Human Powered Cranes

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http://www.lowtechmagazine.com/2010/03/history-of-human-powered-cranes.html

The sky is the limit: human powered cranes and lifting devices

From the earliest civilisations right up to the start of the ndustrial !evolution" humans used sheermuscle power" organisation s#ills and ingenious mechanics to lift weights that would $e impossi$le to

handle $y most power cranes in operation today.

The most powerful hand crane in history multiplied the force of its operator 632 times

%he most common tower crane used in construction today has a lifting capacity of some 12 to 20

tonnes. For &uite a few construction pro'ects in ancient history" this type of crane would $e completely

inade&uate.

http://krisdedecker.typepad.com/.a/6a00e0099229e88833017d405b927d970c-pihttp://krisdedecker.typepad.com/.a/6a00e0099229e88833017d405b927d970c-pihttp://krisdedecker.typepad.com/.a/6a00e0099229e8883301b7c815964d970b-pi


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%he ma'ority of stones that ma#e up the almost 1(0 discovered)gyptian pyramids have a weight of *only* 2 to 3 tonnes each" $ut all of these structures +$uilt $etween

2,0 and 100 also hold stone $loc#s weighing 0 tonnes" sometimes more. %he temple of mon-

!a at arna# contains a la$yrinth of 13( columns" standing 23 metres +, feet tall and supporting

cross$eams weighing 0 to ,0 tonnes each. %he 14 capital $loc#s of %ra'an5s column in !ome weighmore than 3 tonnes and they were lifted to a height of 3( metres +111 feet. %he !oman 6upiter temple

in aal$e# contains stone $loc#s weighing over 100 tonnes" raised to a height of 17 metres +2 feet.

%oday" to lift a weight of 0 to 100 tonnes to these heights" you need a crane li#e this.

8ccasionally" our forefathers lifted even heavier stones. %he gravestone of %heoderic the 9reat in!avenna +around 20 is a 2, tonne stone $loc# that was lifted to a height of 10 metres. %he

temple dedicated to ;haraoh hafre in )gypt is made up of monolithic $loc#s weighing up to (2

tonnes. %he largest )gyptian o$elis# weighed more than 00 tons and stands more than 30 metres tall"while the largest o$elis# in the ingdom of


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8nly the most powerful contemporary cranes could

handle stones of this weight +see the picture on the left" specifications here.

!aising construction materials to impressive heights seemed to $e no pro$lem either. %he leor is there a limit

to the height to which this weight can $e lifted. %he only advantage that fossil fuelled powered cranes

have $rought us" is a higher lifting speed . 8f course" this does not mean that one man can lift anythingto any height" or that we can lift anything to any height if we 'ust $ring enough people together. ut"

starting more than "000 years ago" engineers designed a collection of machines that greatly enhanced

the lifting power of an individual or a group of people. ?ifting devices were mainly used for

construction pro'ects" $ut +later also for the loading and unloading of goods" for hoisting sails on ships"and for mining purposes. + picture credit.

The advantage that fossil fuel powered craneshave brought us, is a higher lifting speed

nitially" the lifting speed of lifting machines was e


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re&uired to operate them remained very high. %owards the end of the nineteenth century" however" 'ust

$efore steam power too# over" human powered lifting devices $ecame so ela$orate that one man could

lift a 1 tonne truc# in no time" using only one hand.

Mechanical advantage

ny lifting device has a certain mechanical advantage +=" the factor $y which it multiplies the input

force into an output force. lower input force must always $e applied over a greater distance than thegreater output force travels" and the ratio of the distances is the velocity ratio +@!. n theory" the

mechanical advantage += A the velocity ratio +@!" so that in a machine with a mechanicaladvantage of 2 to 1" the input force is half the output force $ut must $e e


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Bhile the methodsof the )gyptians offered a considera$le mechanical advantage over simply pulling up the load

vertically $y means of a rope" the re&uired man power remained very high: not only to tow or flip over

the stones +it must have ta#en around 0 men to tow a 2. tonne stone $loc#" $ut also to $uild and later remove the enormous earthen ramps.

Cistorians estimate that the wor#force to $uild a pyramid consisted of

20"000 to 0"000 men" sometimes more. Bhile a structure li#e that could $e $uilt today in a few years

time with power cranes and a small wor#force" most pyramids too# decades to complete.

irth of the crane! the pulley

%he first cranes appear in 9reece from a$out the late th or early th century . %he !omans" moreeager to $uild large monuments" adopted the technology and developed it further. %he earliest cranes

consisted of a rope passed over a pulley. efore it found an application in the lifting of o$'ects" the

single pulley was used from the 4th or 7th century onwards for drawing water from wells +the

shaduf . single pulley offers no mechanical advantage in itself" $ut it changes the direction of pull: itis easier to pull down instead of haul up. ;ushing vertically upwards with one hand generates a$out 10

>ewton" while pushing vertically downwards with one hand generates a$out 20 >ewton +source.

http://www.australiancrane.com.au/crane_history1.htmhttp://www.swan.ac.uk/grst/Specific%20subjects/Mechanics/Mechanics.htmhttp://krisdedecker.typepad.com/.a/6a00e0099229e8883301310fcb7118970c-pihttp://krisdedecker.typepad.com/.a/6a00e0099229e888330120a9647114970b-pihttp://krisdedecker.typepad.com/.a/6a00e0099229e8883301310fcb7c82970c-pihttp://www.australiancrane.com.au/crane_history1.htmhttp://www.swan.ac.uk/grst/Specific%20subjects/Mechanics/Mechanics.htm


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9radually" the mechanical advantage of cranes wasincreased with additional technology. ma'or improvement from the (th century and still in use

today" is the compound pulley: a com$ination of single pulleys in a $loc#. %he mechanical advantagee&uals the amount of pulleys used.

crane with a triple pulley +a *%rispastos* has two pulleys attached to the crane and a free pulley

suspended from them. t offers a mechanical advantage of 3 to 1. crane with five pulleys in a similar

arrangement +du$$ed a *;entaspostos* offers a mechanical advantage of to 1.

Dsing a compound pulley a man can lift more than he is otherwise a$le to. f a single man pulling a

rope can e


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mages: 6ohn Epir#o.

n theory" any num$er of pulleys can $e used" $ut $ecause of friction ancient systems were limited to

five pulleys. f more lifting power was needed" rather than increasing the num$er of pulleys within each $loc#" the !omans used two or more 3- or - pulley sets" with different gangs wor#ing each +a

*;olyspastos*. 8f course" every rope could also $e pulled $y several men at once. %he power loss due

to friction for !oman +and medieval cranes is estimated to $e 20 percent at most +source.

$inches and capstans

nother improvement was the introduction of the windlass +or winch and the capstan" which $oth

su$stitute for the pulling of the rope. %hey were invented around the same time as the compound

pulley. %he only difference $etween the winch and the capstan is that the former has a horizontal a


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The treadwheel crane remained in use untilthe end of the %''s

om$ined with the compound pulley" winches orcapstans already offer impressive performance. 8ne man operating a ;entaspostos and e


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Bith a mechanical

advantage of 1( to one" one man in a treadwheel operating a ;entaspastos and e


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)ifting towers

Bhile the lifting capacity of a ancient treadwheel crane is impressive" attentive readers will havenoticed that !oman $uildings contained stone $loc#s that were considera$ly heavier than that. %he

!omans also shipped a few dozens of o$elis#s from )gypt and re-erected them in their cities - theheaviest of these weighing more than 00 tonnes. Cow did they manage this with or 12 ton cranesG

asically" in the same way that we handle very heavy loads" $y com$ining multiple lifting devices.

8ne method was to $uild a gigantic lifting tower powered $y multiple capstans on the ground.

lthough the mechanical advantage of a capstan is considera$ly lower than that of a treadwheel" theycould $e powered $y much more people and so less machines would $e needed. =oreover" they

allowed for the au


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Fontana documented the underta#ing e


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fragment of *%he %ower of a$el* $y ;ieter rueghel the )lder +13.

?uc#ily" a few treadwheel cranes have $een preserved" all of them in the attics of churches andcathedrals. ?arge cranes were an a$solute necessity in the $uilding of the gothic churches in the late

=iddle ges" $uildings that were much higher than even the tallest !oman monuments. Furthermore"

the wor#ing area on these sites was rather limited compared to !oman conditions" and $oth factors led

to a different use of cranes.

.othic churches and cathedrals

=ost pro$a$ly" cranes were installed inside the $uilding" initially on the ground" and moved upwards

+and also sidewards as the construction wor# proceeded" $eing dismantled and reassem$led multipletimes. Bhen the church was finished" some of these cranes were left a$ove the vaulting and $elow theroof where they might come in handy for repairs. +illustration $elow" source.

http://www.lowtechmagazine.com/2008/11/tiles-vaults.htmlhttp://www.amazon.com/gp/product/0953021912?ie=UTF8&tag=lowtemagaz-20&linkCode=as2&camp=1789&creative=9325&creativeASIN=0953021912http://krisdedecker.typepad.com/.a/6a00e0099229e8883301310fc734c3970c-pihttp://www.lowtechmagazine.com/2008/11/tiles-vaults.htmlhttp://www.amazon.com/gp/product/0953021912?ie=UTF8&tag=lowtemagaz-20&linkCode=as2&camp=1789&creative=9325&creativeASIN=0953021912


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8ne of these treadwheel cranes"

in ritain5s anter$ury athedral" was used for a renovation pro'ect in the 17,0s +picture on the right"source. t dates from the late 1th century" could accommodate one to two la$ourers and has a

diameter of (. metres. =edieval illustrators sometimes depicted cranes mounted on the outside of the

walls" $ut this was done pro$a$ly $ecause it made $etter paintings - the walls of gothic churches and

cathedrals were generally too thin to support a heavy crane and its load.

nother well descri$ed medieval lifting device is the large treadwheel slewing

crane that stood on top of the 1, metre high ologne athedral in 9ermany for almost (0 years +onthe right" source. t was erected in 1(00 and dismantled only in 14(2. %he crane housed two

treadwheels" was 1., metres high and had a 1.( metre long 'i$ which could traverse the entirewor#ing area - $asically functioning li#e a modern tower crane.

Harbour cranes

new development in the =iddle ges was the stationary har$our crane" powered $y treadwheels. t

was not used $y the 9ree#s or the !omans" possi$ly $ecause they had a large enough reservoir of slavela$our at their disposal. %he !oman standard shipping container" the amphora" was rather small and

http://www.jstor.org/pss/3106635http://www.amazon.com/gp/product/0953021912?ie=UTF8&tag=lowtemagaz-20&linkCode=as2&camp=1789&creative=9325&creativeASIN=0953021912http://krisdedecker.typepad.com/.a/6a00e0099229e8883301310fcd241f970c-pihttp://krisdedecker.typepad.com/.a/6a00e0099229e8883301310fcd275c970c-pihttp://krisdedecker.typepad.com/.a/6a00e0099229e888330120a9609c73970b-pihttp://www.jstor.org/pss/3106635http://www.amazon.com/gp/product/0953021912?ie=UTF8&tag=lowtemagaz-20&linkCode=as2&camp=1789&creative=9325&creativeASIN=0953021912


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nalogous to post windmills and tower windmills" there were post cranes and

tower cranes: the former were wooden structures which pivoted on a central vertical a


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Elewing $ecame a common feature of construction

cranes in the 100s +illustration on the right" which shortened wor# cycles considera$ly.

%he first crane that allowed a horizontal movement of the load appeared in a 10 $oo# of 9eorgius

gricola" $ut a real-world version was only launched in 1 $y Frenchman laude ;errault. trolleywas moved along the whole length of the 'i$ $y means of a complicated rope system in which two

ropes were wound and unwound via a spindle attached to the trolley. +source.

?et5s not forget that 9ree# and !oman cranes were capa$le of very limited horizontal movement" too"

$y lowering or raising the masts a $it. =oreover" the 9ree#s already designed a #ind of slewing crane"which was a lifting device as descri$ed earlier $ut resting only on one mast" directed and #ept in

$alance $y e


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long as the engine was powerful enough. +source

Bire rope was soon in widespread use" $ut the other two innovations only caught

on slowly. Bood" sometimes com$ined with iron" continued to $e the material of choice for many

cranes well into the twentieth century" especially in regions where tim$er was plentiful. nd whilemore and more steam cranes appeared in the second half of the nineteenth century" hand-powered

cranes #ept $eing sold and used in large amounts. $oo# on crane technology" pu$lished in 170(" still

devoted half of its pages to manually operated cranes. icycle cranes were sold" too +picture on the

right" source.

?ogically" it was also this era that produced the most powerful muscle powered cranes ever designed:those composed of iron structures and gearwor#s" using wire ropes" $ut not yet powered $y steam. 8ne

peculiar eetherlands" used to haul up $oats over land +picture $elow.

http://www.amazon.com/gp/product/0953021912?ie=UTF8&tag=lowtemagaz-20&linkCode=as2&camp=1789&creative=9325&creativeASIN=0953021912http://www.amazon.com/gp/product/0953021912?ie=UTF8&tag=lowtemagaz-20&linkCode=as2&camp=1789&creative=9325&creativeASIN=0953021912http://www.debinnenvaart.nl/binnenvaarttaal/afbeeldingen/landzaken/overhaal.htmlhttp://www.debinnenvaart.nl/binnenvaarttaal/afbeeldingen/landzaken/overhaal.htmlhttp://krisdedecker.typepad.com/.a/6a00e0099229e888330120a966a2a9970b-pihttp://www.amazon.com/gp/product/0953021912?ie=UTF8&tag=lowtemagaz-20&linkCode=as2&camp=1789&creative=9325&creativeASIN=0953021912http://www.amazon.com/gp/product/0953021912?ie=UTF8&tag=lowtemagaz-20&linkCode=as2&camp=1789&creative=9325&creativeASIN=0953021912http://www.debinnenvaart.nl/binnenvaarttaal/afbeeldingen/landzaken/overhaal.htmlhttp://www.debinnenvaart.nl/binnenvaarttaal/afbeeldingen/landzaken/overhaal.html


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=uch less #nown"

however" is that for a short time these powerful cranes were sold as hand powered machines. ecauseFair$airn descri$ed these cranes in detail in the 140 edition of his $oo# *Dseful information for

engineers*" we #now e


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mechanical advantage of 32 to 1 means that each of the four men had to apply a force of only 23.,

#ilograms in order to lift a weight of 0 tonnes - and this while operating a winch instead of a more

efficient treadwheel.

%he most powerful crane in the world today +since Eeptem$er 2007 has a lifting capacity of 20"000tonnes. f it would $e e&uipped with a gear system offering the same mechanical advantage as that of

the a$ove descri$ed Fair$airn crane" a weight of 20"000 tonnes could $e lifted $y 1"2 men each

e


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mechanical advantage of a treadwheel.

• *Dseful information for engineers*" Billiam Fair$airn +140" first edition - all later editions do

not contain the chapter on hand powered cranes. %his $oo# gave proof of the impressive performance of late hand powered cranes.

• *%he construction of cranes and other lifting machinery*" )dward harles !o$ert =ar#s"

+170(. etailed information on late hand powered cranes.•

*uilding %ra'an5s column*" +.pdf" merican 6ournal of rcheology" ?ynne ?ancaster +1777.!oman lifting techni&ues J the use of lifting towers.

• *Ceavy goods handling prior to the nineteenth century*" F.!. For$es %aylor +173. n

overpriced research paper compared to that of ndrea ?. =atthies" $ut it gives some interestingadditional information on har$our cranes. lso names an estimation for the amount of medieval

doc#side cranes in )urope.• *rane*" Bi#ipedia. 9eneral introduction" $ased on two authoritative 9erman $oo#s. Eee also:

list of har$our cranes.

• *laude ;hilip*" illustrations of ancient cranes

• *%heatrum instrumentorum et machinarum*" 6aco$i essoni +142. ncient and medieval crane

types.

• *)ngineering in Cistory +over oo#s on )ngineering *" !ichard Ehelton ir$y +1770. )


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Human Powered Cranes