Carriages and Mounts Series

8/9/2019 Carriages and Mounts Series

1/92

UNCLASSIFIED

AD NUMBER

AD830281

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LIMITATION CHANGE

TO

Approved for public release,

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Distribution

authorized to U.S.

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and

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Administrative/Operational

use; Sep 1963.

Other requests shall be

referred

to

Army

Materiel Command,

Attn:

AMCRD-TV,

Washington

DC

20315

AUTHORITY

USAMC ltr,

22

Jul

1971

THIS

PAGE IS UNCLASSIFIED


2/92

#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


3/92

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.


4/92

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


5/92

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


6/92

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


7/92

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


8/92

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


9/92

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


10/92

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-


11/92

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


12/92

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


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


14/92

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


15/92

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


16/92

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


17/92


18/92

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


19/92

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


20/92

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

I0


21/92

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

II


22/92

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.

12


23/92

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

13


24/92

ata

IxI

at

cc

ug

w0

zz

00

-3AOO

-

I.z

0

z Iz

00

14~


25/92

II

ILI

-i

>

0X

ILI.

9

ji0

0

7j

w


26/92

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

iI


27/92

. 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

Carriages and Mounts Series

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