cylinders; hydraulic brake, master, power assisted

MIL-C-7979B

21 OCI’OBER 1959

SUPERSEDINGMIL-C-7979A2s JULY 1956

MILITARY SPECIFICATION

CYLINDERS; HYDRAULIC BRAKE, MASTER,

POWER ASSISTED

T/in Wm’jlcatim b beenapprovedbu t-hoDvurt-1 OfWUIW ad u Wn-&tmv for um bV thd Ddpurtmmt#of tha Armv, the Navv, and tho Air Force.

L SCOPE

1.1 This specifmntion covers hydmulicpower rwsisted mneter brake cylindere de-signed for use in aircmft hydmulic wheelbrake subsystems which opemte at Oto 1,600pounds per squore inch pressure and oreused in nirplano hydmulic systems hnvingpower input pressure9 up to S,000 poundsper squnm inch.

2. Applicable DOCUMEh’TS

2.1 The following documents, of the issuein efTect on date of invitation for bids, fomr8 P8rt of this specification:

SPECIFICATIONS

hf ILITABY

MILP-5517 — PlesticPartsin Air-crn ft HydmulicEquipment; G en -eml Testsfor.

MU.-H4Y36 — Hydmulic Fluid,Pe-troleumBose,Air-cmft and Ord-mncc.

MIL-R-S534 —Brake Systems,\Vh ee1, Aircmf&Design of.

M.lL-H-S775 — HydraulicSystemCampenenh A ir-cmft, GeneralSpecitkotionfor.

STANDARDS

lfrLrTARY

B1IL-STD-105— Sampling Proceduresand Tables for In-;w&imr by Attri-

(tiPiCS of Swriflcations, standards, drmvingc., andpublicntlonn rquircd by contractors in connectionwith spcciflc pmmrmncnt functions shmld be ob-tnincd from the procuring activity or no directed bytha contractingOmc_.)

3. REQUIREMENTS

9.1 Preproduction ixunple.Prior to begin-

ning quantity production, prepmduction-Pke shall be subjected to prepmductiontesting. The prepmduction snmple shall beproduced by the snme method and of the

Downloaded from http://www.everyspec.com

MIL-C-7979B

same material that will be used for quantityproduction of the item.

3.2 (herd. The requirements of Specifi-cation MILH-6775 apply as requirementsof thk specification, with the exceptionsand

additions epecbied herein. When the two

apecifieations conflict, this epecifieation

shall govern. Unless otherwise epecifiedby

the procuring activity,the brake cylinders

ehallnot be used with any fluid other thanthat conforming to the requirements ofSpecification MIL-H-5606.

3.3 Design and construction.

3.3.1 The desiti of hydraulic power assist-ed master brake cylindere shall include thefollowing:

(a) A mechanically actuated pressuregenerator.

(b) A control unit whereby fluid underpressure ie used to boegt the out-put of <the pressure generatorand provides input force reac-tion” (load-feel).

(c) A common communication line withthe reservoir for the pressuregenerator and the power systemreturn fluid.

3.3.1.1 The above features, where practi-cal, ehall be combined into one unit operableby the pilot’e brake pedal. A euitable meansfor attaching the brake cylinder to the air-plane etructure and the operating linkageehall be included in the design. See. figure 1.

3.3.2 Inpttt pressure. The imit shall be di-sigrred for an input pressure of 3,000 poundsper square inch.

3.3.3 Output pre9eftres. Output pressures

shallbe those “power on” and “power off”

brake operating pressures which are re-

quired by the specificbrake system being

eoneidered.

3.3.4 Booet ratio. The ratio of the outputpressure generated by a given actuatingforce’ with power on, to the output pressuregenerated by the came given actuating forcewith power off, shall be known aa the boostratio of the unit, and the boost ratio shall besuch that the required output preasurex canbe generated.

3.3.5 Structural 8treagth. The operationofthe brake cylindershallnot be impaired,

and no partoftheunitoritsmountingsshallgiveevidenceof failureunder the limitap-pliedmechanicaloperatingforcesfora given

airplane installationor for the wrench-terqueloadsrequiredformaking the neces-sary connections.

3.3.6 Power amid cutoff. Power aeeietshall ceaee when the power-en output pres-sure reachee a predetermined value as gov-erned by the specific requirements of thebrake system being considered (see fig-ure 2).

3.3.7 Brake line output. Meana shall beprovided for limiting the output pressure ofthe brake cylinder with power on, to a valueof the brake burst pressure divided by 1.67(see figure 2). The force which shall be ap-plied to the unit for determining the limihing output pressure shall be that whkh cor-responds to the limit applied force at thebrake pedal aa defined in Specification MIL-M5EM.

3.3.8 L31eedin~. Provisions shall be made inthe design of the brake cylinder such that,with no mechanical force applied te the pres-sure generator, any entrapped air can bebled from the unit. This may be accomplish-ed by proper internal design and does notnecessarily require an external bleed port.A power bleeding feature whereby fluid fromthe pressure port can pass through the unitof the brake port is also required.

,’

4

2


MIL-G7979B

\

.-. .

d\cKfENTSTRUC’NRE

I

. m“y-i? (OIJTPUT)

rrs’

KI

F

POINT OF ATTACRJ4EtJT~ATR?LANE BRAKE PEOALLINKAGE FOR APPLICATIONOF ACTUATING FORCEF

O.,:,,.=A.?

s


9&o

5% 15!

.rLIMITBRAKS

PFJ2

SSU

RE

=‘-

‘~;

‘-.

——

-—

——

-..-

—--

--—

-—--

-

PO

~O

NC

UR

VR

FOR

TY

PEr

LIM

ITA

PPL

IEO

PE

DA

LFU

RC

E[

OF

UN

TT

USI

NO

PRSS

SUR

E(R

EF

ER

ASE

SYST

SMSP

EC

IFI-

,

CH

AM

BF.

RRE

LIE

FV

AL

VE

mC

AT

ION

)

PNSV

EN

’IO

VE

RPR

ESS

UR

Iffi

UN

IT7

I J}

~F.c

EA

TW

HIC

H

PRE

SSU

RE

GE

NE

RA

TIO

NB

FWK

EST

RFN

GT

R

I I/’

II

m

Im

xmm

wm

ON

1,

IP

OW

lO

NO

UT

PU

TPR

F5SU

RE

I

IC

UR

VS

I.f

I/

I I I I(’

I~

AU

OW

~L

EPm

AL

FuR

CE

FOR

IPO

WER

-OFF

ouTP

uTPR

Essm

II

RD2UIRFMENT.

(REFBRASS

‘“

,

20

BR

AK

EA

CT

UA

TIN

GFO

RC

EA

Pm

xoA

TB

RA

mm

DA

Lm

mum

s(F

OR

AC

ON

STA

mw

PEO

AL

TO

CT

LI~

Rm

cmm

cfi

AD

VA

NT

Am

syrt

o)

Fmuun2.T@cul

pcrf

otm

ance

cum

eafo

ra

hudm

ulio

PO

WWa

wia

tedm

asta

r%qI

NaI

&T

..

●

ON

CU

RV

EAF

TE

RA

SSIS

TC

UT

OFF

NO

TE:

THIS

ISA

NE

XM

FLE

ON

LY

AN

DIS

NO

Tm

BE

CO

NST

RU

ED

ASINDICATINGANY

PARTICULARACTUAL

REQuIB124~TS.


@

.,.

.

c)-’=

.*

@.J....*

3.3.9 ReturiI mechuniem. A mems shall beprwvidedwithintheunittoreturnthepres-mcrogenerotorto ite relaxed position uponrelease of the actuating force. The returnrate shall be sufficiently mpid to provide npressure drop in the unit, enough greeterthan that in the brake system, to assure nbuildup to the required pressure within therequired number of pumping strokes whentested os specified in 4.6.7.

3.3.10 Pt/mpinfl. The control unit shall bedesigned to permit “pumping up” of the hy-draulic pressure inn broke system where thecontrol unit travel to opernte the brake maybecome greater thmr the tmvel normally re-quired, such es in the cnse of n Iohking Pmlc-ing in the unit, n leak in the brake system,or increase in broke clearance due to wear.It shall also serve to fncilitete blwding ofair fmm the system and rnnintaining an air-fme system. The pumping vrdve shall remainsealed at all timss during the opemtingstmka and shall bo designed te open im-mediately at any time when the bmkc linehydraulic pressure may beceme npprecinblyless than the reservoir pressure. Pressuretmp through the vnlve during pumping shrillbe autliciently low to nseure compliance withthe pumping test spwifled in 4.6.7.

3.3.11 Opcratien tcmpemtures. The brokecylinder ehnll be designed nnd constructedfor opemtion at n temperature of from -66°to +160”F.

3.4 Performance. The broke cylinder shallsatisfy the performance requirements .9pwi-tled in atilon 4 when subjected to the testshendcd ea follows:

(a) Immersion of plastic ports (4.6.2).

(b) Static lcnkoge (4.6.8).

(c) proof pressure and Ieakngc (4.6.4).

(d) Sustained force function(4.6.5).

(e) Power cutoff(4.6.6).

(f) Pumping function(4.6.7).

MIIX-7979B

(K) Through bleeding(4.6.9).

(h) Extreme tompemtnre (4.6.10).

(i) Endumncc (4.6.11).

(j) Efficiency(4.6.12).

(k) Boostmtio (4.6.13).

(1) Burstpressure (4.6.14).

3.5 Marking. Afl ports sbcdl bs clearly andpermanently marked to indicate the properconnection to be made.

4. QUALITY ASSURAh’CE PROVIS1ONS

4.1 Unless otherwfse specified herein, theeupplier is responsible for the performanceof all inspection requirements prior to sub-mission for Government inspection and nc-ceptnnce. Except es otherwise specified, theeupplier may utilize his own facilities or anymunrnercial Iabomtary acceptable tn the Gov-ernment. Inspection recerds of the exarnim-tions mrd tests shall be kept complete andnvnilable to the Government es epecifmd inthe contmct or order.

4.1.1 General. The qunlity assurance pro-visions of Specification MIL-H-3776 shall

Vpb’ as qunlity ea9umnce provisions Of thisspcciflcation, with the exceptions and addi-tions spmifled herain. When the two apeci-tlcatione conflict, this specification shall gov.em.

4.1.2 Cfaam”~ation of teats. The inspectionnnd testing of the brake cylinders shall beclaeeitlod os follows:

(8) Pmpreduction t+sta (ace 42).

(b) Acceptnncotests(ace4.3).

4.2Preproductkmtests.

4.2.1Sampling instructions. The prepro-duction sample(s) ehdl consist of the fol-lowing broke cylinders and shall be testedin a place and manner designated in the con-

6


MILG7979B

ha+ purchaeeorder,or invitationforbide(see6.2.1).

(a) One test unit shall be made withcritical tlte wif.hii 10 percent ofthe maximum allowed clearancese specified by the detail drawingtolerances This unit shall be usedfor endurance and noqnal tem-perature ftintilonel tests.

(b) A second unit shell be made withcritical fits within 10 percent ofthe minimum allowed clearancese specitled by the detail drawing.t.olerancee. Thie eecond unit shallbe used for extreme temperaturePreproduction teata.

4.2.2 Teatu. The P+eproduction teata ofbrake cylinders ehell consist of all the testsof this specification, as described under“Test methods” (4,6).

4.9 Acceptance teata. The Acceptance t..satashall consist of Individual tests and Sam:pling teata.

4.2.1 Individcd teats. Each hydraulicpewer assisted master brake cylinder shallbe subjected ta the following tests in theorder specified herein:

(a) Examination of product (4.6.1).

(b) Static leakage (4.6.2).

(c) Proof pressure and leakage (4.6.4).

(d) .%cetaiued force function (4.6.5).

.(e) Power cutoff (4.6.6).

(f) Pumping function (4,6,’7).

(g) Operation (4.6.8).

4.2.2 Sampling teds. SSrnple brake cylin-ders shall be selected from each inepti]onlot in accordance with Standard MIL4TD–105 at inspection level II; using an acceptableqtility level (AQL) of LO percent defectivefor the following teete described under “Teatmethods” (4.6):.

6

(a)

(b)

(c)

(d)

(e)

(f)

(e)

(h)

Immersion of plastic parte (4.6.2). ●Through bleeding (4.6.9) .

Extreme temperature (4.6.10).

Endurance (4.6.l.1).

Efficiency (4.6.12).

Boost ratio (4.6.13).

Burst pressure (4.6.14).

Packing and marking (4.6.15).

4.3.3 Rejedion and retest.

4.2.3.1 Preproduction teat faikme. Thefailure of any Preprodu&lon test unit sub-jected to the teste es the first unit of a newdesign shall be cause for rejection of thedesign represented. The acceptance of theremaining brake cylinders on a contract orpurchase order shall be dependent u~n approval of the test reeulta on the Preproduc-tion sample required by 4.2.2.

4.3.3.2 Acceptance test failure. Rejectedlote may be reeub~itted in accordance withthe paragraph titled “Resubmitted lote” ofStandard MIL-STD-105. A resubmitted lotshall be inspected using tightened inspection.Before resubmitting, full particulars con-cerning the previous rejection and the actiontaken to correct the defeda found in the ori-ginal unite shall be furnished to the inepee-tor. The uniti reject6d after retest shall notbe resubmitted without the specitic approvalof the procuring activity.

4.3.3.3 ,In.spectien M. For purposes of in-spection eampling, an ineptilon lot shall beall brake cylinders msnufachmad under thesame conditions and offered for inspectionat one time.

4.4 Report of teeta. A report, tn duplicate,ehowing the quantitative results for afl theteeta required by t.lis speciclcation, shell besubmitted to the procuring activity.

.

●

*

●


@.- 4.5 T~t conditions.

4.5.I Tat fluidn. The hydmulicfluidueodfor all the teats shall conform to the require-ment of SpecificationMIL-H-5606,exceptaeotherwises~ifh?dherein.Allentrnppodairmustbebled fmm the brake cylinder andthe unit Palled with the fluid before conduct-ing any teeb of tlik speciftcntion.

4.5.2 Temperature. Unlcaeotherwisespec-ified,thetee~ehallbe conductedwith theoilata mom temperatureof70° tollO°F.The actualtemperatureduringthePrepm-ductiontasteshallbe reported.

4.5.3 Preeeure. Opemting prea9uresforalltestsshellbe%000 pounde per square inchinput pressure and those output preseumewhich nre required by the particular brakeinstallation for which the broke cylinderwill be Ueed.

4.6 Teef metheda.

4.6.1 Examination of product. Each brakecylinder shell be cnrcfully examined to d-termine conformance to the requimrnente ofthis specification with mepect to mnteriete,workmenehip, end marking, and for mn-formence with the limiting dimensions indi-cated on the applicable manufacturer% dmw-i43a.

4.6.2 Immersion of pfaatk parta. Brakecylinders containing plnetic parta shall beeubjected to, and meet the test requirementsof SPecMcntion nfI~P-5517. Theee tect9shallbe conducted prior to all other tests forfir-et articlea unleee these tests are specificol-Iy waived by the procuring activity on thebasis thnt the plastic material used has beenpreviously appmvcd in similar umge.

4.6.3 Static leakage. With the brake cyl-inder in the normally installed and full offpoaitiona, apply 2-psi preaeure to all internalfluid snacea. For m-enmdu&lon units. the

6!9preeeu& ahrdl be ~ppfiod for 2 bouraj nnd

..4?

MILG7979B

tide.arrternalleakage elm]] not exceed 1 dropper hour. For individual units, the preeeumshall be applied for 10 minutes, ,and no ex-ternal Ienkage shall occur in that tiie.

4.6.4 ‘Proof premure and leakage.

4.6.4.1 Preeeeme pert. With the brake cyl-inder in the full off poeition, 25 psi andthen 1.5 times the input pressure ehall beapplied to the preeeure port with the brakeand return pate open. The internal leakageehall not exeeed 2 drops per minute afterthe tlret minute at the 26-psi preseure and80 drops per minute after the ftret minuteat pressure equal to 1.5 timee the inputpressure. Each presmre shell be applied for

n Perled of 3 minutes. There shall be no ex.ternal leakage at either preeeure.

4.6.4.2 Bmko port. The brake cylindershall be mounted in ita normal operatingposition, and the piston shall be cmureetedto n manual etop to retain it in the mid-trevel poeition. The eide of the pressure gen-emtor opposite the brake pm-t shall be open-ed to the atmosphere. A preaaure of 10 psishall be applied to the brake pert for 9 @-utca, followed by the application of a pres-sure of .l.S time9 the maximum power onoutput preeeure for 3 minutes. No externalleakage shall be allowed. After 1 minute, tholeakage at the open ports shall not exceed2 drops per minute at either preseure. Whenthe cylinder ie permitted to return completelyto the off position, the valve peaaages shellpermit flow fmm the brake pmt out the Bturn port. This test ehell be repeated 9 timesfor Preprodu&lon tests only.

4.6.4.3 Return port. With the brake cyl-inder at the fully actuated position and thebrake and pressure ports open, apply 25 peiand then 1.6 tirnee the maximum power onoutput pree9ure to the return port. Thereshall be no external leakage in 2 minutec ateither preeeure.

4.6.4.4 Hamees. ‘l’ha brake cylinder &all

7


MILC-7979B

be..mounted in a position and test fixturewhich simulates its actual operating condi-tion, and the brake port shall be connecteddirectly to a hydraulic-pressure gage. Apressure source of 1.5 times the input pres-sure shall be applied to the pressure port.A mechanical force equal to the force result-ing from a 300-pound brake pedal force for

a given ainlane installation shall then beapplied to the unit while it is in the mid-travel position and held for a period of 5minutes. A lever system and weights maybe used to apply the force to the unit. Thistest shall be repeated allowing for escape offluid, from the pressure generator section inorder that the test load is npplied when theactuating ehrtft is at a position representing75 percent of the stroke. There shall be noexternal leakage. permanent distortion, fail-ure, or malfunctioning of any part of theunit.

4.6.5 Sustained force function. The brakeport shall be connected to a gage, and inputpressure shall be applied to the.pressure portwith the return port connected te the re-servoir. The pressure generator shall then beloaded at approximately the midtravel posi-tion u$ing an operating lever and weightsllhe.operating lever weights shall corresponrlto 25 percent followed by 100 percent of the pi-lot effort which correspond to the maximumpower-on output pressure. At each load, theoutput pressure shall be within &5 percentof the design maximum power-cm outputpressure. A elow fluctuation of the outputpressure is permissible. This fluctuation p;es-sure range shall not exceed 5 percent of thedesign maximum power-on output pressure.The leakage out the reservoir port duringthis test shall not exceed 2 cubic inches perminute after the first qinute, and the posi-tion of the piston shall remain unchanged.The duration of the test shall be 2 minutesat each of the 2-rod loads. When the leadis removed, all moving parta of the brakecylinder shall return to the full off pesition.The test shall be repeated twice fur the Pr&prediction tests.

4.6.6 Power cutofl. A test shalf be con-ducted te determine the output pressures ●developed with various actuating forces ap-plied to the brake cylinder. A curve shallthen be plotted to show that power assistceases at the maximum power-en outputpressure (see figure 2). For Individual testa,any means whereby the proper cutoff func-tion may be observed will be acceptable..

4.6.7 Pumping function. With zero psi atthe input pressure port, the reservoir returnport of the control unit shall be connectedto a supply reservoir and the brake port toa simulated brake consisting of a cylinderhaving a spring-loaded piston. Line lengths,

-, and sizes, together with reservoirhead pressure used (or intended to be ueed)in the airplane installation shall be simulatedin the test. The simulated brake shall re-quire a minimum hydraulic pressure of 30psi for initial movement of the piston, afterwhich pressure remction shall increase linear-ly with displacement, reaching at least 200psi after having been displaced by o volumeequivalent te 200 *1O percent of the mini- ●mum full displacement of the control unit.At that point it shall bettom. The controlunit shall fully displace the piston and reachpower-off operating pressure with 5 actuat-ing strokes, with hydraulic fluid and thecontrol unit at (a) 160° &5°F. an~ (b)-20° SC5”F. Rety-m .pf the unit to \te re-laxed position, preparatory to the next ump-

1ing stroke, shall be self-motivated. Th testshall be repeated with power system nputpressure supplied to the input pressure\pOrtof the control unit, in which case it Shallfully displace the pisten in the loading c’ -

3inder and reach power on operating pressur \within 5 actuating strokes. A schematic di-agram of (the test setup is shown in figure 3.

4.6.7.1 A qualitative type of pumping test

mcY be substituted in place. of the fore-going test for Individual tests only, in whichthe supply line configuration shall simulatethat of the airplane. The brake Port shall becapped while the control unit ~ held in ita

●8


fully actueted position. As the mntrol unitis cycled, a mpid deerease in the length ofsuccessive “pr-ure” strokes of the pistonshall be noted. Return of the piston, prepar-atory to the next pumping stroke, shell beeelf-motivnted. This test shall be conducted

mLFG7979B

with (a) zero pressure and (b) power sys-

tem input pressure at the input pressure

port, at n room tempemture of 50° to llO°F.

and with hydmulic fluid at a tempamture

of 70° to”190°F.

RLSJ2RVOIR

.._—

PuSITIVEOR NSOATXVSHSAD SIllULATING RRASS Lxm AND SUFTLYAIRPIMZ LINE IENOTSS, -,INSTALLATION P ANDSIZES TO SllfGLATS

L -AIRPLANEINSTAIJ

0

FUMESSYSTSH

SIHULATSDSRAfZ CONSISTI!J3OF CYLINDSRWITHSPRMO-

TSST CO)~ROLGRIT L@JISDPISTONWITH200 *lo FSRCSNTOYDISPLA~ OF TESTCOltTROLWIT

PUI&TYPS COMTRGL WIT SHOW IN THIS SCHMATICDIADRM.RNSR.SS mRTING FORFVSN-TYPSCOmfOJLWIT.

Fmrme 9. i%rnpkrgtit O#tUp

4.6.8 Qperation. Emlr brake cylinder shrillthen be subjected to an opemtion test withpower on. At one point in ench cycle of thistest, the maximum power on output pressureshall be nttained without exceeding the nct-ueting force required for the given instal-Ietion. External leakego nfter S5 such cycles

shall not exceed 1 drop. There shellbe noevidenceof chattering,vibration,or othermalfunction.

4.6.9Through bleeding. With the brokecylinder mounted in its norrrrel opemtingpcaition nnd mnneetcd to n lever system, in-

9


MIL-C-7979B

put pressure shell be applied at the pressureport, and the unit shall be operated to con-tact the stop at the end of travel of thepressure generator. A free and continuousflow shall occur out the brake port.

4.6.10 Eztrr.me temperature.

4.6.10.1 General. The brake cylinder hav-ing all critical fits within 10 percent of theminimum allowed clearances as specified bythe detail drawing tolerances shall be sub-jected to the extreme temperature teate asdescribed below. A tabulation of the actualmeasured dimensions of the critical matingparts, together with the limit dimeneiona

specified by the detail dmwinge, shell be in-cluded in the teet report. Transfer cylin-dere may be used to supply the volumes ofstabilized temperature input fluid requiredfor these teeta.

4.6.10.2 High temperature. The brake cyl-inder and ite operating fluid shall be corrtain-ed in a chamber having an ambient temper-ature of 160° -&5°F. for 24 hours. The teatcylinder shell then be subject6d to the testa.of this epecifieation entitled Pumping func-tion (4.5.7) and Sustained force function(4.6.5), and it shall satisfactorily pass thesetestx.

4.6.10.3 Low temperature. The brake CYI-inder and ite operating fluid shall be con-tained in a chamber having an ambient tem-perature of -65”F. maximum for 24 hours,during which time a fluid head of 2 psi shallbe applied to all the porta. There shell be noexternal leakage. The unit shall then be sub-jected to the teate of this specification entitledSustained force function (4.6.5). In addition,the action of the unit shall be observed forany indication of binding, and any function-ing different from that at normal temper-atures shall be reported.

4.6.10.4 Rapid warmup. The test chambershall be warmed rapidly from the -65”F.temperature to the + 160°F.temperature.

10

A record of the test chamber temperatureo

and the invut and outDut fluid temperatureshall be r&intained. Me teat entitled Sue-tained force function (4.6.5) shall be r-peated at 5-minute intervals during thewarmup, and the operation of the cylindershell be observed for any indication of bind-ing or functioning different fmm that atnormal temperatures. This teat may be endedafter the test chamber ambient temperaturehas been stabilized at 160”F. and the tem-perature of the input operating fluid, meas-nred at the cylinder, return port, has in-creased to 100°F.

4.6.11 Endurance, The brake cylinder shallbe teated for endurance ae follows:

(a)

(b)

(c)

(d)

(e)

The test cylinder having all criticalfits within 10 percent of the maxi-mum allowed clearances ee speci-fied by the detail drawing toler-ances shall be used for the En-durance test.

Prior to the text, the tact cylinder●

shall be hot-soaked for 7 da ye inthe applicable hydraulic fluid ata temperature of 160”F. if it eOn-tains packings not of the type or

glands not of the design whichcomplies with the requirements ofthe applicable listed specifica-tions.

The test cylinder shall be mountedin the teat fixture in iti normaloperating position.

Each cycling stroke shall be 90 per-cent miniinum of the total strokeof the pressure generator.

The maximum power-m outputpressure or a greater pressureshall be generated for 20,000cycles; and one half of the maxi.mum power-on output pres~ureshall be generated for an addi.tional 80,000 cycles.

r

●


(3.1

-.. , ~

(f) The unit ehoU pump 25 percent ofthe preaeure genemtor volumethrough n relief valve duringeach cycle.

(g) The movement of the unit duringthe return stroke of encb cycleahnll not be externally oeeisted.

(h) The rate of cycling shall be ae rapidae the teat condition wiU permit.

(i) PriortotheEnduranceteaknftcr20,000and 60,000Endumnce test

7 cycles,and at the conclusionoftheEndurancetact,the&et cyl-indershallbe subjectedto theteataofthisspccif?mtionentitledIndividualteata,and theresultsshallbe tabulated in detail in theteat report (4.4) .

(j) The test of this specification en-titled Boost ratio (4.6.19) ebdlbe performed prior to and at the

e

end of the Endurence teet.,~d

(k) The nctual dimension-e of the tcet

cylinder parta which undergorctative motion ehnll be recordedbefore and after the teet. Theeedbnensione, along with the dif-ference between the two diroen-sione (wear) and the limit dnen-eiona speciftcd by the detail dmw-inga, shell be tabutated in detailand inctuded in the test report(4.4).

(1) All pnrta of the tact cylinder“ ehall be incpccted before nnd

aftor the teet. A comparisonof the condition of the parta,@call then be made and in-cluded in the report.

4.6.12 EfficiencII.

4.6.12.1 Volumetric efficicnw (power off).The fluid displacement (power off) of thebrake cylinder efdl be meaeured by direct-

0~,= ing tie output flow tbmugh a relief valve.-

MILG7979B

set at the maximum powermff pre9eure, intoa fluid grndunte. The average value of dis-placement per stroke, for 5 succoesive 100-pcrccnt strokee of the unit, shall be not kmthan the mted emplacement of the unit.

4.6.12.2 Mechanical afficicmcu (power off).The brake cylinder ahatl be mounted in a testIlxture with meaae pmvidad for meaeuringthe mechanical force applied to the unit. Theunit shall then be opemted (power off)through at kmat 90 percent of ita availablestroke to produce tbe maximum pewer+ffoutput pressure, and the mechanical forceof the unit required to produce thie prceeumshall be meneured. The ratio of the forcecolcutated to produce the came hydreulicpre9aure in the unit, neglecting packing,mechnntcal friction, end return mecheniamform9, h the force actually re@red, ehalfbe known ae the mechanical etlkiency. Themntmctor shall establiah the acceptable etli-ciency for ench application, and test resultsshall ho inctudad in the data submitted eerequired under 4.4.

EfEcimcy (percent) =

Calculated force (lb) X 100(1)

Acturd force (lb)

4.6.13 Boost rutio. ‘IIre broke cylinder ehallbe mounted in a test Wre with a meanepmvidcd for applying various actuetingforces to the cylinder. An input preseuresource ehall bc cormectcd to the preeeureport, and a auitnble gage shell be connectedto the brake port. Actuating forces fmmr-cm to the force required to produce themaxim~ cower on output preeeure eballbe applied to the unit in 25-percent timementa of the force required to produce themaximum power on output preseure. Ateach actuating force, the output preseuredeveloped AaI1 be recorded, and a curve oftbe actuating force veraoe the output pre9-sure shell be plotted. The ,&t ehall then berepeated with the power ?tf ueing the earruactuating f0rce9 ee with the power on. The

11


I

MIL-C-7979B

boost ratio shall then be calculated from the aPPli~tiOn,and test resultsshallbe in. ●followingequation.Tke contractors~l cfuded in the data submitted as required

establish- the-acceptable boost ratio for each under 4.4.

Output pressure with power on for a given actuat~g formBoost ratio = (2)

Output pressure with power off for a given actuating force

4.6.14 Burst pressure. WMr the brake cyl-inder lying free on a bench, burst test pree-eure shall be applied ae follows:

(a) With the pressure and return Portsplugged, apply a pressure whichis equal to 2.5 times the maximumpower-on output pressure to thebrake port.

(b) WMh the return and brake pokopen, apply 2.5 times the inputpressure at the pressure port.

There shall be no external ldrage or ruptureof pati in the above teats.

4.6.15 Packing and marking. The inepec-tor shall ascertain that the packing andmarking of the brake cylinders conform totbie 8pecitication.

5. PREPAI&TON FOR DELIVERY

5.1 General. The provisions contained ine.ecbion 5 of Specification MIL-H~’775, asapplicable, form a part of this specification.

6. NOTES

6.1 Intended use. The hydraulic ~wer ee-aieted master brake cylinders covered by thiespecification are intended for use in air-craft hydraulic brake systems as covered bySpecifications MIL-H-6440 and MILB-6584and are the mechanisms used to transformthe force applied by the aircraft personnelinto hydraulic pressure.

6.2 Ordering dat+ Procurement dmumenteabould speoify the following:

(a) Title, number, and date of thisI specitlcation.

(b) Selection of applicable levels of

I packaging and packing.—

6.2.1Itisexpectedthatthe contractorpurchase order will epeeify that two powerbrake valves of each size will be requiredas preproduction samples and that these pre-produtilon samples will be subjected to thePreproduction tests to determine compliancewith the requirements of this specification.The invitation for bide and the contractehordd specify the point of inspection forthese tests. \

6.2.2 Storage euroeil-fance. Itemepreservedand packaged in accordancewith levelBrequirementsmust be inspectedtodetermineconditionwhen not need within the timeperiodindicated.Items not used within thetime period specilled must either k prS-eerved or packaged again in accordance withlevel B reqnirementa in this specification or ●with level A requirements if storage beyondan additional year ie anticipated.

NotlcaWhen Governmentdrawings,speclficatlons,or otherdataareusedforany purposeothruthanin c.annectionwith a derlnitelyrelatedGovemmsntprocurementoperation,the UnitedStati Gav’ern-ment thsrebyincursno responsibilitynor any obli.gctionwhatsoever; and the fact that the Govern-ment may have formulated, furnishd, or tn anyWIIY STIPPUedthe mid drawings, specifications, orother data is not to be regnrded by implication orotherwise as in any manner Iicensi”g theholderor any otherpersm or c.arpratio”,or conveyingany rightsor permission to manufacture, use, orsell any patented invmticm that may in cny way herelated thereto.

Custodians:Army-lh”aportation CorpsN.vy-Buream of Aercmant[e.g

—

12

Air Force

Preparing activity:Navy—Bnrerm of Aeronrmtim

-— ___ —

●


. . .

SPECIFICATION ANALYSIS SHEET I “m=hpb,~Ekdget Wm.. No. 119-RoM

,; lm~~lhis cheat it to b; fiyd.. th qrw.el .it er

& J% Lkp.rtnerll of h?en... lb,. .heet IS pro.tde~ ?.r .b-terme. t or . n r cm.. inwl~ed i. the ..= of b .PCC -

!c~ti.an i. procurmmt . pr .cL* for u, Llcatq . . .

,r,,mua -..,.) .$’1., + a, the L c S,.~zptnE mfoma t”.. o. thou s of thl ap. cxftc. ta n which .i 1 maum tb. L ..i F.b e pr~ ct. c.. be pm. red .i h o

?o==..ta .PA tbe re,”r. of ~bt, }’ar= .i~l be .PP,=Ct*tt% F.1$ m,..s m rarer.. ., e, .t.p e ,. corm,, ,n~ ,er,d ,0 p,,p,tt.~ .ct,v,ty (., ,“d&,.1.d . . r..,,,, A.,.a f).

PCC1F1CA11ON

m (Of #.b.i**@v) Clw MD STATE

m’mfn NO.

1“”~’”

DOLLA=U NT

$

&TCRIAL PROCURED UNDER A

❑ OInlcl 00vt*””c*, CON1,AC1 o ,uBcO*lmAcT

. HAS WY P6RT OF THE SPECIFICATION CREATED PROBLLMS OR REWIRED INTERPRETATION IN PRO~RWENT uSE?. . Glvt ● *nAc.l PM wJMOcmlMD -@olma.

0. 9sceMnI. D*lta”l ron Co#nLcrl#o lMC Dcrlclcmclcs.

!9

MbwWIS ON AN7 SPECIFICATION REWIRE Mcs T ctNwmFctl 100 RIGID

IS WE sPEc IF IcA71w RfSTWt CTt VET

o Y,, o l!. Iv .“,s., 1“ W*1 ..,,

RWKS (Attach..y .rti. r.t d.ta. hi. h..y be. .s. in. i.p,.. i.g lhi**Pecifj..#i*C. .If *h~,**,* .ddi -f“ #i...lp.s.. s. .tt. e t. fe,. andpl. c, bath i. e.f....lop.addrta.. d t.pr.portn.g acttvtty)

,,, ED w (P, i.l, d ., t,p, d . . . . and .. 1,.11?)

r... . . . . , ,,6= . . . . .:. . . . . ...”... m.” 4. . . w,.” ,s onsOLETc ●L,,. “0. 1541s. . . . . ...> m.. -,.. .“.-. . . . . . ., ..-. . --------

LJutixss ‘V’o


cylinders; hydraulic brake, master, power assisted

Documents