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Posted (edited)

While the turntable configuration is meant to resemble a thrust roller bearing, the "rollers" have a very limited contact surface resulting in quite high surface loads. Thus, I feel like the LEGO parts that makes up the turntable will wear out quite fast if put under relatively high stress.

I do understand that there are limits to what you can do with LEGO parts though, and I think they have come up with a clever solution here.

Edited by zoo
Posted
52 minutes ago, zoo said:

While the turntable configuration is meant to resemble a thrust roller bearing, the "rollers" have a very limited contact surface resulting in quite high surface loads. Thus, I feel like the LEGO parts that makes up the turntable will wear out quite fast if put under relatively high stress.

I do understand that there are limits to what you can do with LEGO parts though, and I think they have come up with a clever solution here.

It'd be fine if they had like 16 or 24 roller bearings instead of 8.

Posted

I don't think a few kgs if pressure will cause too much damage or wear, not with how slow it will be moving. Obviously more would be better but probably overkill especially considering older turntables have no bearings at all and have a much smaller diameter which increases stress even more.

I wonder if the rollers are mounted to anything to keep them spaced apart.

Posted

I hope there will be a usual turntable piece inside, where "wheel bearings" will be just an extra support.

Posted

Can anyone think of a way that might let multiple functions in the H6 gearbox be run at once? Like another piece that moves the clutches than can also swing on the axle that the selector sits on?

Posted (edited)
1 hour ago, allanp said:

I don't think a few kgs if pressure will cause too much damage or wear, not with how slow it will be moving. Obviously more would be better but probably overkill especially considering older turntables have no bearings at all and have a much smaller diameter which increases stress even more.

It will probably be fine concidering the slow turning speed and typically low loads like you say. However, compared to the large LEGO turntable part this will have a lot less contact surface. Keep in mind that at most half of the "rollers" or discs in this configuration will be carrying all the load unless there are other non visible parts that help carry it, like for example what zux describes above.

It will be very interesting to see the whole configuration once it is revealed. Perhaps there is way more to it than I have seen so far, which there probably are is.

Edited by zoo
Posted (edited)

Maybe the boom can rotate independantly of the superstructure which can also rotate. i.e have a large turntable inside of the cuved gear strips just like the 42055 bucket wheel excavator. Maybe, on the other hand, the superstructure is too cramped for this to be a function.

Edited by SNIPE
Posted (edited)

If you look behind the front bumper you can see the base end of a small linear actuator which I presume is used to work the stabilizers.

Capture.JPG

Edited by tblightning
Posted
16 hours ago, zoo said:

It will probably be fine concidering the slow turning speed and typically low loads like you say. However, compared to the large LEGO turntable part this will have a lot less contact surface. Keep in mind that at most half of the "rollers" or discs in this configuration will be carrying all the load unless there are other non visible parts that help carry it, like for example what zux describes above.

It will be very interesting to see the whole configuration once it is revealed. Perhaps there is way more to it than I have seen so far, which there probably are is.

I don't own any of the train wheels used for the rollers and have just noticed in the picture how thin their edges are. And if there is no "cage" piece that keeps them separated is there a possibility they could all migrate together, so at times their won't be any rollers to support the weight?

Posted
2 minutes ago, allanp said:

I don't own any of the train wheels used for the rollers and have just noticed in the picture how thin their edges are. And if there is no "cage" piece that keeps them separated is there a possibility they could all migrate together, so at times their won't be any rollers to support the weight?

I would bet on a cage structure inside. Why would they use the 2L bar with balljoint otherwise?

Posted

I think a three-stage boom on this crane would have been better. This boom, when lowered in travel position, will be way too long for a rough terrain crane.

Posted
15 hours ago, gvo25 said:

I think a three-stage boom on this crane would have been better. This boom, when lowered in travel position, will be way too long for a rough terrain crane.

Really? What's too long?

craneimg11.png

crane.png

rough terrain is a bit of a misnomer. No crane is made for crazy terrain - that's why they build roads to get them in if required. You need a fundamentally flat(ish) and firm surface to put them on. You can use the crane to modify the surface somewhat by outrigger jacking to level a surface, but you still need to key the mats to the surface, otherwise they or the strut sitting on them will slide down the hill.

 

Rough terrain, in crane terms, really only means a dirt surface, which in turn means nothing more than low pressure tyres. 40/50PSI tyres are the only thing separating a 'rough' terrain crane from a city crane with 120psi road truck tyres. You won't be off-roading any of these things in the sense of a four wheel drivers version of rough terrain - their centre of mass is far to high for reliable safety.

You might find this interesting reading

http://www.cranestodaymagazine.com/features/rubber-matters/

Posted
On 5/20/2018 at 8:02 AM, tblightning said:

If you look behind the front bumper you can see the base end of a small linear actuator which I presume is used to work the stabilizers.

 

It doesn't bother me if the outriggers don't actually lift the crane up. Just as long as the small LAs work to extend the outriggers and place them down reliably then I think that will be a nice function.

Posted
4 hours ago, bonox said:

 

 

rough terrain is a bit of a misnomer. No crane is made for crazy terrain - that's why they build roads to get them in if required. You need a fundamentally flat(ish) and firm surface to put them on. You can use the crane to modify the surface somewhat by outrigger jacking to level a surface, but you still need to key the mats to the surface, otherwise they or the strut sitting on them will slide down the hill.

 

Rough terrain, in crane terms, really only means a dirt surface, which in turn means nothing more than low pressure tyres. 40/50PSI tyres are the only thing separating a 'rough' terrain crane from a city crane with 120psi road truck tyres. You won't be off-roading any of these things in the sense of a four wheel drivers version of rough terrain - their centre of mass is far to high for reliable safety.

You might find this interesting reading

http://www.cranestodaymagazine.com/features/rubber-matters/

Well several years ago, while building a house on a slight hill, in the middle of a plowed corn field, we had a similar crane to set beams. Unfortunately it didn't have enough reach to set a particularly heavy beam at the back of the house, from where the crane was parked on the gravel road driveway. So we had the crane hook up to the beam and with the boom all the way in and lowered the operater drove through the plowed field with the beam to the back of the house and reset the crane in the field on uneven plowed ground and we set the beam no problem. Now granted it was only a slight rise but there is no way another road crane could have navigate that terrain, would have got hung up immediately. Hell my pickup truck couldn't have even drove through that field, wasn't 4x4. Anyway crane had no problem at all, it was pretty cool to watch and I was surprised the operater even agreed to try it, I guess at $150 an hour he figured it was worth it. 

So even if it isn't done often it is doable, no other type of crane could have done that. He was definitely off-road. 

Posted (edited)
1 hour ago, Johnny1360 said:

Well several years ago, while building a house on a slight hill, in the middle of a plowed corn field, we had a similar crane to set beams. Unfortunately it didn't have enough reach to set a particularly heavy beam at the back of the house, from where the crane was parked on the gravel road driveway. So we had the crane hook up to the beam and with the boom all the way in and lowered the operater drove through the plowed field with the beam to the back of the house and reset the crane in the field on uneven plowed ground and we set the beam no problem. Now granted it was only a slight rise but there is no way another road crane could have navigate that terrain, would have got hung up immediately. Hell my pickup truck couldn't have even drove through that field, wasn't 4x4. Anyway crane had no problem at all, it was pretty cool to watch and I was surprised the operater even agreed to try it, I guess at $150 an hour he figured it was worth it. 

So even if it isn't done often it is doable, no other type of crane could have done that. He was definitely off-road. 

if you go back over what I wrote, a plowed field doesn't constitute rough terrain - it's merely soft, and again, it's the tyre pressures (matched hopefully obviously) to the pressure that the ground can support, that gives you a the difference between a truck based crane on high pressures and a rough terrain crane on lower pressures. You still won't be climbing hills that would cause the crane boom to crash into the hill before the front axle started to climb it, which is fundamentally the point i was trying to get across to gvo25 about the boom being too long on the model.

Loads on ground are all about pressures - the total weight doesn't matter. And if you don't believe me on that, think about what skyscrapers are built on and what the function of foundations is.

The difference between a crane on 50psi and your pickup on 50psi is pretty much nil in terms of sinking into the ground - it's the higher mass of the crane that results in much larger tyres than your truck. The only other bit in play is tractive effort, which you noted in the difference between your 2wd pickup vs the awd crane.

Edited by bonox
Posted
30 minutes ago, Milan said:

Speaking of a boom sticking out too much:

liebherr-lrt1100-conexpo17-bauforum24-tv

Newest Liebherr RT crane, shown here in retracted travel mode.

I'd say 42082 resembles this model the most. The lines fit.

Posted (edited)

Yes @bonox you are correct of course, wasn't really trying to start a debate on what constitutes rough terrain, just trying to point out why manufacturers would call this type of crane a rough terrain crane. Basically it can drive over terrain that most other cranes can't. Which you explained quite well, just wanted to add to it. 

Edited by Johnny1360

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