4- steps in hoist design

8/20/2019 4- Steps in Hoist Design

1/93

1

Steps in Design of a Hoisting System

©Dr. B. C. Paul 1999 major revision 2012

With Credit to Dr. H. Sevim for Oriinal Boo!


2/93

2

Steps in Design of Hoisting

System Determine the "erforman#e re$uirements

% &suall' means "rodu#tion

% #an also involve fiurin a##e"ta(le sto""in

distan#es ) num(er of levels to (e served under

*hat #onditions

Sele#t hoist t'"e to meet #onstraints


3/93

+

Once Upon a Mine

Dar! Bla#! #oal mine *ill "rodu#e + million

tons of #oal from a sinle level. ,he hoistin

distan#e from loadin "o#!et to dum" (in is1000 ft. ,he mine o"erates 2-0 da's "er 'ear

+ "rodu#tion shifts "er da' *ith hours of

o"eration ea#h "rodu#tion shift. ,he "ea! "rodu#tion *ill (e a(out -000 tons "er shift.

,he averae "rodu#tion is /000 tons "er shift.


4/93

/

Your Mission Jim, Should you

decide to accept it Desin a hoistin s'stem for the Dar! Bla#! Coal

ine.

irst Ste" is to esta(lish the "erforman#ere$uirement.

,he fundamental Ca"a#it' $uation is

% 3 4 P 5 ,

% 3 is re$uirement in ,ons Per Hour

% P is Produ#tion "er shift

% , is the averae shift "rodu#tion time


5/93

-

Which Production Numer Do

We Use! 6#tual "rodu#tion is a distri(ution ) not an

averae num(er

7f *e desin on averae then all the num(ers

a(ove the mean *ill o "ast #a"a#it' ) *e8ll

loose our hih values and not meet

"rodu#tion 7f *e desin on a "ea! that is seldom

a#hieved *e8ll "a' (i (u#!s


6/93

Decision "riteria

7f "ea! a""roa#hes 2 times averae ) need to

#onsider #ost of *or! sto""ae vs. ta!e *or!

sto""aes 7f "ea! is some*hat #lose to averae then

desin for the "ea!

7n e:am"le the "ea! is 12-; of the averae<*hi#h is not #onsidered a sinifi#ant

deviation. Desin for the Pea!=


7/93

What if #ife had not een so

$ind! Cal#ulate the #ost of a "rodu#tion sto""ae

% a' (e #ost of lost "rodu#tion

% a' in#lude "enalties on #ontra#ts% a' in#lude idle la(or #ost

Cal#ulate the amorti>ed #ost of the ne:t

in#rement of "rodu#tion #a"a#it' Che#! multi"le "oints and o for minimum

total #ost.


8/93

?

Pic% production capacity 6""l' formula

% 1/ t"h 4 -000 t5shift 5 hours "rod time

Other desin de#isions need to (e made

% 7s this a @eo"e or a Drum HoistA

% One evel so @eo"e *on8t (e too tri#!'


9/93

&nput My Hoist Distance and

Production 'ate (arget

9

' S"readsheet is

O"ti)Hoist.

e:t ets loo! at some fi:ed

C'#le time elements


10/93

)lements

Ho* on *ill it ta!e for the ore "o#!et doors to

o"en and dro" a load into the s!i"A

On#e the S!i" is in "osition ho* lon *ill it ta!eto de"osit the load into the dum" "oint #huteA

% 6(out ? se#onds to load

% 10 se#onds to dum" is reasona(le

% our load and unload times ma' de"end on other

desin elements of the s'stem.

10


11/93

"reep (ime

Hoists and levators slo* to near

sto" as the' line u" *ith a set level

% Pull a*a' fromthe loadin "oint% Or line u" *ith dum" "oint

% Will &suall' ta!e a (it more time to

line u" *ith the unload "oint

% 2 se#onds to "ull a*a' from load and

/ to line u" *ith dum" is reasona(le.

116 fo*l Beast


12/93

No* We Need to Pic% a Pea%

Speed and a 'ate of S%ip +cceleration

12

,he ma:imum s"eed *e lift at is safet' related. or men there are reulations.

or materials there are uidelines Esho*n in "in!F


13/93

"onsiderations

,his is a @eo"e Hoist

% ,he ro"e is just sittin over a fri#tion *heel

% 7f 7 G"eel out and the ro"e starts to sli" 7 have

a major hoistin a##ident

Hih s"eed and hih a##eleration in#rease

"rodu#tion% But the' also #ause a (i in#rease in motor si>e

and ener' (ill.

1+


14/93

&m going to go for modest speed

and particularly modestacceleration

1/


15/93

-eometry "onsiderations

1-

,*o S!i"s S!i" and Counter)*eiht


16/93

Stopping "onsiderations

1

7f m' #ontrols miss

Sto""in the s!i" at

,he dum" "oint I ho*

ar do 7 have for an

meren#' sto" (efore

,he over)*iend turns

7nto a disasterA

Dum"

Chute

oadin #hute

Shaft Bottom


17/93

-etting Our .irst )stimate

1

&sin a ord(er a""ro:imation of the #'#le time the "roram estimates the si>e

Of s!i" that *ill (e needed to a#hieve the "rodu#tion taret usin the distan#e<

S"eed and a##eleration #onditions s"e#ified.

E,his "art of the s"readsheet is inde"endent of *hether the hoist *as a @eo"e or

6 drum hoistF.


18/93

Our Ne/t (as% is to -et Our

)/act "ycle (ime

1?

,he onl' missin

Pie#e of information

Was *hat is the

Cree" s"eed E2 ft5se#

7s reasona(leF.

E7 *ant8s 'ou mone' for m' fa!e

Jlo(al *armin initiativeF


19/93

Ne/t We Must 0alance S%ip Si1e,

Weight, 'ope Diameters andWheel Si1es

19


20/93

.irst We Need to Pic% + S%ip Si1e

20

We have alread' (een iven a first uess s!i" si>e. We tr' a(out that si>e

6nd then #he#! the a#tual hourl' "rodu#tion a#hieva(le in the red (o: E*e

o* have fiured the e:a#t #'#le time tooF.

6s #an (e seen a 1 ton s!i" *ill et me m' 20 tons5hour.


21/93

Ne/t &ll -o for S%ip Weight

21

7n eneral a s!i" heav' enouh to handle the (anin of ore loadin and

&nloadin *ill *eiht a(out -; of the load *eiht.

O"ti)Hoist estimates this for us (ut leaves us a 'ello* (lan! to #hoose theWeiht. 6 hiher *eiht usuall' means *e are just addin *eihts to our

S!i".


22/93

Ne/t We -o .or 'ope Si1ing

22

@eo"e hoists usuall' have multi"le ro"es in even num(ers< 2< /< < and ? (einCommon. Where that 12 #ame from is unsure.

We need to #onsider (oth hoistin ro"es and tail ro"es. Sometimes tail ro"es

6re used and *orn)out hoist ro"es *hi#h #an #ause tail ro"es to (e the same

6s hoist ro"es.


23/93

My .irst -uess is 2 ropes

3(his is a relati4ely modest depth5

2+

,he red (o: estimates that 7 *ill need a 1.0/ in#h ro"e to rea#h needed

Safet' fa#tors for this de"th.


24/93

.rom Here & Need to -o +nd

)nter My 'ope Properties

2/

7 enter m' ro"e si>e< it8s *eiht and it8s strenth. E7 have the advantae of Havin an estimate of *hat si>e ro"e to tr'F.

,he s"readsheet then #om"ares the a#hieved fa#tor of safet' to *hat is re$uired


25/93

Where Do & -et (hese 'ope

Properties

2-

,he s"readsheet has a

Ko"e "ro"erties ta(le

Kiht (elo* for me to

oo! thins u" on.

78m loo!in for 1.0/

lattened strand

7 o for 1.12-

Weiht 2.2? l(s5ft

Strenth -.9 tons


26/93

)nter My 'ope and "hec% My

.actor of Safety

2

6 fa#tor of safet' #learl' meets a .-


27/93

& Wonder &f & "ould -et +*ay

*ith a 6 inch rope

2

eee I one in#h ro"e is a no"e.


28/93

What if & Use High Strength

Steal!

2?

Oh so #lose (ut still no"e to the ro"e


29/93

With Hoist 'ope Selected & can

no* pic% the Wheel for My Hoist .rame

29

7 need a .- ft *heel Esee "i#! re#ommendationF to avoid (endin m' ro"e to

Shar". Eou #an see *h' 7 *anted a smaller ro"e I it *ould have allo*ed me

,o use a smaller lo*er inertia *heelF.


30/93

No* & Need to Deal *ith (ail

'ope Sim"le #ase is to et used ro"e

6lso easiest to have just one tail ro"e so

have less s*inin and tanlin.

um(er of tail ro"es is #ommonl' less than

num(er of hoist ro"es.

+0


31/93

&m going to try straight across

Using my *orn7out hoist ropes for tail ropes8

+1


32/93

No* &ll "hec% "onditions at My

$eope Wheel

+2

,1 is the *eiht of the heav' loaded side. ,2 is the *eiht of the lihter em"t'

Side.

Kemem(er I onl' fri#tion sto"s the ro"e from sli""in. ,he ratio of ,1 to ,2

ust therefor not (e more than 1.-

Of #ourse 1.9- is reater than 1.- so life is su#!in riht no*.


33/93

+nother Parameter is (read

Pressure

++

@eo"e *heels are normall' lined *ith a leather li!e fri#tional material. Sin#e *eDon8t *ant the ro"es to #ut the material to "ie#es *e need to limit the load to

6(out +00 "si or less.

Well at least one thin *or!ed.


34/93

So What Do & Do No*

ither ,1 is to (i or ,2 is too little

7 #ould loo! at ro"e *eiht (ut the ro"e *eiht

shifts (a#! and forth from ,1 to ,2 de"endin on*here *e are

% ,he ,1 and ,2 ratios are "i#!ed (' the s"readsheet to (e

*orst #ase

7 #ould ma!e m' s!i" lihter % But a liht dut' s!i" #ould et (eat to "ie#es

% 6nd a lihter s!i" *ould also redu#e ,2

+/


35/93

&dea

7f m' s!i"s *ere heavier then the s!i"s *ould

a##ount for a hiher "er#entae of the *eiht.

Sin#e s!i"s are the for ,1 and ,2 ma!in it alarer "ro"ortion *ill even the ratio

E7 #ould ma!e a similar arument for "i#!in

heavier ro"es (ut ro"es are e:"ensive and (iro"es for larer hiher inertia *heelsF.

+-


36/93

Putting 9 tons of Dead Weight on

My s%ips made it more e4en

+

Of #ourse 78m still not there 'et.


37/93

O% : +dding 6;8; dead *eight

tons to the s%ip did it


38/93

So What "an & Do With My (read

Pressure 7 #an8t #hane m' ,1 and ,2

But 7 #an s"read the load over a reater area

% ,hat unfortunatel' *ould mean ettin a (ier

@eo"e *heel

+?


39/93

(here : + 6= ft Wheel Spreads

the #oad

+97 !no* I the inertia situation su#!s.


40/93

"ome to (hin% +out &t : (he

.actor of Safety Suc%s (oo

/0

Ho* "rofound I 7 "ut more *eiht on the ro"e *ithout strenthenin the ro"e

6nd 7 et into safet' fa#tor trou(le.

EWhere the

one' JoesF


41/93

(a%e + #ittle Weight Off the S%ip

and Put + #ittle More On the 'ope

/1


42/93

(ime to Pic% Out Our Motor

/2


43/93

/+

#oo%ing at Hoist Duty "ycle

Hoist doesn8t al*a's run at a sinle s"eed

7nitial a##eleration ) time it starts to move )

(ut its (' the loadin "o#!et so *e don8tGfloor it

Cree" 1 ) #arefull' #ree"s "ast the loadin

area to avoid tearin somethin u" ain a##eleration ) after #lear of loadin area

) hit it u" to full s"eed


44/93

//

Hoist Duty "ycle


45/93

/-

Duty "ycle "ontinued

Kun at ull S"eed ) until 'ou et #lose

enouh to the to" that 'ou8d (etter slo* do*n

or 'ouLll "ut the s!i" u" some"la#e interestin ain De#eleration ) slo* do*n to #ree"

s"eed (efore 'ou ta!e out the dum" (in

Cree" 2 ) move slo*l' into dum" "osition inal De#eleration ) sto" to dum"


46/93

/

What Si1e Motor!

Ke$uired horse"o*er for motor varies

reatl' throuh hoistin #'#le

6djustments are made (' #al#ulatin theKoot ean S$uared EKSF Horse"o*er

re$uirements

,his re$uires ta!in horse"o*er duties atmulti"le "oints throuh the hoistin #'#le


47/93

(he Spreadsheet Does Your

"alculations

/

,he otor Si>in is

6 fun#tion of somethin

Called W I *hat is

that.A


48/93

/?

(he Mystery of the ))W (erm

W stands for e$uivalent effe#tive *eiht Hoist #ontains motors< ears< and lare

*heels that #ontri(ute inertia to the s'stem

durin a##eleration Could o throuh lon hand and #al#ulate

inertia of ever'thin Eif 'ou8re sadisti#

enouhF

6lternative is to use manufa#tures ta(les that

redu#e inertia to an e$uivalent load on a ro"e.


49/93

/9

Norderg )>ui4alent )ffecti4e

Weight "hart


50/93

'eading the "hart

-0

We !no* it is

6 @eo"e hoist

So 7 *ill use

,he @eo"e line

7 !no* 7 have

6 10ft *heel

So 7 start at

10 and read u"

,o the @eo"e

ine


51/93

& (hen 'ead O4er to the

)>ui4alent )ffecti4e Weight

-1

78ll (e #onservative

7n m' readin and

Call it +


52/93

)nter the Numer and -et Motor

Si1ing

-2

Of #ourse understandin

What all these HP1< HP6

6nd ,S stuff is *ould

6dd a lot of understandin


53/93

@eo"e Hoist -+

(he Horsepo*er Demand of a

$eope Hoist O4er (ime #oo%s #i%e (his


54/93

-/

Understanding $eope Duty

"ycles3 ) Wh' is there a stead' flat line for Horse"o*er re$uired in a @eo"eHoist Dut' C'#le

6 ) Horse"o*er is an ener' out"ut "er unit time. 7t ta!es ener' tolift the s!i" load u" the shaft as it travels at full stead' s"eed.


55/93

--

$eope Duty "ycles3 ) Wh' is there a slo"ed line leadin u"*ard from *hen the hoist starts

6 ) When the hoist is o"eratin at less than full s"eed the load is

trans"orted a lesser distan#e "er unit time and thus the ener' out"ut "er

unit time is less. ,he line has a linear slo"e (e#ause the a##eleration rate is

a #onstant.


56/93

-

(he $eope Duty "ycle3 ) Wh' is there a "ea! that dro"s shar"l' to the flat line forHorse"o*er to run the @eo"e

6 ) ou must add additional for#e to a##elerate the load. 6t the end

of the a##eleration "eriod the additional for#e is no loner needed.


57/93

-

$eope Duty "ycles3 ) Wh' is there a (i dro" in horse"o*er at the end of the full s"eed runfor the hoist

6 ) When the hoist de#elerates< the momentum of the load "rovides "art of

the ener' to !ee" the load movin u" the shaft.


58/93

-?

$eope "ycles3 ) Wh' does the line slo"e do*n at the end of the Hoist

C'#le

6 ) ,he load is slo*in do*n and a##umulatin less "otential

ener' "er unit of time.


59/93

-9

$eope "ycles3) Wh' the funn' dashed lines that sho* more "o*er

(ein used at the start and less (ein re#overed at the end.

6 ) ri#tional losses


60/93

@eo"e Hoist 0

+pproach to +ttac%ing the 'MS

Horsepo*er 'e>uirements We *ill #al#ulate #om"onents of Horse"o*er

re$uirements% HP

1 *ill (e the horse"o*er to a##elerate the load

% HP+ *ill (e the horse"o*er to move the load at full s"eed u"

the shaft

% HP2 *ill (e the horse"o*er re#overed from momentum *hen

the load is de#elerated

% HP *ill (e the horse"o*er still re$uired to lift the load after

de#eleration starts

% HP/ and HP- *ill #over fri#tional losses


61/93

You "an See (hose Horsepo*ers

"alculated8

1


62/93

@eo"e Hoist 2

Horsepo*er ?6 3.or $eope

Hoists5 HP1 4 ,S M N2 5 E--0 M M ,aF

% Where ,S is the ,otal Sus"ended oad

% N is the Nelo#it'% is the a##eleration of ravit'

% ,a is the a##eleration time to et the hoist to full

s"eed and in#ludes time to a##elerate to #ree" s"eed

Einitial a##eleration t1F and then to a##elerate to fulls"eed Et+F

% ,a 4 t1 t+


63/93

@eo"e Hoist +

(otal Suspended #oad

,S 4 W 2000 M S 2ME2000MSWF Ko"e Weiht E(oth sidesF

% S and SW are the s!i" *eiht and load in tons

% K is the ro"e *eiht% Be#ause of tail ro"e there is a full lenth of ro"e on (oth s!i" sides


64/93

@eo"e Hoist /

Horsepo*er ?@ 7 Po*er to #ift a

#oaded S%ip at .ull Speed HP+ 4 N M 2000 M S 5 --0

% ote that the s!i" *eiht term is missin

% 7 have a s!i" oin do*n to (alan#e a s!i"#omin u"


65/93

@eo"e Hoist -

Horsepo*er ?A 7 Negati4e

Horsepo*er from Momentum During Deceleration HP2 4 ) ,S M N2 5 E--0 M M ,r F

% Where ,r is time durin de#eleration


66/93

@eo"e Hoist

Horsepo*er ?2 7 #osses in -ears

and Dri4es Derived em"iri#all' rather than (' "h'si#s

fundamentals

HP/ 4 0.111 M E2000 M S M N 5 --0F


67/93

@eo"e Hoist

+pproach to 'MS Horsepo*er

"ontinued We *ill add the different fundamental #om"onents

of horse"o*er to et the horse"o*er needs at

various #ardinal "oints durin the lift

We *ill la(el these #ardinal "oints 6 throuh

% :am"le D is the "ea! "o*er re$uired at the heiht of

the a##eleration "hase

We *ill "ut the horse"o*er values at the #ardinal "oints into the KS horse"o*er e$uation and use

that to si>e the motor.

"alculate Horsepo*er at @


68/93

@eo"e Hoist ?

"alculate Horsepo*er at @

"ardinal Points Point 6 ) Pea! of the 6##eleration Phase HP6 4 HP1 HP+ HP/

Point B ) Durin ull S"eed Kun

HPB 4 HP+ HP/

Point C ) 6t 7nitiation of De#eleration

HPC 4 HP2 HP+ HP/


69/93

Yip : (here are the 4alues

9


70/93

@eo"e Hoist 0

One More Monster Po*er Sin%

,hese Bi otors have an 6rmature to Sin!

a Battleshi"= ) ta!es a lot of inertia to s"in

the thin u" or do*n HP- Eto s"in it u"F 4 0.- M HP6 M 1.2 5 ,a

HP9 Eto s"in do*nF 4 )0.- M HP6 M 1.2 5 ,r


71/93

(hose "alculations are Done (oo

1

" ti " di l P i t f


72/93

@eo"e Hoist 2

"orrecting "ardinal Points for

+rmature +cceleration Point D is the revision of 6 "ea! of

a##eleration

HPD 4 HP6 HP-

Point is revision of C initiation of

De#eleration

HP 4 HPC HP9


73/93

+nd the "alculations +re (here

+

'MS )>uations Depend on


74/93

@eo"e Hoist /

'MS )>uations Depend on

Motor (ype or 6C otor

HPrms 4 E HPD2 M ,a HPB2M ,fs HP2M ,r F5

E 0.- M ,a ,sf 0.- M ,r 0.2- M tr F Q0.-

% Where% ,a is a##eleration time

% ,sf is full s"eed time

% ,r is de#eleration time

% tr is the rest time


75/93

-

'MS Horsepo*er for D" Motors

umerator is the same as 6C

Denominator is #haned to

E 0.- M ,a ,sf 0.- M ,r 0.- Mtr F

KS HP DC 4 umerator5

DenominatorQ0.-


76/93

#oo%s #i%e & Need +out 6A==

HP


77/93

(ime to Pic% the Motors

7 need to #hoose the num(er and si>e of motor and the inertia of the rotor


78/93

"onsider Pic%s

?

78d rather o 6C *ith fre$uen#' #ontrol. 78d li!e to do 2 00 h" motors (ut

With a 10 ft diameter @eo"e *heel 78ll still need ear redu#tion so 7 *ould

Onl' et a(out 9/; transmission I ' "i#! a 12-0 t*o "ole 6C


79/93

Plug7&n My Motor Parameters

and -ear 'eduction )fficiency

9

O! I ,hat seems to *or!

Eote that there are limits to ho* mu#h 'ou #an turn do*n the s"eed of 6 motor *ith varia(le fre$uen#' drivesF


80/93

Our #ast (as% is to Si1e the 0ra%e

?0


81/93

We Want (*o (hings .rom Our

0ra%e Hold the ma:imum "ossi(le u(alan#ed load

*ith a 1.- fa#tor of safet'

7f a full s"eed load "asses the ore dum"s"eed it must "erform an emeren#' sto"

(efore the s!i" #rashes into the to" of the

headframe.

?1


82/93

?2

Ne/t Step is to Design the

0ra%ing System Durin Clut#hin O"erations the Bra!e must hold the

load so it doesnLt o to the shaft (ottom

Desin "ra#ti#e is to rate the (ra!e and #lut#h to hold

the ma:imum load "lus -0;

BK 4 CK 4 ED52F M E 2000MS 2000MSW H M Wr M

nF M E1.-F R&nits are ft)l(s

% D is drum or *heel diameter

% BK and CK are Bra!e and Clut#h Katins in ftMl(s tor$ue

% ote this is the load on one side of a drum hoist if the other is

#lut#hed


83/93

(he Spreadsheet 'uns the

"alculation

?+

7 need to set m' (ra!e ratin to at least this si>e.


84/93

& .ill &n the Numers

?/

Bra!e ratin #omes from the re#ommendation

ass of the rotor #ame from the motor s"e#ifi#ation list

,he ear ratio and s"eed *ere *or!ed to et a *or!a(leKatio and a motor s"eed that *as *ithin the turn)do*n

imit for the motor.


85/93

?-

+nother .actor is 0ra%e

Performance During an )mergency Stop Desin is done on *orst #ase s#enario

% ma:imum un(alan#ed load travelin at full s"eed

% dis#overed *ith a minimum toleran#e distan#e

(efore 'ou ride into the head frame or #rash into the

(ottom

ust either desin for a toleran#e distan#e 'our (ra!e #an sto" in or si>e u" the (ra!e for the

toleran#e 'ou have.

D i " t


86/93

?

Design "oncept

6ssume the Bra!e must fiht aainst thema:imum un(alan#ed load

% Su(tra#t un(alan#ed load from (ra!e #a"a#it'

% ,his leaves the net for#e availa(le for the emeren#'

sto"

&se e*tons Se#ond a*

% @no* the net for#e availa(le

% @no* total mass in motion% Solve for the de#eleration rate

Cal#ulate the time and distan#e to sto"


87/93

?

.ormula

oo! at a:imum differential load

% W 4 E,1 ) ,2F M 2000

% ,1 4 a: load 4 S SW EH M Wr M n52000F% ,2 4 in Balan#in oad 4 SW


88/93

(he Spreadsheet +pplies the

.ormula to -et the DifferentialWeight8

??


89/93

?9

(he Mass that must e Stopped

,o use e*tonLs a* to et or#e Ke$uirements

the load must (e in mass% eans *e must use slus ) some ho* a s'stem made (' @ins usin slus

sounds *ron

4 E W M K 2 WK 2m M JK 2F 5 K 2 ,1 M2000

,2 M 2000 Q 5 +2.2% Where K is the Drum or Wheel Kadius D52

% WK 2m is the inertia of the motor rotor in ft 2

% JK is the ear ratio of the motor to the drive

% ote that the K 2 terms are needed to #onvert rotatin inertia to e$uivalent

mass

Sol4ing for the Deceleration 'ate


90/93

90

Sol4ing for the Deceleration 'ate DK 4 E B ) W F 5

% DK 4 De#eleration Kate

% 4 ass to (e sto""ed

% W 4 et un(alan#ed load E,1 ) ,2F M 2000

% B 4 Bra!e Katin in l(s linear for#e

% Jet B 4 BK 5 K I BK is the Bra!e Katin in tMl(s

6""l'in the De#eleration Kate% ,ime to Sto" 4 , 4 N 5 DK

% Bra!in Distan#e 4 S 4 EN52F M ,

Che#! Bra!in Distan#e 6ainst 6vaila(le or ma!e

sure 'ou have the distan#e


91/93

@eo"e Hoist 91

(he -ear 'atio Prolem

JK 4 N 5 ND

% N is r"m of motor at rated travel s"eed

% ND is r"m of Drum ND 4 N 5 E"i M D F R remem(er 7 need r"m


92/93

Sol4ing for the Mass to e

Stopped

@eo"e Hoist 92


93/93

"hec% Out Our Stopping

Distance

u" I We 6""ear to Be O@

4- steps in hoist design

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