track do 60

Free height under limber .' do 24

Turning angle with caisson degrees. . 81

(116)



117




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2



3-INCH GUN MATERIEL, MODEL OF 1902.



When the United States entered the World War there were on
hand approximately 544 3-inch field guns, model 1902, and the
necessary equipment therefor. The 3-inch, model 1902, materiel
includes gun, carriage, limber, caissons, caisson limbers, battery
wagons, forge limbers, store wagons, store limbers, combination
battery, store wagons and limbers, battery reel, also reel and carts,
as issued to the 75-millimeter materiel.

The needs of the fighting army received first attention, but a large
number of troops in the training areas and camps required materiel
for use in their preliminary instructions; thus 154 batteries of 3 -inch
model 1902, materiel were distributed for training purposes in the
United States which were considered substitutes for the 75-millimeter
materiel.

The 3-inch field gun, American model 1902-1904-1905, is equipped
with a breechblock of the interrupted-screw type. The breech
mechanism consists of a handle pivoted vertically to provide hori-
zontal movement of the handle to the right to open the breechblock.
In opening, the mechanism performs two functions: Revolves the
breechblock, releasing it from the threads, and then swings the block
open. At the same time the cartridge case is ejected from the gun.
In closing, the threaded movement firmly seats the cartridge in the
powder chamber, and the threads withstand the backward thrust
of the powder gases.

The recoil mechanism is of the hydro-spring type, with the housing
attached to the carriage, and located underneath the cannon. The
firing mechanism, in the latest design, is operated either by a lanyard
attached to the trigger, or by means of a firing handle on the cradle,
and is of the continuous-pull type. \Yhen the breechblock is
unlocked the gun can not be fired.

Weights, dimensions, and ballistics.
Weight of gun:

Models of 1902 and 1904 pounds. . 835

Model of 1905 do .... 788

Caliber - inches . . 3

Length of gun do 87. 8

Length of bore do 84

Length of rifled portion of bore do 72. 72

(118)



11!)




ViEvV Ur CARRIAGE.




REAR VIEW OF CARRIAGE.



120

Rifling:

Number of grooves 24

Width of grooves inch . . 0. 2927

Depth of grooves do 0. 03

Width of lands do 0. 01

Twist, right-hand:

Models of 1902 and 1904; 1 turn in 50 calibers at origin to 1 turn in 25 cali-
bers at 12.52 inches from muzzle, thence uniform.

Model of 1902: turn at origin to 1 turn in 25 calibers at 9.72 inches from
muzzle, thence uniform.

Weight of projectile (filled and fuzed) pounds. . 15

Weight of cartridge case do 2. 25

Weight of fixed ammunition (1 round) do .... 18. 75

Capacity of cartridge case cubic inches. . 66. 5

Muzzle velocity feet per sec . . 1, 700

Maximum pressure per square inch , pounds . . 33, 000

Range at 15 elevation yards . . 6, 000

Maximum range (approximately) do 8, 500

Weight of carriage with 4 rounds of ammunition, weighing 75 pounds. pounds. . 1, 685

Weight of gun and carriage , fully equipped do 2, 520

Weight at end of trail, carriage limbered do 115

Diameter of wheels inches . . 56

Width of track do 60

Length of recoil of gun on carriage do 45

Height of axis of gun do 40. 875

Height of line of peep sight do 44. 9

Length of peep-sight radius do 36. 75

Maximum angle of elevation degrees . . 15

Maximum angle of depression do 5

Amount of traverse of gun and carriage mils . . 140

Rounds of ammunition carried on carriage 4

3-INCH GUNS, MODELS OF 1902, 1904, AND 1905, AND CARRIAGE MODEL

OF 1902.

The guns are of three models, 1902, 1904, and 1905, and are prac-
tically the same except that the latter two models differ from the
1902 model in breech mechanism and the 1905 model is 50 pounds
lighter in weight.

The gun is built up of nickel steel and consists of a tube, the rear
portion of which is enveloped by a jacket which also projects beyond
the rear end forming a recess for the breech block. A locking hoop
is shrunk on the tube and the forward end of the jacket to secure
the latter to the tube. The front clip is a short hoop shrunk on the
tube near the forward end which guides the gun in recoil.

The breechblock on all three models is of the interrupted-screw
type, and rotates in the block carrier which is hinged to the rear
end of -the tube on the right, side. The block of the 1902 model has
two threaded and two slotted sectors and the block of the 1904 and
1905 models which have identical breech mechanisms, has four
threaded and four slotted sectors. The breechblock is operated






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(122)



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" 1




124

by a lever pivoted to a lug on the block carrier which has at its outer
end a handle and at its pivot end, a segment of a bevel gear, meshing
with a corresponding segment on the rear face of the block. On
pulling the handle to the right, the first 117 rotates the block until
the threaded sectors are disengaged. A further movement of 90
swings the block and carrier on its hinge until free of the bore.

The firing pin is eccentrically "located in a recess in the block,
when the breech is open. As the breech is closed the pin is automat-
ically moved to one side until it is in alignment with the axis of the
bore and primer of the cartridge case. This is a safety feature
which prevents the accidental discharge of a round before the breech
has been fully closed.

The carriage is known as model of 1902. A tapering box-shaped
trail is secured to brackets around the axle and has at its rear end a
spade and float. Two compartments are provided in the trail, one
for tools and one for the rear sight. A seat is riveted to each side
of the trail, one on the left for the gunner, and one on the right for
a cannoneer. In front of the compartments are two cross transoms
which form a support for the elevating mechanism. The cradle has
riveted to its underside a pintle which seats in a pintle socket se-
cured to the axle, by means of which the cradle and gun is rotated.

The top and main shield and an apron are provided for the pro-
tection of the personnel from gun fire.

The recoil mechanism is of the hydro-spring type. The recoil
cylinder is fastened to the gun lug and therefore recoils with the gun.
The piston rod, "being secured to the cradle head, remains stationary
during recoil. Throttling during recoil is obtained by the use of
three throttling bars, on the interior of the recoil cylinder, the piston
having three slots cut in it to correspond to the throttling bars.
During recoil the piston is stationary and the hydroline oil in the
cylinder is forced past the piston through the slots. As the throttling
bars, due to their increasing size, gradually close the slots in the
piston, the gun is gradually brought to a stop.

The counterrecoil mechanism consists of three nests of inner and
outer springs which function to return the gun to battery and serve
to partially check the recoil. The counterrecoil buffer consists of a
tapered rod secured in the end of the cylinder which enters the hollow
end of the piston rod, displacing the oil therein and preventing shock
when the gun returns to battery.

The elevating mechanism is of the double-screw type, consisting of
a screw pivoted to the rear end of the rocker, which is moved up or
down by the rotation of a bevel gear threaded on its interior surface.
This bevel gear is rotated by a bevel pinion operated by a crank
handle on either side of the trail



125




12G

Traversing is accomplished by means of a traversing shaft operated
by a handwheel on the left side of the carriage. This shaft is
threaded and passes through a nut which is pivoted to the cradle.
The nut being secured to prevent its turning, swings the cradle in
traverse, when the traversing mechanism is operated.

A lock is provided for locking the cradle to the trail in order to
relieve the elevating and traversing mechanisms of any unnecessary
strains during traveling.




CARRIAGE AND LIMBER HAULED BY TRACTOR.

Seats are supported on the axle on each side of carriage in front of
the shield for the cannoneers, when traveling. Foot rests are pro-
vided which also support the brake levers and ammunition carriers,
there being four of the latter which make it possible to open fire
quickly if necessarv .




CARRIAGE AND LIMBER IN TRAVELING POSITION.

The brakes are of the shoe type and may be operated from either
in front or rear of the shield, in the former case when traveling, and
in the latter case when in firing position.

Standard 56-inch wheels are used. See page 158.

The instruments provided for sighting and laying the piece include
line sights, a rear sight, a front sight, a panoramic site, and a range
quadran t.

Three kinds of fixed ammunition are used in the 3-inch gun,
models of 1902, 1904, and 1905, namely, common steel shell, common
shrapnel, and high explosive shrapnel. Each round is issued with



127




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128




129

projectiJes filled and fuzed. The weight of the projectile is 15 pounds
and the total weight of one round is 18.75 pounds.

3-INCH GUN MATERIEL, MODEL OF 1902.

This materiel includes the following:

3-inch field gun, model of 1902, 1902 or 1905 mounted on
carriage, model of 1902.

3-inch gun limber, model of 1902 and 1916.

3-inch gun caisson, model of 1902 and 1916.

Forge limber, model of 1902 and 1902 Ml.

Battery wagon, model of 1902, 1902 Ml and 1917.

Store limber, model of 1902 and 1902 Ml

Store wagon, model of 1902, 1902 Ml and 1917.

Battery reel, model of 1917.
The above materiel is entirely of American design and manufacture.



3-INCH GUN LIMBER, MODEL OF 1902.



The limber, excepting the spokes and felloes of the wheels, is of
metal throughout. The principal parts are the wheels, axle, frame,
ammunition chest, pole, doubletree, singletrees, and neck yoke.

The wheels and wheel fastenings are the same as, and interchange-
able with, those used on the carriage. The axle is hollow, of a single
piece of forged steel, the axle body being provided with lugs, to which
the middle and side rails of the frame are riveted.

The side rails are of channel shape, divided at the front, one branch
being led forward and secured to the middle rail near the pole seat,




REAR VIEW OF LIMBER.

while the other branch is utilized as a foot-rest support. The foot
rest is a perforated steel plate formed to shape and riveted to the
middle and side rails in front of the ammunition chest. The rear


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Online LibraryUnited States. Army. Ordnance DeptHandbook of artillery : including mobile, anti-aircraft and trench matériel → online text (page 7 of 19)