carriages and mounts series
TRANSCRIPT
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UNCLASSIFIED
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use; Sep 1963.
Other requests shall be
referred
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Materiel Command,
Attn:
AMCRD-TV,
Washington
DC
20315
AUTHORITY
USAMC ltr,
22
Jul
1971
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#MC
PAMPHLET
AMCP
706-342
THIS
IS
A
REPRINT
WITHOUT
CHANGE
OP OROP
20-242
RESEARCH
AND
DEVELOPMENT
OF
MATERIEL
ENGINEERING
DESIGN
HANDBOOK
CARRIAGES
AND
MOUNTS
SERIES
4RECOIL
SYSTEMS
'
-
D D C
APR
18
1968
C
STATEMENT
#2 UNCLASSIFIED
This
document is
subject to
special export
controls
and each
transmittal
to
foreign
governments
or
foreign
nationals
may
be
made
only
with
prior
approval of:
Army Materiel
Command,
Attn: AMCRD-TV,
Washington,
D.C.
20315
HEADQUARTERS,
U. S. ARMY
MATERIEL
COMMAND
SEPTEMBER
1963
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PREFACE
This handbook on
Recoil Systems has
been
pepae
m
ofa ries
on Carriages
and Mounts. It
presents
information on the fundamental Olu
principls
of
re-
coil
systems and the design of recoil systems and their o-po.g
Text and line illustrations were prepared by
The
Franklin Iwiktfte under contract
with
Duke
University, with
the technical assistance
of
the Ordnance
Weapons
Command.
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TABLE OF
CONTENTS
Page
P
EFAC ...............................................................
i
Lar OF FIoURES
v
lssr oP SYMUM ........................................................
vii
L INmmTOUCToN
....................................................
I
A. General
.................................................. I
B. Function of
a
Recoil Mechanism
............................
I
1. THE
REIm SYsTEM ...............................................
3
A.
Definitions
................................................
3
B. Description
of the Basic Components ........................
3
Hi. DESCRIPTION OF
THE
RECOIL
CYCLE .................................. 5
A. Single Recoil System, Sequence of Operation
.................. 5
B. Double Recoil System, Sequence of Operation
................. 5
IV. PRINCIPAL TYPES
OF RECOIL MECHANISMS ............................. 5
A.
Hydrospring Type .........................................
5
B.
Hydropneumatic Type ......................................
5
C. Types
of
Counterrecoil
Buffer
...............................
6
V.
OPERATING CHARAC TERISTIC S.... .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. .
6
A.
General
..................................................
6
B.
The
Recoil Brake ........................................
6
C. Hydrospring
Mechanism ................................... 7
D. Hydropneumatic Mechanism
................................
9
E.
The Puteaux
Mechanism
....................................
10
F. The
Schneider
Mechanism
..................................
I
G. The Filloux Mechanism ....................................
13
H. The St. Chamond Mechanism
................................
13
1. Double
Recoil System
...................................... 13
VI. SELECTION OF A RECOIL
SYSTEM
...................................... 16
A. General ..................... ...........................
16
B. Requisites
of
the
Recoil System
.............................. 16
VII. PRELIMINARY
DFSIGN
DATA
............................................. 16
A.
Velocity
of
Free Recoil ......................... ........... 16
B. Recoil
Force .............................................. 17
C. In-Battery Force ...........................................
17
Li
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TABLE OF
CONTENTS (Continud)
Page
D.
Velocity
of
Counterrecoil
................................... 18
E. Buffer Force
..............................................
18
VIII.
DESIGN OF RECOIL
MECHANISM
COMPONEN1T ..........................
19
A.
Suggested
Materials ........................................
19
B. Recoil
Piston Rod
.........................................
19
C. Recoil Piston
..............................................
20
D. Packings ..................................................
20
E. Belleville Springs
..........................................
21
F.
Recoil Cylinder ............................................ 22
G.
Recuperator, Hydropneumatic ...............................
23
H. Recuperator,
Spring Type ...................................
23
I. Counterrecoil
Buffer .......................................
23
J. Floating Piston
............................................
24
K. Regulator
.................................................
25
L
Recoil
Throttling
Valve
.....................................
25
M. Regulator Valve ........................................... 27
N. Manufacturing
Procedures ..................................
28
0. Maintenance
Features
......................................
28
IX. Smos REcxxL
SvsrEM
CALCULATIONS
29
A.
Propellant
Gas
Force vs.
Time Curve .....................
.. 29
B.
Recoil
Force Chart
........................................
29
C.
Recoil Calculations ........................................
29
D. Analysis of Fluid
Behavior During
Recoil
....................
31
I. Recoil Force ...........................................
31
2
Orifice
Size
.............................................
32
3. Losses in the Hydraulic
System
...........................
33
4. Compressibility
of Hydraulic Fluid
........................
34
5.
Analysis
for
Recoil
Throttling
Valve
.......................
35
E.
Counterrecoil Calculations
.................................
38
X. DESIGN
OF CONCENTRIC RECOILMECHAKIS&
..........................
42
A. Introduction
..............................................
42
B. Types
of
Concentric
Recoil Mechanism .......................
42
C.
Recoil
Calculations,
Concentric
Types ........................
42
D.
Orifice Design,
Concentric
Types
............................
43
E. Spring
Design, Concentric
Types ............................
44
XI.
DESIGN OF DOUBLE
RECOIL SYSTEMS ..................................
46
A.
Introduction
..............................................
46
B.
Recoil
Forces .............................................
47
C. Procedure for
Dynamic Analysis .............................
47
I. Nomenclature
..........................................
47
2. Detailed Discussion
.....................................
48
XII.
RECOIL SYSTEMS
FOR SMALL ARMS
...................................
60
A
.
Introduction
..............................................
60
S" iii
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TABLE
OF
CONTENTS (Concluded)
Page
B.
Design and Operating
Characteristics
of
Ring
Springs ..........
60
C. Design
and
Operating Characteristics of the Sleeve Brake
.......
63
D. Design
and Operating Characteristics
of
the Hydrospring
Adapter 66
XIII.
SUPPLEENTAL DESIGN FEATmES
...................................
66
A. Muzzle
Brakes...................... ..............
66
B. Liquid
Reserve
Indicator,
or
Oil Index ....................... 67
C. Replenisher...............................................
67
XIV. SAMPLE CALCULATIONs SiNGLE RECOL............................. 68
GO sy ............................................... ..............
77
REUCS.......................................... 79
INDIEX
................................................................
80
iv
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LIST
OF
FIGURES
Figwe
Page
I
Weapon
Showing
Recoil Mechanism
(Recoil Brake
and Recuperator)...
2
2 Diagram
of
Recoil
Mechanism
Types (General)
......................
3
3
Diagram
of Hydrospring
Types
....................................
4
4 Diagram
of Hydropneumatic Types .................................
4
5 Recoil Mechanism Force
Chart
....................................
7
6
Methods
of Orifice
Area
Control
(Right
Sections
Are at
Pistons) .......
8
7 Hydrospring
Recoil Mechanism
(Schematic)
.........................
9
8
The Puteaux
Mechanism
(Schematic)
................................
10
9 The
Schneider
Recoil Mechanism
...................................
12
10
The Filloux
Recoil Mechanism .....................................
14
II
The
St. Chamond
Recoil Mechanism
...............................
15
12
Recoil Force.
System.
17
13 Rod-Breech
Ring
Attachments
.....................................
19
14
Typical
Packing
Assembly .........................................
20
15
External
Buffer
...................................................
24
16
Internal Buffer
...................................................
24
17
Respirator
.......................................................
24
18 Floating
Piston
...................................................
25
19
Piston Flange
Loading Diagram
....................................
25
20
Regulator,
Sh-iwing Oil
Flow
Paths ................................
26
21
Recoil
Throttling
Valve ...........................................
26
22
Regulator
Valve
(Valve Closed
for Counterrecoil)
....................
27
23 Propellant Gas
Force-Time
Curve During Projectile
Travel in
Bore .... 30
24
Propellant Gas
Force-Decay
Curve
After Projectile Leaves
Muzzle
....
30
25
Forces and Reactions
on
Recoiling
Parts
............................
32
26
Oil
Chambers
of a
Recoil Mechanism
...............................
34
27
Counterrecoil
Force
Chart .........................................
38
28 Functioning Components
During Counterrecoil ......................
39
29 Concentric
Recoil
Mechanism (Concentric Spring
Type)
...............
43
30
Concentric
Recoil Mechanism
(Multiple Cylinder
Type)
...............
43
31 Concentric
Recoil Mechanism
with
Separate
Counterrecoil
Assembly
.... 44
32
Force-Time
and Acceleration-Time
Curves
..........................
45
33
Velocity-Time
Curve
of
Recoil .....................................
45
34
Velocity-Distance
Curve of
Recoil ..................................
46
35
Gun With Double
Recoil Mechanism
...............................
47
36
Preliminary
Forces
of a
Double
Recoil
System
.......................
48
37
Forces
on a Double
Recoil
System
..................................
50
38 Acceleration
Diagram
of
a Double
Recoil System .....................
51
39
Applied
Loads
and Reactions
on Cradle
............................
54
,41 Ring
Spring W
ith Single
Spring Element
............................
61
41 Ring
Spring Constants
and Efficiency ...............................
62
42
Load-Deflection
Diagrams of
Ring Springs ..........................
63
43 Load-Deflection Diagrams of
Similar Ring Springs ...................
63
44 Sleeve
Brake Recoil Adapter Disassembled
.........................
64
v
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UST OF FIGURES (Concluded)
Figure Page
45
Force-Friction Relations
of
a
Sleeve
Brake Mechanism
................
65
46
Force-Displacement Diagram of a Sleeve Brake Adapter
.............. 65
47 Oil
Index
67
48
Replenisher
67
49 Recoil Force
Chart
for Sample Problem ............................. 69
vi
vi4
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A
"LUST OF SYMBOLS"
a Maverage recoil acceleration during
At F. available counterrecoil
force
before throttling
ab macceleration during buffing
Fb -
total
buffer
force
a
- counterrecoil orifice area
F
- buffer
net decelerating
force
a. - recoil orifice area
F - hydraulic
resistance of counterrecoil orifice
a
-
buffer
orifice area F&
= initial Belleville spring load
a,
- acceleration
during
counterrecoil F,
- coil spring force
of
recoil throttling valve
A -
effective
area
of recoil
piston
F - initial coil spring load
A, -
contact area
of
packing on cylinder
wall
Fc,
- net counterrecoil accelerating force
Ab
-
effective
area
of buffer
piston
F, - frictional resistance of slides during
counter-
A, - cross section area
of
control
rod recoil
A,.
- area
of
counterrecoil
pisto-
A;4p'ywnti-t
F,
-
propelbunt gaSorce
system)
F. - hydraulic resistance
of
recoil
brake
As
- bore area
of gun
tube
F,
- force
on counterrecoil piston
A.
-
peripheral discharge area
of
recoil
throttling
F,
-
force on counterrecoil piston
valve
FR -
recuperator
force;
same as force
on
floating
A, -
root
area of
thread
piston
At -
recuperator
area;
same as
area
of
floating F,
-
spring
load
in general;
the combined load
of
piston
coil
and
Bclleville springs
A,
-
root area
of valve stem F, - combined
initial
spring load
of coil
and
A,
- effective pressure
area
of
throttling valve
Belleville springs
b - width
of
packing
F,, -
spring
force
when buffers
are contacted
c -
open periphery
of
valve
head Fe -
radial
force
of
packing on cylinder
C, - counterrecoil
orifice coefficient
h
- velocity
head
C.
- orifice coefficient in
general
or
for recoil h, = lift
of recoil throttling
valve,
coil spring
orifice
active
Dt
- inside
diameter
of recoil cylinder h, - lift
of
recoil throttling valve, both springs
E, - kinetic energy of
counterrecoil
active
E,
-
kinetic energy
of
recoil
k
-
stress concentration factor
f4 - total frictional resistance
of packing in recoil K - total
resistance
to recoil
brake and counterrecoil
cylinder K. -
resistance
offered by
elastic medium
of
- hydraulic
resistance of recoil
orifice
during recuperator
counterrecoil
Kb =
Belleville
spring rate, recoil throttling
valve
f,
- hydraulic resistance at each
restriction in K, - coil spring
rate,
recoil
throttling valve
flow
path
other
than
controlled
orifice K, = frictional resistance of cradle slides during
-
total frictional
resistance of packings recoil
-
frictional
resistance
of
a packing assembly
K, =- spring rate in general; spring
rate
of corn-
= frictional
resistance of
packing in recuperator
bined
coil and
Belleville
springs
F = force
tending
to accelerate
recoiling
parts
K,
=
pressure factor
F
=-
static
force
of recuperator
in battery K,
= recoil rod
force
-F
static
resistance
to counterrecoil L
=
length
of recoil
F
2
-
recuperator
force, end
of
recoil
L,,
=-length of
counterrecoil stroke to contact
F.
=
net
accelerating force or inertia
force
of
buffers
recoiling
parts
M
=
mass equivalent
of
projectile and propellant
Symbols
peculiar
to
double
recoil
systems
are
listed
in
gas
paragraph 149
and those for recoil systems
for
small
arms Mb = bulk
modulus of
fluid
in paragraph
187.
M, = mass of recoiling
parts
vii
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n
-
polytropic
exponent Av - change
in
velocity
n - subscript
denoting
value
at stated interval v, - average
velocity during AS
n-I
- subscript denoting value
preceding the v% -
velocity of counterrecoil
during
buffing
stated
interval v/ - maximum
velocity of free recoil
P , pressure in recoil
brake cylinder
Av/
- change in free recoil
velocity
P-
pressure
drop
across
counterrecoil
orifice
vyt
-
velocity
of
free recoil
at
time,
t,
P",
oil
pressure before throttling through
v/2 -
velocity
of free recoil at time, 12
counterrecoil
orifice
V., -
muzzle
velocity of projectile
P, - oil pressure
before throttling
through
recoil v. -
velocity
of
flow through
orifice
orifice
during counterrecoil v,
- counterrecoil velocity
P0 minimum recuperator
pressure, in-battery Ai, - change
in
counterrecoil
velocity
P, gas
pressure at end of recoil
j
-
velocity of
floating
piston
P
2
gas
prcssure when buffers are
contacted
V
0
- gas volume,
in-battery
P. axial
pressure
in packing V, - gas volume at end
of
recoil
P#
buffer pressure V
2
-
gas volume
when
buffers are
contacted
P,
propellant
gas pressure AV -
gas displacement
P* pressure rise
caused by
orifice
w -
density of
fluid
P.-
maximum fluid pressure
W.. - available energy
in
recuperator
for counter-
AP. - pressure
drop
across
recoil orifice
during
recoil
counterrecoil
W, weight of
propellant
charge
Pp
-
proof
pressure
Wp
-
weight
of
projectile
P,
recuperator pressure or equivalent
pressure W, - weight
of recoiling parts
of spring
W,
- erergy required to overcome
static resistance
P -- radial pressure
in packing x
- distance of recoil at time
t
P, -axial pressure
in packing produced
by
Ax
- distance recoiled during At
spring
x#
- distance of
buffer
travel at
any
time
t
P
- gas
pressure
at
any
position
of
recoil
x - displacement of control
rod
P,
w
fluid
pressure on packing x, -
distance of
counterrecoil
at any time t
Q - rate of flow
Ax,
- distance
counterrecoiled
during At
-
rate
of flow through counterrecoil orifice
I =
angle of elevation
- rate of flow through
recoil orifice during X = in-battery
sustaining fa-tor
counterrecoil
- coefficient
of friction
R - secondary recoil
force - leakage
factor
Sb
-
length of buffer stroke
p
-
mass density of
fluid
S
-
- factor
of safety
- radial stress
t
- time -
tensile
stress;
hoop
stress
At - change in
time
-
yield
strength
Vs
-
recoil velocity
- maximum shear
stress
viii
, a-
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CARRIAGES
AND
MOUNTS
SERIES
RECOIL
SYSTEMS*
1. INTRODUCTION
the
other
side
represents
the total momentum
of
the
projectile and propellant
gases
moving
in
the op-
A. GENlER.L posite
direction. The
only
unknown value, the
velocity
of
free
recoi ,
can
be
determined
by
ap-
I. This
is
one of
a series
of
handbooks
on
Car- propriate
substitutions
in
Equation (Ic). Once
this
riages
and Mounts.
This
handbook deals with
velocity
is
found,
the
kinetic
energy of the
recoiling
the design
of
recoil
mechanisms.
mass can be calculated
(see Equation
3a
Par.
78).
At this
stage, the method by which the kinetic
3 FUNCTION
OF
A
RECOIL MECHANISM
energy
is
dissipated
becomes
the
sole
basis
of
design
of the recoil
mechanism.
2. A
recoil
mechanism
moderates
the
firing loads
4.
It
would
be possible
to attach the gun
tube
on the supporting structure
by prolonging
the
time rigidly
to its carriage, thereby exposing
the structure
of
resistance
to
the
propellant
gas forces.
As
the
to the
full propellant
pressure force
which
ma y
gas
pressure
propels
the projectile
toward
the
exceed two million
pounds in large guns.
However,
muzzle,
it exerts an
equal and opposite
force on
the to
be strong
enough
to sustain
this tremendous
load,
breech,
which
tends to drive the gun
backward.
the
structure would become
overwhelmingly
large
The main purpose
of
a
recoil mechanism
is to and unwieldy. The
expanse
of thz
base
to
providt
cushion
this force and limit the
rearward
movement,
stability,
that is,
to
prevent tipping over,
would be
3. The dynamics
of recoil presents a study
in the enormous.
Pistols and
shoulder
arms of
the
closed
conservation
of
momentum.
From mech,,,II.S
We breech
type
are
designed
to this concept.
hut they
have
the
expression
for
a
force,
rely upon
the human body
to provide the
recoil
resistance.
F =
)
(1)
5. In practical
design
of
larger
weapons,
the gun
is
permitted
to recoil,
or
move back, a prescribed
where:
m
-
mass,
distance and
against
some
predetermined resistance.
V - velocity. Figure
I shows
a
weapon
with a recoil
mechanism.
The
function
of
a
recoil
mechanism
is to
absorb the
The
forces
tending
to separate two
bodies are
equal energy
of recoil effectively and then
return the
gun
and
opposite
in
direction,
thus,
equating the
forces to the "in-battery"
position.
The
large rearward
in
the above
equation
we have
thrust acts
for
a very short time,
only so long as the
F,
-d(m-
-) -
F
2
-m
2
X-
2
)
(la)
propellant
gas
pressure
acts.
In order
to
confine
the
dt
dt
supporting
structure
to reasonable
size
and
weight,
and
to
achieve sttibility
with
a
relatively
small
firing
and
d(mIV,)
- dm
2
, ).
(lb)
base,
it
is
necessary to
prolong
the
duration
of
Integrating
we
have
resistance
to
the impulsivce
force
of
the
propellant
m19'1
-
m
2
v
2
(Ic)
gas.
6. The
propellant
gas pressure
force,
instead
of
This principle
is
'cctly
applicable to the recoil being applied directly to
the
carriage
structire,
activity
of Ivins where one
side of Equ,,tion
(Ic)
merely accelerates
the gun and other
recoiling
parts
represents
the
momentum
of
the recoil'ng
part%
and
in
their
recoil
motion. This
motion
is retarded
by
* Prepred by
Mas.in Regina.
Latbnratoriei
for Research a predetermined
and
controlled
force.
The
retard-
and
I[mlonpmmnI of
I
he Iranklin
Institute.
ing
force
is the one
which must
be
taken
by the
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8/9/2019 Carriages and Mounts Series
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0
0 E -
0 4
w C
0 0
U
0
4
hI 0
U) t
0.
0.
o
8
U
- 0
5 0
oC
0
1
I,
*
z
*1
0
0
I
hI
C
I
a
S
U
2
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8/9/2019 Carriages and Mounts Series
13/92
structure.
It
is
much
smaller than the
original trolled
and
limited
to certain
parameters by one or
-
propellant gas force, because
it acts
over
a much more recoil
mechanisms.
greater
interval
of
time
and
an appreciable
dis-
10.
The
recoil
mechanism is
that component
%f
tance;
the
longer
the distance,
the smaller the force,
a recoil system which
absorbs
and stores
the recoil
The resistance
to
motion
is
provided mostly
by the
energy
and
then
returns the gun to battery
position.
recoil mechanism
and
partly
by gun
slide
friction. II. There are two types
of recoil systems: a
A detailed analysis of
this
activity is
discussed in
single and a
double system. A single recoil system
Parts D.I and D.2
of
Chapter
IX.
is one
wherein
the recoil mechanism (or mecha.
7.
The product of recoil
distance
and
retarding nisms)
has its recoiling parts moving,
as a single
force
is
recoil
energy,
which is
a primary criterion
coordinated
unit,
in one
direction
(see Chapter
III,
* in the
design
of a
rec,)il
mechanism.
When
the Part A).
weapon
is
fired, recoil
begins immediately.
The
12. A
double
recoil system is
one in
which
the
energy of
recoil is developed
in the short time
the
recoil
mechanisms
control two
separate units of
propellant gas forces
are
acting. This energy is recoiling
parts,
with
both
coordinated
units
moving
expended in several ways, namely:
(1) a small
in
the same general rearward
direction, but in paths
amount is stored in
deflecting
the
structure and
not
necessarily parallel
(see Chapter
11, Part
B,
ordinarily may
be
safely
ignored;
(2)
some is and Chapter
XI).
absorbed by gun-slide
friction;
(3)
the
greatest por-
tion
is
dissipated by
the
recoil
mechanism;
and
(4)
a
sufficient
amount
is stored in the
recuperator a*
ESCRi T1ON OP THE aSIc COMPONErS
to return
the gun to the in-battery
position.
13.
A
recoil
mechanism is
comprised of
three
8. While
returning to the in-battery
position, basic
comr -nents:
a
recoil
brake, it
counterrecoil
the moving
parts
acquire
a
counterrecoil
energy.
mechanisr ind
a
buffer
as shown
dilrammatically
Some means
must be
provided
to absorb
this
in
Figs.
and 4. The recoil
brakt
consisL of
a
energy
and
ease
the unit into the
in-battery position. hldraul
ilinder
and piston
assetibly.
As
the
This is
accomplished
by
the counterrecoil buffer.
pistoi
yes within
the cylinder,
a
force
is gener-
ated by
restricting the
flow
of hydraulic fluid
i,=-
the pressure chamber of the
cylinder.
The
magni-
!1.
THE RECOIL SYSTEM
tude of
this restricting force
is
a
function of the
flow of fluid
through one or
more
orifices,
whose
size
is
regulated to provide the
desired recoil
velocity
and
pressure curves. The recoil energy
absorbed
9. A recoil system
is
defined
as
an
assembly
of
by this restricting force
is dissipated as
heat.
components
whereby the forces
acting
on
a
gun
and
14.
The
counterrecoil mechanism
is composed of
its related mount during a firing
cycle
can be con-
a
recuperator and counterrecoil cylinder assembly.
- RECOIL BRAKING
- OIL PLUS
SPRING
HYDROSPRING
COUNTERRECOIL
- SPRING
BUFFING
OIL
MECHANISM
r RECOIL
BRAKING -
OIL
PLUS COMPRESSED
GAS
HYDROPNEJMATIC
4
COUNTERiRECOIL
-
COMPRESSED
GAS
B-
N I
RESPIRATOR (AIR)
.__BUFFING OIL
Figure
2. Diagram
of
Recoil Mechanism
Types
(General)
3
F
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SPRINGS
ARE
CONCENTRIC
WITH
CONCENTC
TYPE-
BRAKE
ROD IN ONE
CYLINDER
ALL
COMPONENTS
ARE
CONCENTRIC
HYDROSPRING
WITH GUN
TUBE
IN
ONE
CYLINDER
RECOIL
MECHANISM
BRAKE
AND
SPRING
ARE IN
SEPARATE
CYLINDERS
SEPARATE
TYPE
SPRING
IS
SEPARATE
FROM
BRAKE
AND
IS
CONCENTRIC
WITH
GUN
PrW.
3.
Diagram
of
Hfydroqpri
Typeo
INDEPENDENT
TYPE
TOTAL
COUNTER-
RECOIL
STROKE
BRAKE
SEPARATE
FROM
DIRECT
RECUPERATOR
CONTACT
HYDROPNEUMATIC
R
B
RECOIL
RECOIL
BRAKE
- RECUPERATOR
-
BUFFER -
RESPIRATOR
MECHANISM
I
DIRECT
OIL
FLOW
BETWEEN
FLOATING
CYLINDER
AND
RECUPERATOR
PISTON
I
SPEAR
DEPENDENT
TYPE
LAST
PART
OF
COUNTERRECOIL
STROKE
DASHPOT
Flowe
4. Dhagram
of Hydroprmmatic
Type
The
latter
may be
a
separate
unit
or
it may
be the
During
recoil, the spring
or gas
is compressed
recoil
brake components
operating
in
reverse.
The
further,
storing
the
additional
energy
needed
for
terms counterrecoil
mechanism
and recuperator
are
counterrecoil.
While
in
transit,
gun
locks,
either
sometimes
used as
synonyms.
However,
to avoid
with
or without
the
aid
of the
in-battery
force,
hold
confusion,
the recuperator
is defined
here
as the
the
recoiling
parts
in
position.
equipment
which stores
some
of
the
recoil energy
15. The
buffer functions
similarly
to
the
recoil
for counterrecoil,
whereas
the counterrecoil
mecha-
brake;
it absorbs
the
energy
of
counterrecoil.
There
nism
is
defined
as
the unit
which
returns
the recoil-
is
sufficient
recuperator
energy
to drive
the
recoiling
ing parts
to battery.
It derives
its
energy
from the
parts
into
battery
at
an
appreciable
velocity.
If
this
recuperator.
The recuperator
can
be
of
either
the
were not
controlled,
an impact
would
occur,
which
hydrospring
type
or the hydropneumatic
type.
The might
cause
the
weapon
to
nose
over,
create
struc-
hydrospring
type
stores
the
energy
required
to tural damage,
or both.
The
buffer
is usually
a
return
the gun
to the battery
position
in
a
mechan-
dashpot
type
of
device.
ical
spring,
or
springs.
The hydropneumatic
type
16.
The components
are
described
above
as
stores this
energy in compressed gas. There is
separate units,
which sometimes is
the
case.
Fre-
always
some
recuperator
force present
to hold
the
quently,
though,
they are
integrated
into
a
single
recoiling
parts
in
battery
at all angles
of
elevation,
mechanism.
However,
whether
separate
or
inte-
4
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gral, all
components are
interdependent
and func-
weapon
is now in
battery
and ready
to be loaded
/ tion as one
unit.
and fired again.
S. DOUBLE RECOIL
SYSTEM,
SEQUENCE OF OPERATION
111. DESCRIPTION OF THE
RECOIL
CYCLE
22. In a double
recoil system, two masses are
joined
to
each
other and to
the fixed
structure by
recoil mechanisms. The
primary
recoiling
parts
A.
SINGLE RECOIL SYSTEM,
SEQUENCE
OF OPERATION consist
of gun tube, breech housing and operating
17.
As soon
as the gun is fired
and
the
projectile mechanism, breechblock
assembly,
and
those parts
starts forward, propellant
gas pressure accelerates of
the recoil mechanisms
not
fixed to the cradle.
the recoiling
parts
backward.
This motion
is
re- In some
instances,
the
recoil piston
rod, the
counter-
sisted by the inertia of the recoiling parts,
friction, recoil piston rod, and the
buffer are
attached
to and
and
the recoil mechanism.
The
force exerted by move with the recoiling parts; in others, these
items
the
recoil mechanism
comes from both
the recoil
are
fixed to
the cradle
while their associated
cylin-
brake and recuperator.
Acceleration of the
recoil-
ders constitute
a portion
of
the
recoiling
parts.
ing
parts
takes place
during
the
time of travel of
The secondary
recoiling parts are composed of
the
the
projectile
in
the
bore plus the time
of pressure cradle,
top carriage, that
portion of the
primary
decay
after
the projectile leaves
the
muzzle.
recoil mechanism that
is affixed to the cradle, and
18.
The
retarding
force
occurs
over the
entire
those
parts
of
the
secondary
recoil
mechanism
recoil stroke.
At
the
very
instant of
firing, only which move with the top
carriage. The
secondary
recuperator and
friction
forces
are
available. After system action
is somewhat
modified by
the
fact
that
motion
begins, these
forces
are augmented
by
the the secondary
system does not begin to move until
hydraulic
throttling force.
The
recoiling
parts the
primary is definitely under way.
Its recuperator
reach
maximum
velocity
when the retarding
force resistance
and
inertia are
sufficient
to delay
the
is equal to the propellant
gas force, and then deceler-
start of motion.
The
primary system is well
on
ate
until
motion
ceases.
Meanwhile, due to
the the
way
in
counterrecoil
before
the secondary
has
further compression
of
its
spring
or gas,
the re- fully recoiled. Ordinarily,
the primary is in battery
cuperator
force
increases
gradually, storing the
while
the secondary is
still in counterrecoil.
energy
needed
for counterrecoil.
19. At
the
completion
of the recoil
stroke,
the
recuperator begins to return
the recoiling
parts
into IV.
PRINCIPAL
TYPES
OF RECOIL
battery.
Its force can never be
less than
that re-
MECHANISMS
quired
to hold
the
gun
in
battery. Therefore, that
part of the area of the
force-distance curve
which
represents
stored
counterrecoil
energy
is
somewhat
A.
P.YDROPRUNG
TYPE
predetermined.
23. The hydrospring mechanism
utilizes a me-
20.
A
quick return to battery is
an advantage in chanical spring for the recuperator
and
a hydraulic
rapid-fire guns
but is
undesirable in
single-fire
guns. system for
recoil
and
buffing. Sometimes,
the
Here,
high forces cause ptoblems
in
strength aad spring is mounted concentric
to the gun tube; in
stability. As counterrecoil
velocities are
sometimes
other arrangements,
it
is
concentric to the recoil
limited to 2
or
3
feet
per
second, even more restric- mechanism;
or
the spring
may
he
a
separate
unit.
tion
of hydraulic
flow
than in
recoil
may be neces-
The manner
of
mounting
depenJi upon the
size
of
sary.
spring needed, the available
space
and
its
location,
21. Before the counterrecoil
stroke is completed, and on the effects of eccentric forces.
the moving parts contact
the
buffer,
which
is dc-
signcd to
absorb
the remaining counterrecoil
energy.
The moving parts should stop
just
as they . MYDRONEMATC TYP
reach the
in-battery
position. The
recuperator
24.
The
hydropneumatic
mechanism
uses
com-
force
is
still acting, but at
its
minimum value.
The pressed
gas
for
its
recuperator,
usually
dry nitrogen
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because
of
its
relative
inertness. It may
be either
is not applicable at
the beginning
because the
recoil
"independent"
or
"dependent,"
or variations
of
resistance
should
not
exceed the propellant
gas
these
two.
force if prompt recoil
motion is
desired.
25.
In
the independent
type, the recuperator
is 29. The total resistance
is
a
combination
of a
an entirely separate
unit
from
the
recoil
brake hydraulic force,
a
spring
force, which
may be
(refer
to
Figures 9
and
10).
The
piston
rods
of
mechanical
or from compressed
gas, and friction.
both brake and recuperator
are joined
directly to
Nhichever combination
is
used, it works
as a unit,
the recoiling
parts. As the gun
recoils, hydraulic
the parts affecting each
other as
they act simul-
fluid or
oil is
forced
into the compressed
gas
taneously.
Therefore, the entire
system
must be
chamber. As the fluid
compresses the gas
still analyzed
as a
unit.
further,
the pressure increases.
During
counter-
recoil, this action
is
reversed. The gas
and fluid
may
be
separated
by a floating
piston,
or they ma y
be in direct
contact.
If in direct
contact,
sufficient
30.
Since the
recuperator
force-distance
curve
is
oil must be provided
so
that
gas cannot escape
somewhat determined
by
its battery position
force,
through the
port to the counterrecoil
cylinder,
it is
necessary to
adjust
the
hydraulic
brake curve
26. In the dependent
case,
only the
recoil piston
so
that the
total
curve
will
be
as
desired
(see Figure
rod
is
joined
to
the recoiling
parts (refer
to Figures
5). After the
friction
and recuperator
curves
are
8 and
11). Fluid
is
forced
from
the
recoil brake
known,
their ordinates
may
be subtracted
from
cylinder
into
the recuperator,
where
it is throttled.
those
of
the total resistance
curve.
The
differences
The
recuperator normally
is
connected directly
to
of
the ordinates form the
design
brake curve.
the recoil
brake
cylinder,
but
a floating
piston
31.
The
recoil brake
force,
at any
point
along
separates
gas
and fluid.
the
stroke,
depends
upon
the
recoil
velocity
and
orifice area at that
point. It
is therefore necessary
to vary
the orifice
area
from
point
to
point
to suit the
C.
TYPES
OF
COUNTERRECOIL
BUFFER
changing
velocity
and force.
This may be
done in
27.
Buffers
operate
by
means
of
a controlled
any
of several
ways,
or in combinations
thereof.
restriction
of hydraulic
flow
and are
of two general
Figure 6
illustrates
some
of these methods.
types.
One acts
over
a
short distance
during the
32.
A throttling
bar (Fig.
6a), whose
cross
sec-
end
of
the counterrecoil
stroke.
The
other, where
tion
varies along its
length, is
fastened along
the
lower
forces
and
finer
control
over
velocity
are
cylinder
in
such
manner
that
it
cannot
move
longi-
needed,
acts
during
the entire
length
of
stroke.
tudinally.
This
bar
passes through
a
fixed-area
orifice in the piston.
As the
piston
moves, the
net
orifice
area changes with corresponding change
in
V.
OPERATING CHARACTERISTICS
restriction
to fluid
flow. The same
effect
may
be
had
with
a
solid
piston and a
varying groove
cut
into the cylinder
wall
(Fig. 6b). Either
method
A.
GENERAL
offers
excellent
control
over
the pressure
curve.
28.
All recoil
mechanisms work on some
com-
Two bars or grooves
diametrically
opposed
are
bination
of
the
same
basic principles;
that of recommended
for a balanced pressure
load on the
providing
a controlled
resistance over
a set distance
piston.
to
check
the
motion of
the
recoiling
parts,
then 33.
Another method
varies orifices through
the
returning them
to the firing position
and
providing
piston
(Fig.
6c). A
rotatable
disk
with matching
a
sufficient
restraint
to hold
them in that position
holes is assembled
to the
piston. A
projection of the
at
maximum elevation.
This
resistance
to
recoil disk
is guided by a
spiral groove
in
the cylinder
should
be nearly
constant,
since, for a prescribed
wall.
As
the
disk rotates,
the orifices
change in
recoil
distance,
this will
produce
the
smallest
size. Again, excellent control
is possible.
possible force on the
structure (see Figure 5).
The
34. Controlled
throttling
may bK attained by
use
area under
the force-distance
curve
representh
en- of
a
perforated sleeve
inside
the
cylinder
(Fig. 6d).
ergy and, clearly,
a
rectangular
curve
will
yield the
Holes are properly
spaced so that those
back of
the
lowest
peak force.
However,
a
rectangular
curve
piston provide the restriction during
the
first
part
6
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ORDP
20-342
_______________________________________
ORIFICE
-
(a)
THROTTLING BAR
FIXED
TO CYLINDER
-ORIFICE IN PISTON
ORIFICE
(b) GROOVE
OF
VARYING
DEPTH IN CYLINDER
WALL-
PISTON
SOLID
ORIFICE
(c)
SPIRAL
GUIDE GROOVE
IN
CYLINDER WALL-
ROTATING
DISK
ON
PISTON
______________________________ORIFICE
0
0 0
00
0
00
o Go
oo
LH0
0
(d)
PERFORATED
SLEEVE
INSIDE
CYLINDER
_______________DVJALVE
(
(e)
CYLINDER
WITH
THROTTLING
CONTROL
VALVE
Figure
6.
Methods
of
Orifice
Area
Control
(Right
Sections
Are
at
Pistons)
n
nn
II II
I
I
I
I
I
I I
I i i i
S
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GUN
LUG--
GUN
i
r
GIE
9_--RAILS
RECUPERATOR
RECUPERATOR
-RECuPERATOR
COUNTERRECO
IL
PI
STONSPIGITO
RD
RECOIL
CYLINDER
F--RECOIL
PISTON ROD
.- THROTTLING
BAR
RECOIL
PISTON-
71
I I.
IL
CAVITY__-
DASHPOT/
Figure
7.
Hydrospring
Recoil
Mechoanism
(Schemofie)
31.
The
advantages
of a
hydrospring
system
are:
ditions.
a.
Simplicity
of design.
d. The capacity to
absorb
small modifica-
b.
Ease
of
manufacture.
tions
of the
weapon
without
requiring
c.
Low initial
cost.
recoil
system
redesign.
d.
Rapidity
of
repair
in
field.
e.
Relatively
long
recoil
is possible.
e.
Fewer
seal
or packing
problems.
f.
Flexibility
of design
approach.
The
disadvantages
are:
g. Adequate
warning
of
imminent
failure.
a.
Unpredictable
spring
life.
h.
Low
field
maintenance.
b. High
replacement
rate.
Disadvantages
are:
c. Bulkiness.
a.
Specialization
required
in
manufacture,
leading
to
high
cost
and
some
difficulty
D.
HYDROPNEUMATIC
MECHANISM
in
procurement;
although
it lends
itself
to
mass
production,
fitted
or
select
38.
The
points
in favor
of the
hydropneumatic
assembly
is usually
necessary.
system
are:
b.
Maintenance
in
storage
requires
great
a. Reliability.
care
to
avoid
deterioration
and damage
b.
Durability
because
of
little
mechanical
by internal
corrosion,
particularly
with
articulation.
leather
packing.
c. Smooth
action,
because
gas
pressure
c. Variation
of gas
pressure
with
ambient
can
be
finely
adjusted
to
varied
con-
temperature
affects
recoil
velocity
an d
9
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distance. This
may
require
some form is
not
self-sufficient, being
a simple hydraulic unit
of compensation.
which
merely
provides
a
force to retard
recoil.
d.
Greater number of internal cylinder The magnitude of the
force
is regulated
by
throttling
walls
requiring accuracy of form
and
in
the
recuperator.
The
recoil brake
comprises a
high surface
finish.
Dents
or
scratches cylinder,
piston,
and
piston
rod. The
recuperator
in
the
inside
walls cause rapid failure of
contains
a
regulator,
a
throttling
or control
rod,
a
the
packing passing over them. floating piston,
and
other associated parts.
e. Difficulty of maintaining
high rate
of
41. The
regulator
has
three cylindrical sections,
fire because ofeffect of heat
on packings the
ends, or heads, being much larger in diameter
and antifriction
metal.
than the middle section.
It is
fixed
in position, being
39. There is a great variety of possible designs held in place by the closure at the breech end
which
of hydropneumatic recoil
systems for the same gen- is threaded to the recuperator. The
front
head is
eral performance, as in the
case of
the hydrospring.
hollow
and
fits
the
cylinder
bore. Its rear
wall
con-
In the following sections, from E to H, several
exist-
tains one-way valves which permit fluid passage
ing
designs are
described. These
are
presented as only
during
recoil. The
front
wall is
a flat plate
some examples of past experience, but are
not
in-
having a central
orifice.
The regulator
is
bored
tended to
put any
limit
on new
ideas or
resource-
axially
through the
rear head and
middle
section
fulness.
into the chamber of
:he
front
head
to
form a
cylin-
drical
housing
for the
control rod
and a
return
passage
for
the
fluid
during
counterrecoil.
The
L. THE PUTEAUX.
MECHANISM
bore may be grooved longitudinally
for
flow
40.
The
Puteaux mechanism in Figure 8 illus-
control.
trates
a hydropneumatic, dependent
type
of recoil 42.
The control rod
is tapered and passes
through
mechanism.
It
consists of
a
hydraulic
brake, the
orifice.
At
its
forward
end,
it is
attached to,
and
directly
connected
by a port
to
the recuperator, centered
by,
a diaphragm. The breech end
of
the
which also houses
the controls. The
recoil
brake
control
rod is centered in its housing by a piston
DIRECTION
OF
RECOIL
BRAKE CYLINDER
GUN
RESPIRATOR DIAPHRAGM
SPRING
I-RECOIL
PISTON DIAPRAGMDIA STUFFING
BOX
777.
RNTO
W COUNTER-
TING RECOIL
CONTROL ROD
L- RECUPERATOR
ORIFICE
INDEX-----RNGULAROR
TAPERED CONTROL ROD ONE WAY
VALVE
REGULATOR
10
OIL DIRECTION
DURING
RECOIL
----
4
OIL
DIRECTION DURING COUNTERRECOIL
Figure
8. The
Puteaux Mechanism (Schematic)
10
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rwhich provides restriction
to fluid flow during ever,
in this
directon, the
ffuid
takes a different
counterrecoil when that
feature is desired.
The path. The
one-way
valves
in the regulator head
control
rod
is drilled
through
its
entire
length
to
are
closed and
the
fluid is diverted
to
the center
bore
accommodate
the fluid gage (index)
actuating rod. of
the regulator where it
flows
along
the control
43. The
floating
piston
separates
the gas
from
rod.
To
preclude excessivecountcrrecoil
velocities,
the
liquid
and
also indicates the volume of fluid the
flow is
usually
restricted atthe breech
end
of
in
the system.
It lies directly
in
front
of the dia-
the control
rod,
either by
slots
in
the
control
rod
phragm,
separated
from
it
by a compression
spring,
piston
or
grooves
in
the wall of
the regulator
bore.
The
spring insures
proper positioning
of
the
con- This
restriction
to flow is
sometimes construed
as
trol
rod just
before
recoil starts, as
it forces the
buffing
over
the
entire counterrecoil
stroke, but
diaphragm against the
orifice
plate. The
volume would
better
be considered
as
a
way to restrict
of fluid
between
the piston
and diaphragm is
the
the maximum counterrecoil
velocity.
fluid
reserve.
A
slender
rod, attached
to
the
piston,
48.
The
Puteaux recoil
mechanism
has these
extends
through
the
hollow
throttling
rod
to actuate
particular
advantages:
the
fluid gage.
Thus, the position
of
the
piston
a.
Compactness.
indicates the
amount
of liquid
in
reserve.
b.
Light
weight.
44.
The above
description
does not
include
any
c.
Provision
for a
fluid
index.
reference
to a
counterrecoil
buffer because
the
d. One
rod connection
to the
breech
lug
buffer
arrangement
has no bearing on the
identi-
or
to
the
front
end
of
the cradle.
fication
of the Puteaux
mechanism.
For
light
ar-
49. It also
has these
characteristic
disadvantages:
tillery,
where the
energy
to
be absorbed
is small,
a. Inadequate
fluid
reserve
may
allow
the
a buffer
may
be built
into
the
front end
of
the recoil
gun
to fall out of battery
at
high eleva-
cylinder.
For
heavy
artillery,
separate
buffers may
tion.
be
necessary to
insure
adequate
performance.
b. Control
rod is
not
positively tied
to the
45. During the
recoil stroke,
the
retarding
force
gun,
therefore its correct
position
is
no t
is created
by
pressure
built
up
on the
rod end of
inherently
assured.
the recoil
piston.
The
piston forces
fluid
to
flow
c.
Repairs
require
special facilities
and ex-
into
the
regulator,
where
it
opens
the
one-way
pert mechanics.
valves
and
contiaues
on
its way
through
the
orifice.
The
fluid
forces
the
diaphragm
and
floating
piston
forward
against
the
recuperator
gas
pressure.
As
F. THE
SCHNEIDER
MECHAMSM
the
diaphragm
moves
forward,
it
draws
the
throt-
50.
The Schneider
mechanism
(Fig.
9) illustrates
tling rod
through
the
orifice
and,
because
of
the
a
hydropneumatic,
independent
type
recoil
mechan-
proper
taper of
the
rod, adjusts
the net
orifice
to
ism.
It comprises
a recoil
cylinder,
a counterrecoil
the desired
area
at
each
increment
of stroke.
The
cylinder,
a
recuperator,
and a
built-in
buffer.
energy of
recoil
is
principally
absorbed
by throttling
There
is
no communicating
passage
between
recoil
through
the orifice.
Some
is stored
in compressing
cylinder
and
either
counterrecoil
cylinder
or
recu-
the
gas
and
a small
amount is consumed
in over-
perator.
All
controls
are contained
in
the
recoil
cyl-
coming
the combined
friction
of
all moving
parts.
inder;
the counterrecoil
cylinder
and recupcrator
46. At
the
very
start
of
recoil,
the
diaphragm
is
simply
store
energy.
The
recoil
and counterrccoil
pressed
against
the
orifice
plate
and
no
flow
can
piston rods
are
separately
attached
to
the cradle
occur.
This n.eans
that,
for
a brief
instant,
the
and
are stationary.
All threecylinders
are mounted
resistance
is
provided
only
by the
recuperator
gas
on,
and
move
with,
the recoiling
parts.
pressure
and
almost
no control
exists
over
the
51.
The
recoil brake
consist.%
of
three concentric
hydraulic
pressure
curve.
As soon
as an
appreciable
components:
the
outside
cylinder,
the
recoil piston
recoil
velocity
is attained,
the
orifice
is
regulated
and hollos%
piston
rod,
and
the centra
contro ro6.
to produce
the
desired
resistance.
52. The
control
rod is
rigidlN
attaiched
to the
47.
As recoil
ends and
counterrecoil
begins.
the cylinder and. therefore,
alo
mose,
%itth
the
rcc(1-
flow
of fluid
reverses.
The gas
pressure
pushes
the
ing
parts.
It extend,
:hrougt"
the
or:fice
and
int,
floating
piston
toward
its
original
position.
thus
the
hollo%
pitor
rod.
Its
contour
i,.
kucl-
that
it
forcing
the fluid
back
through
the orifice.
Ho%%-
properly
regulate-
lh
uritize
a,
it pa;ses
through
it
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COMPRESSED
GAS
RECU
PERATOR
_
COUNTERRECOIL
CYLINDER
LCOUNTERRECOIL
PISTON
RECOIL
COIL
----
PISTON
ROD
RECOIL
PISO
-ORFC
-
BUFFER-_.
"- "PISTONON-AREOLCIDR
CRADLE
VALVE
CONTROL RO D
DIRECTION
OF
RECOIL
Figure
9. The Scueider
Recoil Mchahioso
and
also permits
clearance
inside the hollow
rod placed
on the pressure side
of the piston is much
for free flow
of
the fluid.
greater
in
volume
than
the void
created
by
the with-
53. The
buffer consists of a
piston at the breech
drawal
of
the
control rod. Consequently,
enough
end of
the control
rod. It slides a
short distance
on fluid is available
to
control
the
pressure as
it
is
a
spindle
and thereby acts
as a one-way
valve,
forced through the
orifice.
During recoil, pressure
forces it away
from the end
56.
The
space
from iwhich
the control
rod has
of the
control rod and uncovers the
ports, allow- been displaced is readily
filled
with
fluid through
ing free flow to
the void created by the
withdrawal
the one-way
valve, which
is open
during recoil.
of
the
control rod. During
counterrecoil
the
valve
However,
when recoil ceases
and
counterrecoil
is forced
shut
and
the
flow
must be bypassed
begins, the valve closes and
the
fluid
is forced be-
around
the buffer
piston.
The
bore
of the hollow tween
the buffer piston
and the wall
of
the
hollow
piston
rod is slightly
conical for the last part of the
piston
rod.
Buffing occurs,
then, over the
entire
counterrecoil
stroke,
which
further
restricts
the
counterrecoil
stroke, and
the moving
parts are
flow
and provides the necessary
buffing
force,
finally brought to rest by the narrowing of the
54. Fluid
movement
is not impeded
except by restriction
described
in Paragraph
53.
gas
pressure
between the
counterrecoil cylinder
and 57. The
Schneider
recoil
mechanism
has
these
the recuperator,
as
no
control
is
attempted
in these
merits:
units. The recuperator
is of
the direct
contact a. It
provides
adequate counterrecoil
buff-
type with
no floating
piston between gas
and
liquid.
ing.
55. While
in battery position,
all
compartments
b. No floating
piston
is
used.
of the
recoil brake cylinder
are
filled with
fluid. c. The
control rod
is
secured to
the gun,
During
recoil, the control
rod is withdrawn
from
insuring
correct position.
the
piston rod
while the piston
rod moves out of
d.
Maintenance
in
the
field
is
rel,'tively.,
the cylinder,
each
motion
enlarging
the
volume
of
simple because assembly
and
disassem-
its respective
compartment. The
fluid
which
is dis-
bly
are
readily
accomplished.
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58. It
has
the following
drawbacks:
a.
Variable
recoil, to
suit
all
angles
of
a.
The recoil
and
counterrecoil
cylinders
elevation,
is
provided.
require
separate
filling.
b.
Adequate
counterrecoil
buffing
is pro-
b.
No fluid
index
is
included.
vided.
c.
A
fluid index is proviaed.
G64.
The
special
disadvantages
are:
G. HE LLUX:HA~SMa.
Inadequate fluid reserw,.
may permit the
59,
The
Filloux recoil
mechanism (Fig. 10)
is an
gun tc fall
out of battery
at
high
ele-
example of
the
hydropneumatic,
independent
type,
vation.
incorporating
variable
recoil,
It comprises
a
recoil
b.
Repairs require
special facilities and
brake
and
an entirely
separate
counterrecool
cy indcr
expert mechanics.
with attached
recuperator.
c. The recoil
and
counterrecoil
cylinders
60, The
recoil
brake
cylinder
contains the recoil
require separate filling.
piston,
a
hollow
piston
rod, a control
rod, and
a
buffer.
It is
similar
in some
respects to
the Schnei-
der
mechanism,
The
piston
has
two
ports,
1800
H.
THE
ST.
CHAMO.D
MECHANISM
apart,
leading
from
the pressure
side
to
the inside
65.
The
St.
Chamond
mechanism. Figure
II, is a
of
the hollow piston
rod
and
to
the tapered
throt-
hydropneumatic
dependent recoil
mechanism, rea-
tling grooves
in
the
control rod.
In this case,
the turing
variable
recoil.
It comprises a recoil
cylin-
control
red
does not taper but instead
there
are der, a
recuperator with
floating piston, and
an
two
pairs
of
longitudinal
throttling
grooves.
One independent
buffer assembly. The recoil cylinder
pair
is
short
and
regulates
the fluid flow
for high and
recuperator are interconnected.
angles
of elevation.
At high
elevation,
stability
66.
During recoil,
the flow
of fluid
from the
of the weapon
is not a
serious
problem,
but ground
recoil
cylinder
to the recuperator
is regulated
by
a
clearance
for
the
recoiling
parts
very
often
is. spring
loaded throttling
valve located
between
Therefore,
a short
recoil stroke with
relatively high
them. Variable recoil
is obtained by
alteiing the
force may
be advantageous.
At
low
angles
of limit of valve
opening. The pressure
which
pro-
elevation,
the
situation
is reversed and
a long stroke
duces the
retarding
force
is determiaed
by
the
with smaller
force
is desirable.
This latter
is
ac-
amount
of valve
opening and
the recoil
velocity.
complished by bringing into
play, additionally,
the
67.
During
counterrecoil the
one-way
counter-
other
pair of
throttling
grooves
which
are
long.
recoil valve
opens and
fluid flows
back
to
the
recoil
The
control
rod
can
be
rotated
so that only
the short
cylinder
by
this path. In
the
last part
of
the
stroke
grooves, or both
long
and
short,
or a continuous
the parts
are
brought to
rest
by an
externa
dashpot
graduation
in between,
are exposed to
the
discharge
buffer.
from the
ports
in
the piston,
This rotation
is
68. The
desirable
features
of the St.
Chamond
accomplished
directly and
positively
from
the
ele-
mechanism
are:
vating
motion
by a
cam and
gear arrangement.
a.
Variable
recoil
is
provided
at
all eleva.
61.
No attempt
at throttling
during
counterrecoil
tions.
is
made in
the
recoil
cylinder,
except
for buffing
b.
It i: compact.
during
the final
part
of
the stroke.
Instead,
a
c. It
i* lhht
in weight.
regulator
vaive,
located
in
the recuperator,
re-
69.
The
undesirable
features
are:
stricts
fluid
flow
in
counterrecoil.
The
recuperator
a.
An
inadequate
fluid
supply
may
permit
is
of the floating
piston
type,
where
gas and
liquid
the gun
to
fall
out
of battery
at
high
are
separated.
elevation.
62. The
operation
of this reccil
mechanism
is
b. No
fluid
index
is provided.
characteristic
of hylropneumatic
systems
and
need
c. Repairs
require special
facilities and
ex-
not
be
repeated here. Finally,
cuunterrecoil
buff-
pert mechanics.
ing
is
accomplished
by
a spear
buffer
located
in
the
recoil
cylinder.
63,
The
peculiar
advantages
of
the
Filloux
mech-
1.
DOUBLE
RECOIL
SYSTE.M
anism are:
70.
All
mechanisms
heretofore
discussed
are
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single
recoil
systems. Sometimes,
particularly
with
and independent
systems,
or upon
the
type
of
heavy
weapons,
it
is advantageous
to introduce
a
buffer selected.
secondary
recoil
system
between top
and
bottom
76.
Another
requisite of
extreme importance
is
carriages.
Double
recoil systems are
discussed
in
ease of
maintenance.
Ability to be
repaired in the
detail
beginning with Paragraph
147.
field
is
a prime
asset. Ruggedness
and durability
should
be intrinsic
in
the design,
so that
ordinary
wear
and
tear may
be withstood
for
long
periods
of
VI.
SELECTION
OF A RECOIL
SYSTEM
time without
overhaul.
When maintenance
work
does
become
necessary,
it
will
be greatly
eased
by
simplicity
in
the mechanism.
A minimum
number
A.
GENERAL
of
parts
facilitates
disassembly
and
replacement.
71.
Selection
of
the
type
of
recoil
system
is Special
techniques should be
eliminated
so
that
governed
by the characteristics
of
the weapon, such
mechanics,
with
only
ordinary skills,
can
make
as size, purpose,
rate of
fire,
and range
of elevation
repairs merely
by following
instructions.
Damaged
angles.
Hydrospring
systems are
usually
limited to
parts
of
one
unit should
be replaceable
by service-
light artillery
and
short recoil
distances.
Hydro- able
ones from
disabled
weapons.
The advantages
pneumatic
systems can
be
adapted to either
Lght
or of using
standard
and commercially
available
parts
heavyartillery.
Heavy mobile
weapons may require
cannot be
overemphasized.
They
cost
less, are
double
recoil systems.
readily
procurable,
and
can
be made
in less time
72.
The
options
as
to
whether
the
mechanism
than
special
parts.
shall
be
independent
or
dependent,
variable
or
constant
recoil stroke,
floating
piston
or
direct
contact, internal
or
external
buffer, all are strongly
VII. PRELIMINARY
DESIGN DATA
influenced
by
basic
factors
such
as recoil
force
and
distance,
space
available, stability,
and ground
clearance.
The
foregoing
discussion
of
several
A.
VELOCITY
OF
FReEE
RECOIL
designs,
and their
merits
and shortcomings,
is in-
77. The
original design
data
required
for the
tended as
a guide
for future
determinations,
recoil
mechanism
are
the length
of recoil
and
the
recoil
force.
These
items are
interdependent
and
their
values are
based
on
the
momentum
of
the
8.
REQUISITES
OF THE RECOIL SYSTEM
recoiling
parts and the
combined
momentum of
73.
A
long
recoil
stroke is usually
desirable
to
projectile
and propellant
charge.
Preliminary
minimize
recoil
forces. However,
the length
of figures
for
recoil force
and length
of
stroke
are
stroke
may
be
limited
by ground
clearance,
espe- based
on the
velocity
of free
recoil,
which is de-
cially
at
high angles
of
elevation. At
low
elevations,
termined
from the
momentum:*
where
stability is critical,
clearance
is available
for a
longer stroke.
This
suggests the use
of variable.
*v,
+
4700W.
(2)
recoil
or double
recoil.
W,
74.
The recoil
distance
is also
influenced
by
a
where: v
maximum
velocity
of free
recoil,
high
rate
of
fire.
The
recoil
cycle
must
be
com-
f
tx
v
yf,
pleted
quickly
to be ready
for
the
next
round.
It
v
muzzle
velocity
of
projectile,
ftlsec,
may be
necessary
to
shorten the stroke
and
design
=
weight
of
propellant
charge,
lb,
the
structure
to
withstand
the higher
forces
which
W, =
weight of
projectile,
lb,
result.
A rapid
counterrecoil stroke
requires
a large
W == weight
of recoiling parts,
lb.
energy
storage
in the recuperator.
Even more
critical
is the large
buffer
force required.
Free
recoil
defines
the condition
where no
resis-
75. The
most important
single
factor having
the
tance is offered
to the recoiling
parts.
The value
greatest
influence
on the
selection of the
recoil of
4700
feet per
second is
the assumed
velocity at
system is
the
space
available.
This
may dictate
which
the propellant
gases
leave
the
muzzle. It
is
the
use
of
a hydrospring
mechanism
instead
of
Page
242
of
reference
I.
References
are
found
at
the
hydropneumatic,
or
the
choice
between
dependent
end
of
this
handbook.
16
nn I II I I I l II i
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. an empirical value based
on
firing tests.
This ponent
W,
si, M,
d2x
changes directions. The
formula
is approximate but is sufficiently accurate
on
for
its
intended application. If desired, more
exact value of K in Equation
(3)
is eventually de-
accurate methods are available
in texts on termined by
trial
through a step-by-step
integration
ballistics.
(see Chapter IX, Part C) but, first, a reasonably
close value must be
found to
put it
in
the working
range. The
energy of
free recoil
and the
length
of
.
RtECDL
FOE
recoil are
used
for this purpose.
78. The
general
equation for the
forces
acting on E, -
*M, Vf
2
, 3a )
the
recoiling
parts
is:
where: F,
-
kinetic energy
of free recoil,
F# + W,
sin*
- K -
(3)
M, - mass of the
recoiling parts,
v
-
maximum
veloity
of
free
recoil
where: F,
-
propellant
gas
force, (Eq.
2).
K -
total resistance to recoil, This energy,
divided by
the length
of
recoil, gives
M, -
mass of
recoiling parts,
the average resistance necessary to
stop the
moving
W,
weight of
recoiling parts,
mass. To this resistance must be added the static
I - time
of
recoil, force
component
of
the weight of
recoiling
parts
x
-
length
of
recoil
at
time t,
(W, sin#). The first approximation
of the total
0 - angle
of
elevation. resistance to recoil
is:
Figure
12 illustrates this force system.
The
expres-
d2x K
i, + W,
sin#, (3b)
sion
M,
&, according
to D'Alembert's principle,
L
represents
the inertia force. The propellant
gas
where:
L
-
length of recoil,
force soon
becomes zero and, since K
always op- 0 - angle of
elevation.
poses recoil and is greater than the weight cor-
Although the
recoil
rod
force, KR, is
reduced some-
what from K by
the
frictional
forces of
the
cradle,
K, as defined in
Equation (3), will
be
used without
modification as
a
preliminary
design load for
the
recoil mechanism. The error involved
will
be
small and conservative. For
final design, these
frictional forces may
be c