Hydraulic-Arm-Project (1).docx

7/18/2019 Hydraulic-Arm-Project (1).docx

http://slidepdf.com/reader/full/hydraulic-arm-project-1docx 1/31



Contents Page No.

1) Materials used for Hydraulic Arm 62) Introduction to Fluid Power 7

a) Hydraulics 8i) Use of Hydraulics ii) Forces in !i"uid

#) Pneumatics 8$) %ransmission of forces t&rou'& li"uids 11() Pascals !aw 12*) Multi+lication of Forces 1*6) Hydraulic Fluid 17

a) Pro+erties 17#) %y+es of Hydraulic ,uid 22

7) Hydraulic Cylinder 2$a) -+eration 2$#) Parts of cylinder 2(

c) .in'le actin' /s0 ou#le Actin' 2*8) Fluid !ines and Fittin's 26a) .ections of +i+es and tu#in' 27#) .iin' of +i+e and tu#in' 27c) Material of +i+e 28

) 3ri++ers 214) Conclusion $211) 5eference $2

HYDRAULIC ARM



Materials used for Hydraulic ArmInnovation components allow for greater alternative an innovative esigns. !"e# are

not re$%ire& '%t are s%ggeste to 'ring more engineering an innovation to t"e

activit#. (nl# a few innovation components are %s%all# neee to create alternative

esigns& so #o%r s%ppl# of innovation components can 'e %se for man# "#ra%lic

arms an ot"er activities. Here are t"e components t"at are %se in t"is pro)ect*

o H#ra%lic c#liners +,#ringe wit" clips an mo%nts-o H#ra%lic Lines +in#l !%'ing-o Perpenic%lar wooen 'loc/s an Dowelso C"ip 'oaro ,crewso 01 s$%are n%tso 01 was"erso Connector stripso 3alvanise colo%re wireo R%''er 'ano An#t"ing else t"ings li/e t"e rec#cling 'in& woo& metal& plastic& 'ro/en to#s&

etc.

HYDRAULIC ARM Page 4

Fi'ure 101 etailed dia'ram of Hydraulic Arm



I%5-UC%I- %- F!UI P-55l%i power is a term w"ic" was create to incl%e t"e generation& control& an

application of smoot"& e6ective power of p%mpe or compresse 7%is +eit"er

li$%is or gases- w"en t"is power is %se to provie force an motion tomec"anisms. !"is force an motion ma#'e in t"e form of p%s"ing& p%lling& rotating&

reg%lating& or riving. 5l%i power incl%es "#ra%lics& w"ic" involves li$%is& an

pne%matics& w"ic" involves gases. Li$%is an gases are similar in man# respects.

!"e i6erences are pointe o%t in t"e appropriate areas of t"is man%al. !"is

man%al presents man# of t"e f%namental concepts in t"e 8els of "#ra%lics

an pne%matics. It is intene as a 'asic reference for all personnel of t"e

Nav# w"ose %ties an responsi'ilities re$%ire t"em to "ave a /nowlege of

t"e f%namentals of 7%i power.

Conse$%entl#& emp"asis is place primaril# on t"e t"eor# of operation of t#pical 7%i

power s#stems an components t"at "ave applications in naval e$%ipment. Man#

applications of 7%i power are presente in t"is man%al to ill%strate t"e f%nctions an

operation of i6erent s#stems an components. However& t"ese are onl#

representative of t"e man# applications of 7%i power in naval e$%ipment. Inivi%al

training man%als for eac" rate provie information concerning t"e application of

7%i power to speci8c e$%ipment for w"ic" t"e rating is responsi'le.

ADVANTAGES OF FLUID POWER

!"e e9tensive %se of "#ra%lics an pne%matics to transmit power is %e to t"e

fact t"at properl# constr%cte 7%i power s#stems possess a n%m'er of

favo%ra'le c"aracteristics. !"e# eliminate t"e nee for complicate s#stems of

gears& cams& an levers. Motion can 'e trans:mitte wit"o%t t"e slac/ in"erent

in t"e %se of soli mac"ine parts. !"e 7%is %se are not s%')ect to 'rea/age

as are mec"anical parts& an t"e mec"anisms are not s%')ecte to great wear. !"e

i6erent parts of a 7%i power s#stem can 'e convenientl# locate at wiel#

separate points& since t"e forces generate are rapil# transmitte over

consiera'le istances wit" small loss. !"ese forces can 'e conve#e %p an own

or aro%n corners wit" small loss in e;cienc# an wit"o%t complicate mec"anisms.

er# large forces can 'e controlle '# m%c" smaller ones an can 'e

transmitte t"ro%g" comparativel# small lines an ori8ces. If t"e s#stem is well

aapte to t"e wor/ it is re$%ire to perform& an if it is not mis%se& it can

provie smoot"& 7e9i'le& %niform action wit"o%t vi'ration& an is %na6ecte '#

variation of loa. In case of an overloa& an a%tomatic release of press%re can

'e g%arantee& so t"at t"e s#stem is protecte against 'rea/own or strain. 5l%i

power s#stems can provie wiel# varia'le motions in 'ot" rotar# an straig"t:line

trans:mission of power. !"e nee for control '# "an can 'e minimi<e. In

aition& 7%i power s#stems are economical to operate. !"e $%estion ma# ariseas to w"# "#ra%lics is %se in some applications an pne%matics in ot"ers. Man#

HYDRAULIC ARM Page =



5l%iPower

3as

Pne%matics

Li$%i

H#ra%lics

factors are consiere '# t"e %ser an>or t"e man%fact%rer w"en etermining

w"ic" t#pe of s#stem to %se in a speci8c application. !"ere are no "ar an

fast r%les to follow? "owever& past e9perience "as provie some so%n ieas

t"at are %s%all# consiere w"en s%c" ecisions are mae. If t"e application

re$%ires spee& a mei%m amo%nt of press%re& an onl# fairl# acc%rate control& a

pne%matic s#stem ma# 'e %se. If t"e application re$%ires onl# a mei%m.

H95AU!IC. !"e wor hydraulics is 'ase on t"e 3ree/ wor for water& an originall# covere

t"e st%# of t"e p"#sical 'e"avio%r of water at rest an in motion. Use "as

'roaene its meaning to incl%e t"e 'e"avio%r of all li$%is& alt"o%g" it is

primaril# concerne wit" t"e motion of li$%is. H#ra%lics incl%es t"e manner

in w"ic" li$%is act in tan/s an pipes& eals wit" t"eir properties& an

e9plores wa#s to ta/e avantage of t"ese properties.

PUMA%IC. !"e wor pneumaics is a erivative of t"e 3ree/ wor pneumaic! w"ic"

means air& win& or 'reat". It can 'e e8ne as t"at 'ranc" of engineering

science t"at pertains to gaseo%s press%re an 7ow. As %se in t"is man%al&

pne%matics is t"e portion of 7%i power in w"ic" compresse air& or ot"er gas& is %se

to transmit an control power to act%ating mec"anisms. !"is c"apter isc%sses

t"e origin of pne%matics. It isc%sses t"e c"aracteristics of gases an compares

t"em wit" t"ose of li$%is. It also e9plains factors w"ic" a6ect t"e properties of gases& ienti8es an e9plains t"e gas laws& an ienti8es gases

commonl# %se in pne%matics an t"eir press%re ranges. It also isc%sses "a<ars

of pne%matic gases& met"os of controlling contamination& an safet# preca%tions

associate wit" compresse gases

Use "# $ydraulics

!"e "#ra%lic press& invente '# @nglis" man o"n Bra"ma"& was one of t"e

8rst wor/:a'le pieces of mac"iner# evelope t"at %se "#ra%lics in its

operation. It consiste of a pl%nger p%mp pipe to a large c#liner an a ram.

HYDRAULIC ARM Page



!"is press fo%n wie %se in @nglan 'eca%se it provie a more e6ective an

economical means of appl#ing large forces in in%strial %ses. !oa#& "#ra%lic

power is %se to operate man# i6erent tools an mec"anisms. In a garage& a

mec"anic raises t"e en of an a%to:mo'ile wit" a "#ra%lic )ac/. Dentists an

'ar'ers %se "#ra%lic power& t"ro%g" a few stro/es of a control lever& to lift an

position t"eir c"airs to a convenient wor/ing "eig"t. H#ra%lic oorstops /eep

"eav# oors from slamming. H#ra%lic 'ra/es "ave 'een stanar e$%ipment

on a%to:mo'iles since t"e 14s. Most a%tomo'iles are e$%ippe wit" a%tomatic

transmissions t"at are "#ra%licall# operate. Power steering is anot"er application

of "#ra%lic power. Constr%ction wor/ers epen %pon "#ra%lic power for t"e

operation of vario%s components of t"eir e$%ipment. 5or e9ample& t"e 'lae of

a '%llo<er is normall# operate '# "#ra%lic power. D%ring t"e perio preceing

Eorl Ear II &t"e Nav# 'egan to appl# "#ra%lics to naval mec"anisms

e9tensivel#. ,ince t"en& naval applications "ave increase to t"e point w"ere

man# ingenio%s "#ra%lic evices are %se in t"e sol%tion of pro'lems of g%nner#&

aerona%tics& an navigation. A'oar s"ip& "#ra%lic power is %se to operate s%c"

e$%ipment as anc"or winlasses& cranes& steering gear& remote control evices& anpower rives for elevating an training g%ns an roc/et la%nc"ers. @levators on

aircraft carriers %se "#ra%lic power to transfer aircraft from t"e "angar ec/ to

t"e 7ig"t ec/ an vice versa. H#ra%lics an pne%matics +c"apter 11- are

com'ine for some applications. !"is com'ination is referre to as hydr"

pneumaics% An e9ample of t"is com'ination is t"e lift %se in garages an

service stations. Air press%re is applie to t"e s%rface of "#ra%lic 7%i in a

reservoir. !"e air press%re forces t"e "#ra%lic 7%i to raise t"e lift.

FOR&ES IN LI'UIDS

!"e st%# of li$%is is ivie into two main parts* li$%is at rest +"#rostatics- an

li$%is in motion +"#ra%lics-.!"e e6ects of li$%is at rest can often 'e

e9presse '# simple form%las. !"e e6ects of li$%is in motion are more

i;c%lt to e9press %e to frictional an ot"er factors w"ose actions cannot

'e e9presse '# simple mat"ematics. Li$%is "ave a e8nite vol%me '%t ta/e

t"e s"ape of t"eir containing vessel. !"ere are two aitional c"aracteristics

we m%st e9plore prior to proceeing. Li$%is are almost incompressi'le.

5or e9ample& if a press%re of 1 po%ns per s$%are inc" +psi- is applie to a

given vol%me of water t"at is at atmosp"eric press%re& t"e vol%me will ecrease '# onl# .4 percent. It wo%l ta/e a force of appro9imatel# 42 tons to re%ce

its vol%me '# 1 percent? "owever& w"en t"is force is remove& t"e water

immeiatel# ret%rns to its original vol%me. (t"er li$%is 'e"ave in a'o%t t"e same

manner as water. Anot"er c"aracteristic of a li$%i is t"e tenenc# to /eep its

free s%rface level. If t"e s%rface is not level& li$%is will 7ow in t"e

irection w"ic" will ten to ma(e t"e s%rface level.

LI'UIDS AT REST

HYDRAULIC ARM Page F



In st%#ing 7%is at rest& we are concerne wit" t"e transmission of force an

t"e factors w"ic" a6ect t"e forces in li$%is. Aitionall#& press%re in an on

li$%is an factors a6ecting press%re are of great importance.

PRESSURE AND FOR&E

!"e terms #"rce an pressure are %se e9tensivel# in t"e st%# of 7%i

power. It is essential t"at we isting%is" 'etween t"e terms. 5orce means a total p%s" or p%ll. It is t"e p%s" or p%ll e9erte against t"e total area

of a partic%lar s%rface an is e9presse in po%ns or grams. Press%re means t"e

amo%nt of p%s" or p%ll +force- applie to eac" %nit area of t"e s%rface an is

e9presse in po%ns per s$%are inc" +l'>in2- or grams per s$%are centimetre

+gm>cm2-. Press%re ma#'e e9erte in one irection& in several irections& or in

all irections.

Comp%ting 5orce& Press%re& an Area*:

A form%la is %se in comp%ting force& press%re& an area in 7%i power s#stems. In t"is form%la&

. . . . . . . . . . . . . . . . . . . . . . . . e$%ation +1-

P refers to press%re&

5 inicates force&

an A represents area.

5orce e$%als press%re times area.Press%re e$%als force ivie '# area. B# rearranging t"e form%la t"is statement ma#

'e conense into.

P G F

A

,ince area e$%als force ivie '# press%re& t"e form%la is written

HYDRAULIC ARM Page

5GP

!"is 8g%re ill%strates a memor# evice forrecalling t"e i6erent variations of t"is form%la.

An# letter in t"e triangle ma# 'e e9presse as

t"e pro%ct or $%otient of t"e ot"er two&

epening on its position wit"in t"e triangle.

5or e9ample& to 8n area& consier t"e letter A as

'eing set o6 to itself& followe '# an e$%al sign.

Now loo/ at t"e ot"er two letters. !"e letter 5 is

a'ove t"e letter P? t"erefore&



-%: ,ometimes t"e area ma# not 'e e9presse in s$%are %nits. If t"e s%rface is

rectang%lar& #o% can etermine its area '# m%ltipl#ing its lengt" +sa#& in inc"es- '# its

wit"+also in inc"es-. !"e ma)orit# of areas #o% will consier in t"ese calc%lations are

circ%lar in s"ape. @it"er t"e rai%s or t"e iameter ma# 'e given& '%t #o% m%st /now t"e

rai%s in inc"es to 8n t"e area. !"e rai%s is one:"alf t"e iameter. !o etermine t"e

area& %se t"e form%la for 8ning t"e area of a circle. !"is is written A Gw"ere A is t"e area

A =π r2

& J is 4.1=1F +4.1= or 4 1> for most calc%lations-& an r2 inicates t"e rai%s

s$%are.

%5A.MI..I- -F F-5C. %H5-U3H !I;UI.E"en t"e en of a soli 'ar is str%c/& t"e main force of t"e 'low is carrie straig"t

t"ro%g" t"e 'ar to t"e ot"er en +8g. 2:=& view A-. !"is "appens 'eca%se t"e 'ar

is rigi. !"e irection of t"e 'low almost entirel# etermines t"e irection of

t"e transmitte force.

Fi'ure 2<$0=ects of atmos+&eric +ressure

HYDRAULIC ARM Page K

!"e more rigi t"e 'ar& t"e less

force is lost insie t"e 'ar ortransmitte o%twar at rig"t

angles to t"e irection of t"e

'low. E"en a force is applie to

t"e en of a col%mn of con8ne

li$%i +8g. 2:=& view B-& it is

transmitte straig"t t"ro%g" to

t"e ot"er en an also e$%all#

an %niminis"e in ever#

irection t"ro%g"o%t t"e col%mnforwar& 'ac/war& an siewa#s

so t"at t"e containing vessel is

literall# 8lle wit" press%re. An

e9ample of t"is istri'%tion of

force is ill%strate in 8g%re 2:.

!"e 7at "ose ta/es on a circ%lar

cross section w"en it is 8lle wit"

water %ner press%re. !"e

o%twar p%s" of t"e water is

e$%al in ever# irection.



Fi'ure 2<*0>istri#ution of force

Pascals !aw !"e fo%nation of moern "#ra%lics was esta'lis"e w"en Pascal iscovere t"at

press%re in a 7%i acts e$%all# in all irections. !"is press%re acts at rig"t angles to

t"e containing s%rfaces. If some t#pe of press%re ga%ge& wit" an e9pose

face& is place 'eneat" t"e s%rface of a li$%i +8g. 2:F- at a speci8c ept" an

pointe in i6erent irections& t"e press%re will rea t"e same. !"%s& we can sa# t"at

press%re in a li$%i is inepenent of irection. Press%re %e to t"e weig"t of a

li$%i& at an# level& epens on t"e ept" of t"e 7%i from t"e s%rface. If t"e e9pose

face of t"e press%re ga%ges& 8g%re 2:F& are move closer to t"e s%rface of t"e li$%i&t"e inicate press%re will 'e less. E"en t"e ept" is o%'le& t"e inicate

press%re is o%'le. !"%s t"e press%re in a li$%i is irectl# proportional to t"e

ept". Consier a container wit" vertical sies+8g. 2:- t"at is 1 foot long an 1

foot wie. Let it 'e 8lle wit" water 1 foot eep& proviing 1c%'ic foot of water.

Ee learne earlier in t"is c"apter t"at 1 c%'ic foot of water weig"s

F2.=po%ns. Using t"is information an e$%ation& P G 5>A& we can calc%late t"e

press%re on t"e 'ottom of t"e container.

,ince t"ere are 1== s$%are inc"es in 1 s$%are foot

!"is can 'e state as follows* t"e weig"t of a col%mn of water 1 foot "ig"&

"aving a cross:sectional area of 1 s$%are inc"& is .=44 po%n. If t"e ept" of

HYDRAULIC ARM Page

Fi'ure 2<(0>%ransmission of force: ?A)



t"e col%mn is triple& t"e weig"t of t"e col%mn will 'e 4 9 .=44& or 1.2po%ns&

an t"e press%re at t"e 'ottom will 'e1.2 l'>in2 +psi-& since press%re e$%als

t"e force ivie '# t"e area. !"%s& t"e press%re at an# ept" in a li$%i is

e$%al to t"e weig"t of t"e col%mn of li$%i at t"at ept" ivie '# t"e cross:

sectional area of t"e col%mn at t"at ept". !"e vol%me of a li$%i t"at pro%ces

t"e press%re is referre to as t"e 7%i "ea of t"e li$%i. !"e press%re of a li$%i %e

to its 7%i "ea is also epenent on t"e ensit# of t"e li$%i. If we let A e$%al

an# cross:sectional area of a li$%i col%mn an " e$%al t"e ept" of t"e

col%mn& t"e vol%me 'ecomes A". Using e$%ation2:=& D G E>& t"e weig"t of t"e li$%i

a'ove area A is e$%al to A"D.

Fi'ure 2<60>Pressure of a li"uid isinde+endent of direction0

,ince press%re is e$%al to t"e force per %nit area& set A e$%al to 1. !"en t"e form%la press%re 'ecomes

P G " D . . . . . . . . . . @$%ation +2-.

It is essential t"at " an D 'e e9presse in similar %nits. !"at is& if D is e9presse in po%ns per c%'ic foot& t"e val%e of " m%st 'e e9presse in feet. If t"eesire press%re is to 'e e9presse in po%ns per s$%are inc"& t"e press%re

form%la& e$%ation 2:& 'ecomes

. . . . . . . . . . . @$%ation +4-.

Pascal was also t"e 8rst to prove '# e9periment t"at t"e s"ape an vol%me of a container in no wa# alters press%re. !"%s in 8g%re2:K& if t"e press%re %e to t"eweig"t of t"e li$%i at a point on "ori<ontal line H is K psi& t"e press%re is K psi ever#w"ere at level H in t"e s#stem. @$%ation 2: also s"ows t"at t"e press%re isinepenent of t"e s"ape an vol%me of a container.


Fi'ure 2<70>ater +ressure in a 1<cu#ic<



Pressure and F"rce in Fluid P")er Sysems

Recall t"at& accoring to Pascals law& an# force applie to a con8ne 7%i is

transmitte in all irections t"ro%g"o%t t"e 7%i regarless of t"e s"ape of t"econtainer. Consier t"e e6ect of t"is in t"e s#stem s"own in 8g%re 2:. If t"ere is a

resistance on t"e o%tp%t piston an t"e inp%t piston is p%s"e ownwar& a press%re

is create t"ro%g" t"e 7%i& w"ic" acts e$%all# at rig"t angles to s%rfaces in all

parts of t"e container. If force 1 is 1 po%ns an t"e area of t"e inp%t piston is 1

s$%are inc"es& t"en t"e press%re in t"e 7%i is 1 psi

Fi'ure 2<0>Force transmitted t&rou'& ,uid

-%: 5l%i press%re cannot 'e create wit"o%t resistance to 7ow. In t"is

case& resistance is provie '# t"e e$%ipment to w"ic" t"e o%tp%t piston is

attac"e. !"e force of resistance acts against t"e top of t"e o%tp%t piston.

!"e press%re create in t"e s#stem '# t"e inp%t piston p%s"es on t"e

%nersie of t"e o%tp%t piston wit" a force of 1 po%ns on eac" s$%are inc".

In t"is case& t"e 7%i col%mn "as a %niform cross section& so t"e area of t"e

o%tp%t piston is t"e same as t"e area of t"e inp%t piston& or 1 s$%are inc"es. !"erefore& t"e %pwar force on t"e o%tp%t piston is 1 po%ns+1

HYDRAULIC ARM



psi 9 1 s$. in.-& t"e same as t"e force applie to t"e inp%t piston. All t"at was

accomplis"e in t"is s#stem was to transmit t"e 1:po%n force aro%n t"e 'en.

However& t"is principle %ner:lies practicall# all mec"anical applications of 7%i

power. At t"is point #o% s"o%l note t"at since Pascals law is inepenent of

t"e s"ape of t"e container& it is not necessar# t"at t"e t%'e connecting

t"e two pistons "ave t"e same cross:sectional area of t"e pistons. A connection of

an# si<e& s"ape& or lengt" will o& as long as an %no'str%cte passage is

provie. !"erefore& t"e s#stem s"own in 8g%re 2:1& wit" a relativel# small& 'ent

pipe connecting two c#liners& will act e9actl# t"e same as t"e s#stem s"own in

5ig%re 2:.

MU!%IP!ICA%I- -F F-5C.0 Consier t"e sit%ation in 8g%re 2:11& w"ere t"e inp%t piston is m%c"

smaller t"an t"e o%tp%t piston. Ass%me t"at t"e area of t"e inp%t piston is

2s$%are inc"es. Eit" a resistant force on t"e o%tp%t piston a ownwar force of 2

po%ns acting on t"e inp%t piston creates a press%re of20

2 or 1 psi in t"e 7%i.

Alt"o%g" t"is force is m%c" smaller t"an t"e force applie in 8g%res 2: an 2:1& t"e

press%re is t"e same. !"is is 'eca%se t"e force is applie to a smaller area.

Fi'ure 2<140>%ransmittin' force t&rou'& a small +i+e

!"is press%re of 1 psi acts on all parts of t"e 7%i container& incl%ing t"e 'ottom

of t"e o%tp%t piston. !"e %pwar force on t"e o%tp%t piston is 2 po%ns +1

po%ns of press%re on eac" s$%are inc"-. In t"is case& t"e original force "as 'een

m%ltiplie tenfol w"ile %sing t"e same press%re in t"e 7%i as 'efore. In an# s#stem

wit" t"ese imensions& t"e ratio of o%tp%t force to inp%t force is alwa#s ten to

one& regarless of t"e applie force. 5or e9ample& if t"e applie force of t"e inp%t

piston is po%ns& t"e press%re in t"e s#stem will 'e 2 psi. !"is will s%pport a

resistant force of po%ns on t"e o%tp%t piston.

HYDRAULIC ARM



Fi'ure 2<110>Multi+lication of forces

!"e s#stem wor/s t"e same in reverse. If we c"ange t"e applie force an place a

2:po%n force on t"e o%tp%t piston +8g. 2:11-& ma/ing it t"e inp%t piston& t"e

o%tp%t force on t"e inp%t piston will 'e one:tent" t"e inp%t force& or 2po%ns. +,ometimes s%c" res%lts are esire.-!"erefore& if two pistons are

%se in a 7%i power s#stem& t"e force acting on eac" piston is irectl#

proportional to its area& an t"e magnit%e of eac" force is t"e pro%ct of t"e

press%re an t"e area of eac" piston.




H95AU!IC F!UI.D%ring t"e esign of e$%ipment t"at re$%ires 7%i power& man# factors are

consiere in selecting t"e t#pe of s#stem to 'e %se"#ra%lic& pne%matic& or a

com'ination of t"e two. ,ome of t"e factors are re$%ire spee an acc%rac# of

operation& s%rro%ning atmosp"eric conitions& economic conitions& availa'ilit#

of replacement 7%i& re$%ire press%re level& operating temperat%re range& contamination possi'ilities& cost of transmission lines& limitations of t"e e$%ipment&

l%'ricit#& safet# to t"e operators& an e9pecte service life of t"e e$%ipment.

After t"e t#pe of s#stem "as 'een selecte& man# of t"ese same factors m%st

'e consiere in selecting t"e 7%i for t"e s#stem. !"is c"apter is evote to

"#ra%lic 7%is. Incl%e in it are sections on t"e properties an c"aracteristics

esire of "#ra%lic 7%is? t#pes of "#ra%lic 7%is? "a<ars an safet#

preca%tions for wor/ing wit"& "anling& an isposing of "#ra%lic li$%is?

t#pes an control of contamination? an D%ring t"e esign of e$%ipment t"at

re$%ires 7%i power& man# factors are consiere in selecting t"e t#pe of s#stemto 'e %se"#ra%lic& pne%matic& or a com'ination of t"e two. ,ome of t"e

factors are re$%ire spee an acc%rac# of operation& s%rro%ning atmosp"eric

conitions& economic conitions& availa'ilit# of replacement 7%i& re$%ire press%re

level& operating tempera:t%re range& contamination possi'ilities& cost of

transmission lines& limitations of t"e e$%ipment& l%'ricit#& safet# to t"e operators&

an e9pecte service life of t"e e$%ipment. After t"e t#pe of s#stem "as 'een

selecte& man# of t"ese same factors m%st 'e consiere in selecting t"e 7%i

for t"e s#stem. !"is c"apter is evote to "#ra%lic 7%is. Incl%e in it are sections

on t"e properties an c"aracteristics esire of "#ra%lic 7%is? t#pes of "#ra%lic 7%is? "a<ars an safet# preca%tions for wor/ing wit"& "anling& an

isposing of "#ra%lic li$%is? t#pes an control of contamination? an

sampling.

PROPERTIES

If 7%iit# +t"e p"#sical propert# of a s%'stance t"at ena'les it to 7ow- an

incompressi'ilit# were t"e onl# properties re$%ire& an# li$%i not too t"ic/

mig"t 'e %se in a "#ra%lic s#stem. However& a satisfactor# li$%i for a

partic%lar s#stem m%st possess a n%m'er of ot"er properties. !"e most importantproperties an some c"aracteristics are isc%sse in t"e following paragrap"s.

VIS&OSIT*

iscosit# is one of t"e most important properties of "#ra%lic 7%is. It is a

meas%re of a 7%is resistance to 7ow. A li$%i& s%c" as gasoline& w"ic" 7ows

easil# "as a low viscosit#? an a li$%i& s%c" as tar& w"ic" 7ows slowl# "as a "ig"

viscosit#. !"e viscosit# of a li$%i is a6ecte '# c"anges in temperat%re

an press%re. As t"e temperat%re of a li$%i increases& its viscosit# ecreases.

!"at is& a li$%i 7ows more easil# w"en it is "ot t"an w"en it is col. !"eviscosit# of a li$%i increases as t"e press%re on t"e li$%i increases. A satisfactor#

HYDRAULIC ARM Page 1=



li$%i for a "#ra%lic s#stem m%st 'e t"ic/ eno%g" to give a goo seal at

p%mps& motors& valves& an so on. !"ese components epen on close 8ts for

creating an maintaining press%re. An# internal lea/age t"ro%g" t"ese

clearances res%lts in loss of press%re& instantaneo%s control& an p%mp e;cienc#

.Lea/age losses are greater wit" t"inner li$%is+low viscosit#-. A li$%i t"at is too

t"in will also allow rapi wearing of moving parts& or of parts t"at operate %ner

"eav# loas. (n t"e ot"er "an& if t"e li$%i is too t"ic/ +viscosit# too "ig"-&t"e

internal friction of t"e li$%i will ca%se an increase in t"e li$%is 7ow

resistance t"ro%g" clearances of closel# 8tte parts& lines& an internal passages.

!"is res%lts in press%re rops t"ro%g"o%t t"e s#stem& sl%ggis" operation of t"e

e$%ipment& an an increase in power cons%mption.

+easuremen "# Visc"siy

iscosit# is normall# etermine '# meas%ring t"e time re$%ire for a 89e

vol%me of a 7%i+at a given temperat%re- to 7ow t"ro%g" a cali'rate ori8ce

or capillar# t%'e. !"e instr%ments %se to meas%re t"e viscosit# of a li$%i

are /nown as viscometers or viscosimeters. ,everal t#pes of viscosimeters are in

%se toa#. !"e ,a#'olt viscometer& s"own in 8g%re 4:1&meas%res t"e time

re$%ire& in secons& for Fmilliliters of t"e teste 7%i at 15 to pass

t"ro%g" a stanar ori8ce. !"e time meas%re is %se to e9press t"e 7%is

viscosit#& in ,a#'olt %niversal secons or ,a#'olt f%rol secons. !"e glass

capillar# viscometers& s"own in 8g%re 4:2& are e9amples of t"e secon t#pe

of viscometer %se. !"ese viscometers are %se meas%re /inematic viscosit#.

Li/e t"e ,a#'olt viscometer& t"e glass capillar# meas%res t"e time in secons

re$%ire for t"e teste 7%i to 7ow t"ro%g" t"e capillar#. !"is time is m%ltiplie '#

t"e temperat%re constant of t"e viscometer in %se to provie t"e viscosit#& e9presse in centisto/es. !"e following form%las ma# 'e %se to convert

centisto/es +c,t %nits- to appro9imate ,a#'olt %niversal secons +,U, %nits-.

Fi'ure $<10>.ay#olt /iscometer

Visc"siy Inde,


5or ,U, val%es 'etween

42 an 1

5or ,U, val%es greater

t"an 1*



!"e viscosit# ine9 +.I.- of oil is a n%m'er t"at inicates t"e e6ect of temperat%re

c"anges on t"e viscosit# of t"e oil. A low .I. signi8es relativel# large c"ange

of viscosit# wit" c"anges of temperat%re. In ot"er wors& t"e oil 'ecomes

e9tremel# t"in at "ig" temperat%res an e9tremel# "ic/ at low temperat%res. (n t"e

ot"er "an& a "ig" .I. signi8es relativel# little c"ange in viscosit# over a wie

temperat%re range. Ieal oil for most p%rposes is one t"at maintains a

constant viscosit# t"ro%g" o%t temperat%re c"anges. !"e importance of t"e .I. can

'e s"own easil# '# consiering a%tomotive l%'ricants. An oil "aving a "ig" .I.

resists e9cessive t"ic/ening w"en t"e engine is col an& conse$%entl#& promotes

rapi starting an prompt circ%lation? it resists e9cessive t"inning w"en t"e motor

is "ot an t"%s provies f%ll l%'rication an prevents e9cessive oil cons%mption.

Anot"er e9ample of t"e importance of t"e .I.is t"e nee for a "ig" .I. "#ra%lic oil for

militar# aircraft& since "#ra%lic control s#stems ma# 'e e9pose to

temperat%res ranging from 'elowOF5 at "ig" altit%es to over 15 on

t"e gro%n. 5or t"e proper operation of t"e "#ra%lic control s#stem& t"e "#ra%lic

7%i m%st "ave a s%;cientl# "ig" .I. to perform its f%nctions at t"e e9tremes

of t"e e9pecte temperat%re range. Li$%is wit" a "ig" viscosit# "ave a greaterresistance to "eat t"an low viscosit# li$%is w"ic" "ave 'een erive from t"e

same so%rce. !"e average "#ra%lic li$%i "as a relativel# low viscosit#.

5ort%natel#& t"ere is a wie c"oice of li$%is availa'le for %se in t"e viscosit#

range re$%ire of "#ra%lic li$%is. !"e .I. of an oil ma# 'e etermine if its

viscosit# at an# two temperat%res is /nown. !a'les& 'ase on a large

n%m'er of tests& are iss%e '# t"e American ,ociet# for !esting an Materials

+A,!M-. !"ese ta'les permit calc%lation of t"e .I. from /nown viscosities.

LU-RI&ATING POWER

If motion ta/es place 'etween s%rfaces in contact& friction tens to oppose

t"e motion. E"en press%re forces t"e li$%i of a "#ra%lic s#stem 'etween t"e

s%rfaces of moving parts& t"e li$%i spreas o%t into a t"in 8lm w"ic" ena'les t"e

parts to move more freel#. Di6erent li$%is& incl%ing oils& var# greatl# not onl#

in t"eir l%'ricating a'ilit# '%t also in 8lm strengt". 5ilm strengt" is t"e capa'ilit# of

a li$%i to resist 'eing wipe or s$%ee<e o%t from 'etween t"e s%rfaces w"en sprea

o%t in an e9tremel# t"in la#er. A li$%i will no longer l%'ricate if t"e 8lm 'rea/s

own& since t"e motion of part against part wipes t"e metal clean of li$%i.

L%'ricating power varies wit" temperat%re c"anges? t"erefore& t"e climatic an wor/ing conitions m%st enter into t"e etermination of t"e l%'ricating

$%alities of a li$%i. Unli/e viscosit#& w"ic" is a p"#sical propert#& t"e

l%'ricating power an 8lm strengt" of a li$%i is irectl# relate to its

c"emical nat%re.

&$E+I&AL STA-ILIT*

C"emical sta'ilit# is anot"er propert# w"ic" is e9ceeingl# important in t"e selection of a "#ra%lic li$%i. It is e8ne as t"e li$%is a'ilit# to resist o9iation

HYDRAULIC ARM Page 1F



an eterioration for long perios. All li$%is ten to %nergo %n favo%ra'le

c"anges %ner severe operating conitions. !"is is t"e case& for e9ample& w"en a

s#stem operates for a consiera'le perio of time at "ig" temperat%res.

@9cessive temperat%res& especiall# e9tremel# "ig" temperat%res& "ave a great e6ect

on t"e life of a li$%i. !"e temperat%re of t"e li$%i in t"e reservoir of an operating

"#ra%lic s#stem oes not alwa#s inicate t"e operating conitions

t"ro%g"o%t t"e s#stem. Locali<e "ot spots occ%r on 'earings& gear teet"& or at ot"er

points w"ere t"e li$%i %ner press%re is force t"ro%g" small ori8ces. Contin%o%s

passage of t"e li$%i t"ro%g" t"ese points ma# pro%ce local temperat%res

"ig" eno%g" to car'oni<e t"e li$%i or t%rn it into sl%ge& #et t"e li$%i in t"e

reservoir ma# not inicate an e9cessivel# "ig" temperat%re. Li$%is ma# 'rea/

own if e9pose to air& water& salt& or ot"er imp%rities& especiall# if t"e# are in

constant motion or s%')ecte to "eat. ,ome metals& s%c" as <inc& lea& 'rass& an

copper& "ave %nesira'le c"emical reactions wit" certain li$%is. !"ese

c"emical reactions res%lt in t"e formation of sl%ge& g%ms& car'on& or ot"er

eposits w"ic" clog openings& ca%se valves an pistons to stic/ or lea/& an give poor

l%'rication to moving pars%

FREEDO+ FRO+ A&IDIT*

An ieal "#ra%lic li$%i s"o%l 'e free from acis w"ic" ca%se corrosion of t"e metals

in t"e s#stem. Most li$%is cannot 'e e9pecte to remain completel#

noncorrosive %ner severe operating conitions. !"e egree of aciit# of a li$%i&

w"en new& ma# 'e satisfactor#? '%t after %se& t"e li$%i ma# ten to 'ecome

corrosive as it 'egins to eteriorate.

Certain corrosion an r%st:preventive aitives are ae to "#ra%lic li$%is. ,omeof t"ese aitives are e6ective onl# for a limite perio. !"erefore& t"e 'est proce%re

is to %se t"e li$%i speci8e for t"e s#stem for t"e time speci8e '# t"e s#stem

man%fact%rer an to protect t"e li$%i an t"e s#stem as m%c" as possi'le

from contamination '# foreign matter& from a'normal temperat%res& an from

mis%se.

FLAS$POINT

5las"point is t"e temperat%re at w"ic" a li$%i gives o6 vapo%r in s%;cient

$%antit# to ignite momentaril# or 7as" w"en a 7ame is applie. A "ig" 7as"point isesira'le for "#ra%lic li$%is 'eca%se it provies goo resistance to com'%stion

an a low egree of evaporation at normal temperat%res. Re$%ire 7as"point

minim%ms var# from 45 for t"e lig"test oils to 15 for t"e "eaviest oils.

FIRE POINT




5ire point is t"e temperat%re at w"ic" a s%'stance gives o6 vapo%r in s%;cient

$%antit# to ignite an contin%e to '%rn w"en e9pose to a spar/ or 7ame. Li/e

7as"point& a "ig" 8re point is re$%ire of esira'le "#ra%lic li$%is.

+INI+U+ TO.I&IT*

!o9icit# is e8ne as t"e $%alit#& state& or egree of 'eing to9ic or poisono%s. ,ome

li$%is contain c"emicals t"at are a serio%s to9ic "a<ar. !"ese to9ic or poisono%sc"emicals ma# enter t"e 'o# t"ro%g" in"alation& '# a'sorption t"ro%g" t"e s/in& or

t"ro%g" t"e e#es or t"e mo%t". !"e res%lt is sic/ness an& in some cases& eat".

Man%fact%rers of "#ra%lic li$%is strive to pro%ce s%ita'le li$%is t"at contain

no to9ic c"emicals an& as a res%lt& most "#ra%lic li$%is are free of "armf%l

c"emicals. ,ome 8re:resistant li$%is are to9ic& an s%ita'le protection an care in

"anling m%st 'e provie.

DENSIT* AND &O+PRESSI-ILIT*

A 7%i wit" a speci8c gravit# of less t"an 1.is esire w"en weig"t is critical&alt"o%g" wit" proper s#stem esign& a 7%i wit" a speci8c gravit# greater t"an one

can 'e tolerate. E"ere avoiance of etection '# militar# %nits is esire& a 7%i

w"ic" sin/s rat"er t"an rises to t"e s%rface of t"e water is esira'le. 5l%is "aving a

speci8c gravit# greater t"an 1. are esire& as lea/ing 7%i will sin/& allowing t"e

vessel wit" t"e lea/ to remain %netecte. Recall from c"apter 2 t"at %ner

e9treme press%re a 7%i ma# 'e compresse %p to percent of its original

vol%me. Hig"l# compressi'le 7%is pro%ce sl%ggis" s#stem operation. !"is oes

not present a serio%s pro'lem in small& low:spee operations& '%t it m%st 'e

consiere in t"e operating instr%ctions.

&LEANLINESS

Cleanliness in "#ra%lic s#stems "as receive consiera'le attention recentl#. ,ome

"#ra%lic s#stems& s%c" as aerospace "#ra%lic s#stems& are e9tremel# sensitive

to contamination. 5l%i cleanliness is of primar# importance 'eca%se

contaminants can ca%se component malf%nction& prevent proper valve seating&

ca%se wear in components& an ma# increase t"e response time of servo valves.

5l%i contaminants are isc%sse later. !"e insie of a "#ra%lic s#stem can onl# 'e

/ept as clean as t"e 7%i ae to it. Initial 7%i cleanliness can 'e ac"ieve '#

o'serving stringent cleanliness re$%irements + or '# 8ltering all 7%i ae to

t"e s#stem.

HYDRAULIC ARM Page 1K



H#ra%lic5l%is

Petroli%mBase

,#nt"etic8re

resistant

water'ase 8re:resistant

%9P. -F H95AU!IC F!UI. !"ere "ave 'een man# li$%is teste for %se in "#ra%lic s#stems. C%rrentl#& li$%is

'eing %se incl%e mineral oil& water& p"osp"ate ester& water:'ase et"#lene

gl#col compo%ns& an silicone 7%is. !"e t"ree most common t#pes of

"#ra%lic li$%is are petrole%m:'ase& s#nt"etic 8re:resistant& an water:'ase 8re:

resistant.

PETROLEU+/-ASED FLUIDs

!"e most common "#ra%lic 7%is %se in s"ip'oar s#stems are t"e petrole%m:

'ase oils. !"ese 7%is contain aitives to protect t"e 7%i from o9iation

+antio9iant-& to protect s#stem metals from corrosion +anticorrosion-& to re%ce

tenenc# of t"e 7%i to foam +foam s%ppressant-&an to improve viscosit#.

Petrole%m:'ase 7%is are %se in s%rface s"ips electro "#ra%lic steering an

ec/ mac"iner# s#stems& s%'marines "#ra%lic s#stems& an aircraft

a%tomatic pilots& s"oc/ a'sor'ers& 'ra/es& control mec"anisms& an ot"er

"#ra%lic s#stems %sing seal materials compati'le wit" petrole%m:'ase 7%is.

S*NT$ETI& FIRE/RESISTANT FLUIDS

Petrole%m:'ase oils contain most of t"e esire properties of a "#ra%lic li$%i.

However& t"e# are 7amma'le %ner normal conitions an can 'ecome e9plosive

w"en s%')ecte to "ig" press%res an a so%rce of 7ame or "ig" temperat%res. Non

7amma'le s#nt"etic li$%is "ave 'een evelope for %se in "#ra%lic s#stems w"ere

8re "a<ars e9ist.

WATER/-ASED FIRE/RESISTANTFLUIDS

!"e most wiel# %se water:'ase "#ra%lic 7%is ma# 'e classi8e as water:gl#col

mi9t%res an water:s#nt"etic 'ase mi9t%res. !"e water:gl#col mi9t%re contains

aitives to protect it from o9iation& corrosion& an 'iological growt" an to

en"ance its loa:carr#ing capacit#. !"ere:fore& fre$%ent c"ec/s to maintain t"e

correct ratio of water are important. !"e water:'ase 7%i %se in catap%lt

retracting engines& )et 'last e7ectors& an weapons elevators an "anling

s#stems conforms to MIL:H222.!"e safet# preca%tions o%tline for p"osp"ate

ester 7%i an t"e isposal of p"osp"ate ester 7%i also appl# to water:'ase

7%i conforming to MIL:H:222.


http://www.tpub.com/content/MIL-SPEC/MIL-H/MIL-H-22072C






Hydraulic cylinderA H#ra%lic c#liner +also calle a linear "#ra%lic motor- is a

mec"anical act%ator t"at is %se to give a %niirectional force t"ro%g" a %niirectional

stro/e. It "as man# applications& nota'l# in engineering ve"icles.

Operation

H#ra%lic c#liners get t"eir power from press%ri<e "#ra%lic 7%i& w"ic" ist#picall# oil. !"e "#ra%lic c#liner consists of a c#liner 'arrel& in w"ic"

a piston connecte to a piston ro moves 'ac/ an fort". !"e 'arrel is close on eac"

en '# t"e c#liner 'ottom +also calle t"e cap en- an '# t"e c#liner "ea w"ere

t"e piston ro comes o%t of t"e c#liner. !"e piston "as sliing rings an seals. !"e

piston ivies t"e insie of t"e c#liner in two c"am'ers& t"e 'ottom c"am'er +cap

en- an t"e piston ro sie c"am'er +ro en-. !"e "#ra%lic press%re acts on t"e

piston to o linear wor/ an motion.

5langes& tr%nnions& an>or clevisses are mo%nte to t"e c#liner 'o#. !"e piston ro

also "as mo%nting attac"ments to connect t"e c#liner to t"e o')ect or mac"ine

component t"at it is p%s"ing.

A "#ra%lic c#liner is t"e act%ator or motor sie of t"is s#stem. !"e generator

sie of t"e "#ra%lic s#stem is t"e "#ra%lic p%mp w"ic" 'rings in a 89e or reg%late

7ow of oil to t"e 'ottom sie of t"e "#ra%lic c#liner& to move t"e piston ro

%pwars. !"e piston p%s"es t"e oil in t"e ot"er c"am'er 'ac/ to t"e reservoir. If we

ass%me t"at t"e oil press%re in t"e piston ro c"am'er is appro9imatel# <ero& t"e

force 5 on t"e piston ro e$%als t"e press%re P in t"e c#liner times t"e piston area A*

!"e piston moves instea ownwars if oil is p%mpe into t"e piston ro sie

c"am'er an t"e oil from t"e piston area 7ows 'ac/ to t"e reservoir wit"o%t

press%re. !"e 7%i press%re in t"e piston ro area c"am'er is +P%ll 5orce- > +piston

area : piston ro area-*

w"ere P is t"e 7%i press%re& 5p is t"e p%lling force& Ap is t"e piston face area

an Ar is t"e ro cross:section area.


http://en.wikipedia.org/wiki/Hydraulic_motor

http://en.wikipedia.org/wiki/Actuator

http://en.wikipedia.org/wiki/Force

http://en.wikipedia.org/wiki/Engineering_vehicle


http://en.wikipedia.org/wiki/Hydraulic

http://en.wikipedia.org/wiki/Hydraulic_fluid

http://en.wikipedia.org/wiki/Oil

http://en.wikipedia.org/wiki/Barrel

http://en.wikipedia.org/wiki/Piston

http://en.wikipedia.org/wiki/Piston_rod

http://en.wikipedia.org/wiki/Mechanical_work

http://en.wikipedia.org/wiki/Flange

http://en.wikipedia.org/wiki/Trunnion

http://en.wikipedia.org/wiki/Clevis_fastener

http://en.wikipedia.org/wiki/Hydraulic_pump

http://en.wikipedia.org/wiki/Hydraulic_motor

http://en.wikipedia.org/wiki/Actuator

http://en.wikipedia.org/wiki/Force


http://en.wikipedia.org/wiki/Hydraulic

http://en.wikipedia.org/wiki/Hydraulic_fluid

http://en.wikipedia.org/wiki/Oil

http://en.wikipedia.org/wiki/Barrel

http://en.wikipedia.org/wiki/Piston

http://en.wikipedia.org/wiki/Piston_rod

http://en.wikipedia.org/wiki/Mechanical_work

http://en.wikipedia.org/wiki/Flange

http://en.wikipedia.org/wiki/Trunnion

http://en.wikipedia.org/wiki/Clevis_fastener

http://en.wikipedia.org/wiki/Hydraulic_pump



Parts of a hydraulic cylinder

A "#ra%lic c#liner consists of t"e following parts

&ylinder 0arrel

!"e c#liner 'arrel is mostl# a seamless t"ic/ walle forge pipe t"at m%st 'e

mac"ine internall#. !"e c#liner 'arrel is gro%n an>or "one internall#

&ylinder 0ase "r cap

In most "#ra%lic c#liners& t"e 'arrel an t"e 'ottom portion are wele toget"er. !"is can amage t"e insie of t"e 'arrel if one poorl#. !"erefore& some c#lineresigns "ave a screwe or 7ange connection from t"e c#liner en cap to t"e 'arrel.+,ee !ie ro c#liner& 'elow- In t"is t#pe t"e 'arrel can 'e isassem'le anrepaire.

&ylinder head

!"e c#liner "ea is sometimes connecte to t"e 'arrel wit" a sort of a simple loc/+for simple c#liners-. In general& "owever& t"e connection is screwe or 7ange.5lange connections are t"e 'est& '%t also t"e most e9pensive. A 7ange "as to 'ewele to t"e pipe 'efore mac"ining. !"e avantage is t"at t"e connection is 'oltean alwa#s simple to remove. 5or larger c#liner si<es& t"e isconnection of a screwwit" a iameter of 4 to F mm is a "%ge pro'lem as well as t"e alignment %ringmo%nting.

Pis"n

!"e piston is a s"ort& c#linrical metal component t"at separates t"e two parts of t"ec#liner 'arrel internall#. !"e piston is %s%all# mac"ine wit" grooves to8t elastomeric or metal seals. !"ese seals are often (:rings& U:c%ps or cast iron rings.

!"e# prevent t"e press%ri<e "#ra%lic oil from passing '# t"e piston to t"e c"am'eron t"e opposite sie. !"is i6erence in press%re 'etween t"e two sies of t"e pistonca%ses t"e c#liner to e9ten an retract. Piston seals var# in esign an materialaccoring to t"e press%re an temperat%re re$%irements t"at t"e c#liner will see inservice. 3enerall# spea/ing& elastomeric seals mae from nitrile r%''er or ot"ermaterials are 'est in lower temperat%re environments& w"ile seals mae of iton are

'etter for "ig"er temperat%res. !"e 'est seals for "ig" temperat%re are cast ironpiston rings.

Pis"n r"d

!"e piston ro is t#picall# a "ar c"rome:plate piece of col:rolle steel w"ic"attac"es to t"e piston an e9tens from t"e c#liner t"ro%g" t"e ro:en "ea. Ino%'le ro:en c#liners& t"e act%ator "as a ro e9tening from 'ot" sies of t"episton an o%t 'ot" ens of t"e 'arrel. !"e piston ro connects t"e "#ra%lic act%atorto t"e mac"ine component oing t"e wor/. !"is connection can 'e in t"e form of amac"ine t"rea or a mo%nting attac"ment& s%c" as a ro:clevis or ro:e#e. !"esemo%nting attac"ments can 'e t"reae or wele to t"e piston ro or& in some cases&t"e# are a mac"ine part of t"e ro:en.

HYDRAULIC ARM

http://en.wikipedia.org/wiki/Flanged

http://en.wikipedia.org/wiki/Elastomer

http://en.wikipedia.org/wiki/O-ring

http://en.wikipedia.org/w/index.php?title=U-cup&action=edit&redlink=1

http://en.wikipedia.org/wiki/Cast_iron

http://en.wikipedia.org/wiki/Nitrile_rubber

http://en.wikipedia.org/wiki/Viton

http://en.wikipedia.org/wiki/Flanged

http://en.wikipedia.org/wiki/Elastomer

http://en.wikipedia.org/wiki/O-ring

http://en.wikipedia.org/w/index.php?title=U-cup&action=edit&redlink=1

http://en.wikipedia.org/wiki/Cast_iron

http://en.wikipedia.org/wiki/Nitrile_rubber

http://en.wikipedia.org/wiki/Viton



R"d 1land

!"e c#liner "ea is 8tte wit" seals to prevent t"e press%ri<e oil from lea/ing pastt"e interface 'etween t"e ro an t"e "ea. !"is area is calle t"e ro glan. It often"as anot"er seal calle a ro wiper w"ic" prevents contaminants from entering t"ec#liner w"en t"e e9tene ro retracts 'ac/ into t"e c#liner. !"e ro glan also "asa ro wear ring. !"is wear ring acts as a linear 'earing to s%pport t"e weig"t of t"e

piston ro an g%ies it as it passes 'ac/ an fort" t"ro%g" t"e ro glan. In somecases& especiall# in small "#ra%lic c#liners& t"e ro glan an t"e ro wear ring aremae from a single integral mac"ine part.

Oher pars

C#liner 'ase connection

,eals

C%s"ions

.in'le actin' /s0 dou#le actin'

,ingle acting c#liners are economical an t"e simplest esign. H#ra%lic 7%i

enters t"ro%g" a port at one en of t"e c#liner& w"ic" t"en moves t"e piston toe9ten t"e ro. An e9ternal force ret%rns t"e piston to its normal position anforces t"e "#ra%lic 7%i 'ac/ t"ro%g" t"e s%ppl# t%'ing to t"e 7%i reservoir.

Do%'le acting c#liners "ave a port at eac" en& s%pplie wit" "#ra%lic 7%i for

'ot" t"e retraction an e9tension of t"e piston. !"e# are %se w"ere an e9ternal

force is not availa'le to retract t"e piston or w"ere "ig" force is re$%ire in 'ot"irections of travel.

HYDRAULIC ARM

Fi'ure (01 Hydraulic

http://en.wikipedia.org/wiki/Linear_bearing

http://en.wikipedia.org/wiki/Linear_bearing



An "#ra%lic c#liner s"o%l 'e %se for p%s"ing an p%lling onl#. No 'eningmoments or sie loas s"o%l 'e transmitte to t"e piston ro or t"e c#liner toprevent rapi fail%re of t"e ro seals. 5or t"is reason& t"e ieal connection of an"#ra%lic c#liner is a single clevis wit" a sp"erical 'all 'earing. !"is allows t"e"#ra%lic act%ator to move an allow for an# misalignment 'etween t"e act%ator ant"e loa it is p%s"ing.

In o%r pro)ect we "ave %se ,#ringes wor/ing as "#ra%lic c#liners.

F!UI !I. A FI%%I3. !"e control an application of 7%i power wo%l 'e impossi'le wit"o%t s%ita'le

means of transferring t"e 7%i 'etween t"e reservoir& t"e power so%rce& an t"e

points of application. 5l%i lines are %se to transfer t"e 7%i& an 8ttings are

%se to connect t"e lines to t"e power so%rce an t"e points of application.

TYPES OF LINES

!"ree t#pes of lines is %se in t"is s#stem are pipe +r igi-& t%'ing +semi

rigi- an "ose +7e9i'le-.

!"ere are n%m'er of factors are consiere w"ile selecting t"e line for partic%lar

s#stem. !"ese factors incl%e t"e t#pe of 7%i . re$%ire s#stem press%re an t"e

location of t"e s#stem.

5or e9ample& "eav# pipe mig"t 'e %se for a large stationar# 7%i power s#stem&

'%t comparativel# lig"t weig"t t%'ing m%st 'e %se in aircraft an missiles#stems 'eca%se weig"t an space are critical factors. 5le9i'le "ose is re$%ire in

installations w"ere %nits m%st 'e free to move relative to eac"

PIPES AND TUBIN

!"ere are t"ree important imensions of an# t%'%lar pro%cto%tsie iameter

+(D-& insie iameter +ID-& an wall t"ic/ness. ,i<es of pipe are liste '# t"e

nominal +or appro9imate- ID an t"e wall t"ic/ness. ,i<es of t%'ing are liste

'# t"e act%al (D an t"e wall t"ic/ness.




SELE!TION OF PIPES AND TUBIN

!"e material& ID& an wall t"ic/ness are t"e t"ree primar# consierations in

t"e selection of lines for a partic%lar 7%i power s#stem. !"e ID of a line

is important& since it etermines "ow m%c" 7%i can pass t"ro%g" t"e line in a

given time perio +rate of 7ow-wit"o%t loss of power %e to e9cessive frictionan "eat. !"e velocit# of a given 7ow is less t"ro%g" a large opening t"an

t"ro%g" a small opening. If t"e ID of t"e line is too small for t"e amo%nt of 7ow&

e9cessive t%r'%lence an friction "eat ca%se %nnecessar# power loss an

over"eate 7%i.

Si"in# of Pipes and Tu$in#

Pipes are availa'le in t"ree i6erent weig"ts* stanar +,!D-& or ,c"e%le =?

e9tra strong+Q,-& or ,c"e%le K? an o%'le e9tra strong+QQ,-. !"e sc"e%le

n%m'ers range from 1to 1F an cover 1 istinct sets of wallt"ic/ness. +,ee ta'le :1.- ,c"e%le 1F wall t"ic/ness is slig"tl# t"inner

t"an t"e o%'le e9tra strong. As mentione earlier& t"e si<e of pipes is

etermine '# t"e nominal +appro9imate- ID. 5or e9ample& t"e ID for a 1>=:inc"

,c"e%le = pipe is .4F= inc"& an t"e ID for a 1>2:inc" ,c"e%le= pipe is .F22

inc". It is important to note t"at t"e IDs of all pipes of t"e same nominal si<e are

not e$%al. !"is is 'eca%se t"e (D remains constant an t"e wall t"ic/ness

increases as t"e sc"e%le n%m'er increases. 5or e9ample& a nominal si<e 1:

inc",c"e%le = pipe "as a 1.= ID. !"e same si<e ,c"e%le K pipe "as a . ID&

w"ile ,c"e%le.

%a#le *<10>all %&icBness .c&edule esi'nations for Pi+e

HYDRAULIC ARM Page 2=



1F pipe "as a .K1 ID. In eac" case t"e (D is1.41 +ta'le :1- an t"e

wall t"ic/nesses are0.133(1.315−1.049)

2 &0.179(1.315−9.957)

2 an

0.250(1.315−0.815)2 respectivel#.

%aterials

!"e pipe an t%'ing %se in 7%i power s#stems are commonl# mae from steel&

copper& 'rass& al%mini%m& an stainless steel. @ac" of t"ese metals "as its own

istinct avantages or isavantages in certain applications. ,teel pipe an t%'ing

are relativel# in e9pensive an are %se in man# "#ra%lic an pne%matic s#stems.

,teel is %se 'eca%se of its strengt"& s%ita'ilit# for 'ening an 7anging&

an aapta'ilit# to "ig" press%res an temperat%res .Its c"ief isavantage is its

comparativel# low resistance to corrosion. Copper pipe an t%'ing are sometimes

%se for 7%i power lines. Copper "as "ig" resistance to corrosion an is easil# rawnor 'ent. However &it is %nsatisfactor# for "ig" temperat%res an "as a tenenc#

to "aren an 'rea/ %e to stress an vi'ration. Al%mini%m "as man# of t"e

c"aracteristics an $%alities re$%ire for 7%i power lines. It "as "ig" resistance to

corrosion an is easil# rawn or 'ent. In aition& it "as t"e o%tstaning c"aracteristic

of lig"t weig"t. ,ince weig"t elimination is a vital factor in t"e esign of

aircraft& al%mini%m allo# t%'ing is %se in t"e ma)orit# of aircraft 7%i power

s#stems. ,tainless:steel t%'ing is %se in certain areas of man# aircraft 7%i power

s#stems. As a general r%le& e9pose lines an lines s%')ect to a'rasion or intense "eat

are mae of stainless steel.

!"erefore in maintenance an repair of 7%i power s#stem lines& t"e 'asic esign

re$%irements m%st 'e /ept in min. !wo primar# re$%irements are as follows*

1. !"e lines m%st "ave t"e correct ID to provie t"e re$%ire vol%me an velocit#

of 7ow wit" t"e least amo%nt of t%r'%lence %ring all emans on t"e s#stem.

2. !"e lines m%st 'e mae of t"e proper material an "ave t"e wall t"ic/ness to

provie s%;cient strengt" to 'ot" contain t"e 7%i at t"e re$%ire press%re an

wit"stan t"e s%rges of press%re t"at ma# evelop in t"e s#stem.




3ri++ers3rippers are %se to grasp an "ol o')ects. !"e o')ects are generall# wor/ parts t"at are to

'e move '# t"e "#ra%lic arm. !"ese part "anling applications incl%e mac"ine loaing an

%nloaing& pic/ing parts from a conve#or& an arranging parts into a pallet.

Depening on t"e mec"anism %se for t"e p%rpose of gripping t"e# can 'e classi8e as*

1. Mec"anical 3rippers

2. A"esive 3rippers

4. Hoo/s& ,coops etc

=. ac%%m C%ps

. Magnetic 3rippers

@lectromagnetic grippers are easier to control& '%t re$%ire a so%rce of c power an

an appropriate controller %nit. As wit" an# ot"er ro'otic gripping evice& t"e part m%st

'e release at t"e en of t"e "anling c#cle.

!"is is easier to accomplis" wit" an electromagnet t"an wit" a permanent magnet.E"en t"e part is to 'e release& t"e controller %nit reverses t"e polarit# at a re%ce

HYDRAULIC ARM Page 2F

In o%r pro)ect we "ave %se t"ree

sections of clear 1>K I.D. in#l t%'ing

of i6erent lengt"s.

cm +2.S-

cm+2.S-

11 cm +=4.S-



power leave 'efore switc"ing o6 t"e electromagnet. !"is proce%re acts to cancel t"e

resi%al magnetism in t"e wor/ piece an ens%re a positive release of t"e part.

!"e avantages of magnetic grippers in material "anling applications are*

• Pic/%p times are faster

• ariations in part si<e can 'e tolerate. !"e gripper oes not "ave to 'e esigne for

one partic%lar wor/ part.• !"e# "ave t"e a'ilit# to "anle metal parts wit" "oles +not possi'le wit" vac%%m

grippers.-• !"e# re$%ire onl# one s%rface for gripping.

A isavantage of magnetic grippers is t"e pro'lem of pic/ing %p onl# one s"eet from a stac/.

!"e magnetic attraction tens to penetrate 'e#on t"e top s"eet in t"e stac/ res%lting in t"e

possi'ilit# t"at more t"an a single s"eet will 'e lifte '# t"e magnet. !"is pro'lem can 'e

confronte in several wa#s*

!"e magnetic grippers can 'e esigne to limit t"e e6ective penetration to t"e esire

ept"& w"ic" wo%l correspon to t"e t"ic/ness of t"e top s"eet !"e stac/ing evice %se to "ol t"e s"eets can 'e esigne to separate t"e s"eets for

pic/%p '# t"e ro'ot. (ne s%c" t#pe of stac/ing evice is calle a TfannerS. It ma/es %se

of a magnetic 8el to in%ce a c"arge in t"e ferro%s s"eets in t"e stac/. @ac" s"eet

towars t"e top of t"e stac/ is given a magnetic c"arge& ca%sing t"em to possess t"e

same polarit# an repel eac" ot"er. !"e s"eet at t"e top of t"e stac/ tens to rise

a'ove t"e remainer of t"e stac/& t"%s facilitating pic/%p '# t"e ro'ot gripper.




Fig. 5.1 : Fingers with object-shaped cavity

Fig. 5.2: Fingers with multiple cavities

HYDRAULIC ARM Page 2K

The various types of hand prehension



Fi'0 601 5acB and +inion +arallel aw 'ri++er


Fi' 701 %&e /arious ty+es of &and



C-C!U.I-:(%r esign %ses e9tremel# simple ieas an mec"anisms to ac"ieve a comple9 set of actions an is intene to imitate t"e actions of t"e operators. However& t"ese"#ra%lic arms are e9pensive for small scale in%stries. If t"e ma)or pro'lem of "ig"initial cost is aresse& a ro'otic "#ra%lic arm can 'e intro%ce in an# in%str# to

'ring in a%tomation. !"e mec"anical lin/s an parts t"at "ave 'een fa'ricate aree9tremel# simple. !"at H#ra%lic Arm will:

Reac" t"e greatest istance to eliver a given o')ect. Pic/ %p t"e "eaviest possi'le o')ect. Deliver t"e most o')ects in a given amo%nt of time. 5%nction in an assem'l# line. Have a s#stem to weig" t"e o')ect it pic/s %p. Battle against anot"er arm for an o')ect. Rotate as well as reac" an gra'.

Dig an recover o')ects.

5F5C.:

• "ttp*>>science/it.com>teac"er:gee/:"#ra%lics:pne%matics>c>11>

• "ttp*>>en.wi/ipeia.org>wi/i>H#ra%licc#liner

• "ttp*>>enginemec"anics.tp%'.com>1=1>

• "ttp*>>www."owst%6wor/s.com>transport>engines:e$%ipment>"#ra%lic."tm

• A te9t 'oo/ of 5l%i Mec"anics '# R.V. Bansal


http://sciencekit.com/teacher-geek-hydraulics-pneumatics/c/1091955/

http://en.wikipedia.org/wiki/Hydraulic_cylinder

http://enginemechanics.tpub.com/14105/

http://www.howstuffworks.com/transport/engines-equipment/hydraulic.htm

http://sciencekit.com/teacher-geek-hydraulics-pneumatics/c/1091955/

http://en.wikipedia.org/wiki/Hydraulic_cylinder

http://enginemechanics.tpub.com/14105/

http://www.howstuffworks.com/transport/engines-equipment/hydraulic.htm

Hydraulic-Arm-Project (1).docx

Documents

Transcript of Hydraulic-Arm-Project (1).docx