Crawlers Vs. Truck Cranes

[Rick Rowlands]

What is it about crawler cranes that they don't need outriggers? For example, my K12 crawler has a footprint of 8'6" wide and about 10' long yet it has the same capacity as a K12 truck crane which has outriggers which extend out a good bit farther than 8'6". Does having a lot of weight so close to the ground help stabilize a crawler crane?

Just curious!

 

[Tex3406]

Crawler cranes have rigid frame and steel tracks, forming a solid base. Truck cranes have spring suspension and rubber tyres, and so they need outriggers.

There may be other reasons as well but that is what I think is the case.

 

[Rick Rowlands]

Well I didn't think of that! Thanks

 

[crane operator]

Yeah, they have outriggers because they can't set on suspension. And the width of the outriggers isn't that much more than your crawler version. Typically they made them a single stage extension, and the width was dictated by the width of the truck. Newer boom trucks and some large truck cranes have two stage extensions, just to get more width,(22- 25' wide!) but in that age they made it simple and easy. The engineer's needed outriggers, so they made a single beam and cylinder to stick out. I would guess the truck crane version isn't more than 16-18' wide and it might be less.

 

[td25c]

Your close crane operator.The outriggers on my k-12 Insley truck crane come out about 2 feet,and they are manual pullout riggers.I think the tracked version has more counterwieght so it can have the same capacity on a narrow track frame without the outriggers.Now for another Insley story.The contractor my uncle worked for orderd a new "M model Insley" on tracks in the late 1950's.He had Insley weld on outrigger pockets on the track frame so on some jobs they would install an I-beam in the 4 pockets and crib up under them for more capacity.

 

[Rick Rowlands]

I have thought of adding some additional weight to the tracks to give the crane a bit more stability when making picks off to the side. It certainly wouldn't hurt.

 

[Tommygun]

the lower center of gravity keeps more leverage fighting against the tipping point. everything is alot stiffer with a crawler. i just hate dragging ply wood around to shim up under the tracks on uneven ground on my manitowoc 4000w, but i would take a crawler over a truck crane any day.

 

[Tanstaafl]

Crawler cranes have rigid frame and steel tracks, forming a solid base. Truck cranes have spring suspension and rubber tyres, and so they need outriggers.

There may be other reasons as well but that is what I think is the case.

Sitting on rubber is probably the biggest reason. Lots of give in the tires and suspension so the crane starts to list and get off balance.

Also crawlers weigh quite a bit more than a truck crane does so you can have a smaller footprint and still resist the turning moment of the load.

 

[liebherr1160]

Crawlers well the tracks are the outriggers as everyone Knows..but a truck crane needs the outriggers because you cant truck 18-25 feet what ever down the road ..the suspension ..old rubber block ,leaf spring and so on could easily be chocked...but you will get to wide.
the outriggers serve the purpose of ,getting a wider stance,leveling the crane, most important in that to is that they get the whole carrier of the ground because ..the tire's ,axles ,engine transmission can be deemed counter weight.. ..for max picks on a truck mount i also like a full fuel tank in the carrier....
the biggest reason for getting the carrier clear of the ground when on outrigger's is your axle(s) become the fulcrum point ..instead of the outrigger jack and pad..

try it some time ..you'll feel the and see the difference..

And yes ..the center of gravity off a machine makes a huge difference ..but ..if you weight both machines as they sit ...you'll well find the crawler is a heavier machine than the truck mount ..hence the longer outrigger stance..



Grove made a 22T crawler with a hydraulic boom ...the one i had .,had rubber tracks ..with tracks retracted the machine had no chart ..or hoisting capability... the same crane with the steel track arrangement had a chart for retracted tracks.

that's why you probably have a longer outrigger stance on the K12 truck mount ...huge difference in weight with out the tracks

 

[gr79]

clean military mobile crane

TEREX MAC-50
Seen on display at Selfridge Air Show 2009 (Michigan) :usa
Probably no ho-ho wrappers behind the seats on this one.

 

[gr79]

Posted the 50 because it caught my eye that day that it was folded up, but the outriggers were out, maybe to bulk it up visually for display. Always nice to see equipment.. one tends to get somewhat burned out on aircraft at air shows.

 

[liebherr1160]

Suspension isnt dogged ..

Jacks stroked out ..just as much as the "Mega Trak" ..as Krupp used to call it ...the suspension cylinder's are streched way to far ...

Must have been a sale's man that set it there ..

 

[Lugghead]

.........prolly not the salesman but the oic (officer in charge).......chances are, he read ALL of the manuals though...........the master sergeant that ran it prolly had to hit the latrine during set up.......LOL.......it looks like the a/c unit's in good shape though!!

 

[liebherr1160]

I think thats an oil cooler ...the A/C is in that compartment behind the operators cab ...I believe..

 

[gr79]

no easily vandalized windows!

"Have been fitted with CPKs" :naughty

"The CPK features windows of fully transparent armor, opaque armor siding that has been ATC Aberdeen tested and approved to meet all Operation Iraqi Freedom requirements, a patent-pending combat door lock, tool-less emergency egress windows, fortified door hinges and an integrated crew comfort system". heated seats? hot water maker?

 

[Lugghead]

..........i guess that means that they don't hide the key in the outrigger beam, then........:bouncegri