8043 Excavator - Lego update

[Andy D]

Use Customer Service, post form and wait to recieve call from lego.

Thanks for the link! Now just waiting for LEGO service pack to assemble the model.

Andy D

[Lyle]

Hi,

I bought 8043 a couple of weeks ago and I’m experiencing issues, like many users here it seems. I built the set as carefully as I could and chose rechargeable batteries for it. It took me nearly 2 days to fully load the 12 batteries before starting to use the excavator. At the very beginning, everything seemed to work fine. Maybe the arm moved up a bit slowly, but the motor didn’t make that “struggling” noise I expected. Problems arose soon, though, I’d say after about 15-20 minutes, with some of the movements becoming slower and slower. Now one track is much slower than the other and the worst is, the motor assigned to the gear no longer has the minimum power required to operate, which means I cannot even gear the other motors to activate the arm…

And now I’m reading the set was kind of faulty right from the start! I must be humble, because I’m not a very experienced TECHNIC builder (I must have bought 4-5 sets of it in my life) and maybe there were a few things inaccurate in the way I put up this set (although I did pay attention to smooth spinning / reducing friction). Yet, I very quickly had the intuition there would be a problem with this set. To me, the motors are simply not powerful enough, regardless of how skilful a builder you are. There’s far too much strain in the clocks… and TLG designers were very clever (the gearbox is and will always be marvellous) but also overambitious in my opinion. When spinning some of the gears with my fingers during the construction I thought, several times “if those motors are powerful enough to make THIS work for hours, then the 9V Lego motors’ efficiency must have improved significantly since I bought one of those 9V trains back in the 80s”

Now here’s the important question, and maybe some of you can help. In my case, what do you think is to blame? The batteries? The motors? Me  ? And above all, are 20 minutes of use enough to damage some of the motors or is it just the batteries I need to recharge? This is topical question as I bought this set precisely because it features 4 motors I’d like to use in MOCs and there’s no way I’m keeping them if they’re already damaged, presumably by TLG’s fault. If the batteries are the problem, I can just take the set apart and keep all this already valuable equipment (I got the set in a shop in Luxembourg for €140, which is fair). Actually this is a bit of a dilemma for me. For those of you who had issues too, what did you guys decide? Thanks for your advice.

Edited August 25, 2010 by Lyle

[Parax]

Since it has not been posted here yet:

Dear LEGO Technic Fan,

You recently ordered our LEGO Technic Motorized Excavator 8043.

In the last few days we have received calls and emails from consumers reporting that this set doesn’t meet the high standards they expect from our products.

Our Quality team have investigated and it appears that the digging arm itself (specifically the ‘linear actuator’), which works perfectly well in our other sets, is not strong enough to lift the arm of our Motorized Excavator 8043. The piece itself is not faulty or unsafe, but gets too strained in combination with all the gear-wheels used in this particular set.

We are extremely sorry that this has happened and realize how disappointed the LEGO builder in your household will be. We are usually so proud of the quality of our models and know that when you buy a LEGO set you expect it to be 100% reliable.

Of course you have the option of returning the set for a full refund or credit with Shop @ Home. If you’d like to do that, please get in touch with us (either through Customer Service as normal or by replying to this email) and let us know.

However, we also realize that this is a unique set and so you might not want to return it, you just want it to work properly. Because of this, we have created a second option: We are having a new replacement part made which we will send to you as soon as it’s ready. We’ve only just started the design and production of this new piece, so it may not be available until early October.

In the meantime, if you choose not to return your set but to wait for the replacement piece, we'd like to offer you a GBP 10.00 credit with our apologies and we will send the new part as soon as possible. Again, please can you reply to this email to let us know what you'd like to do?

With our apologies once more,

Your LEGO Customer Service team.

"(specifically the ‘linear actuator’)"

"We’ve only just started the design and production of this new piece"

Now that does sound good!

P.

[Blakbird]

I'm very interested to know how they "fixed" the linear actuator. As they stated, there is nothing wrong with it for normal use, but it is not suited for "heavy duty" applications. In this case, there are already 2 actuators in parallel which reduces the load on each, though the load on the motor stays the same.

The fact that the blame is being placed on the LAs suggests that they are being "damaged" in some way by repeated use. Who wants to tear one of them apart and see what has happened inside?

Since the new actuator will be different in some way, I wonder how LEGO will make it visually distinguishable? We'll need to be able to tell the difference between the old and the new part. Or, like the old 9V actuators, they may just make an improvement and then make all new parts to the new standard. You can tell the difference between old and new with a careful examination, but it is not immediately obvious.

I also wonder if they will just send 2 new actuators to lift the boom, or whether they will replace all 4.

Finally, what is the actual fix? An all metal internal design would be a huge improvement, though it would probably need to be lubricated on assembly.

[allanp]

PS @Allan, Race car tires are wider because for several reasons, rubber is flexible and this is key to grip, the thinner the better (more flexible) so lower pressure and wider helps, as the tire deforms onto the roughness of the road this provides 'keying' grip rather than true friction, in addition tires are 'sticky' and race tires even more so, so you want greater area for the sticky to apply, and to go further tires leave small amounts of rubber behind when loaded this rubber is torn away in a shear situation from the tire, you would loose grip faster with small contact area so a larger surface means a greater shear surface, but this is about the elasticity of the rubber and its tearing strength again not really true friction.

Ahhhhhhh now I get it. Thanks

[allanp]

I'm very interested to know how they "fixed" the linear actuator. As they stated, there is nothing wrong with it for normal use, but it is not suited for "heavy duty" applications. In this case, there are already 2 actuators in parallel which reduces the load on each, though the load on the motor stays the same.

I suppose they could have used a finer thread (making it even slower and cause problems when using an old one with a new one in tandem like in the 8043 and the wheel loader ), added lubrication (posibbly making it more expensive ) or used all metal parts (which would deffinately make it more expensive )

The fact that the blame is being placed on the LAs suggests that they are being "damaged" in some way by repeated use. Who wants to tear one of them apart and see what has happened inside?

I would, don't mind losing an LA, but I decided against buying the 8043.

Since the new actuator will be different in some way, I wonder how LEGO will make it visually distinguishable? We'll need to be able to tell the difference between the old and the new part. Or, like the old 9V actuators, they may just make an improvement and then make all new parts to the new standard. You can tell the difference between old and new with a careful examination, but it is not immediately obvious.

My guess is it will look the same.

I also wonder if they will just send 2 new actuators to lift the boom, or whether they will replace all 4.

I'm sure I read somewhere that it will be all four.

Finally, what is the actual fix? An all metal internal design would be a huge improvement, though it would probably need to be lubricated on assembly.

I somehow doubt it will be a swapping from one material to the other (weather it be metal or some other, tougher plasic) because in one e-mail posted in this thread, they said they had re-designed the LA. So maybe it's a finer thread (increasing the gearing down so to speak) or allowing a bigger tolerance for lubrication, or perhaps adding somthing like a PTFE washer inside the bottom to reduce friction as it turns. Hmmmmm.

[Parax]

I suppose they could have used a finer thread (making it even slower and cause problems when using an old one with a new one in tandem like in the 8043 and the wheel loader )

Not strictly the case that it will be slower, if they use the same Pitch, but a finer thread it can work the same (you can have two threads per turn instead of one - one turn moves you two half width threads) so it will respond exactly the same, extension per turn, but still have twice the contact pad area. (I think this would need metal though!)

My guess is it will look the same.

If they are heavy duty LA's, I'm hoping for a grey reversal. or at least a colour change (orange to red?) on the axle insert.

I'm sure I read somewhere that it will be all four.

I think it will be just the two that lift the arm, the others work well as they are.

I am a little surprised they are considering a new LA (not disappointed though!) as the gearing change (8t+32t) on the lifting actuators does make a significant improvement. I'd recommend it! and because this change works so well, so I am left thinking that the Actuator change could just be a weaker clutch to prevent stalling the motors?

P.

[eMHa]

Hi,

[..]

Since the new actuator will be different in some way, I wonder how LEGO will make it visually distinguishable? We'll need to be able to tell the difference between the old and the new part. Or, like the old 9V actuators, they may just make an improvement and then make all new parts to the new standard. You can tell the difference between old and new with a careful examination, but it is not immediately obvious.

I hope they will make a different color scheme.

I also wonder if they will just send 2 new actuators to lift the boom, or whether they will replace all 4.

In this thread it was told TLG will send replacement 4 LAs! I think it's very complicated for TLG to do damage limitation. On one side they have to admint some fault, on the other side they have to keep the basic things in the set the low cost to keep. So my opinion is that the LAs have a great impact on the malfunction and are easily to replace. No new building instructions, no new sets, they only have to exchange the LAs in the already produced boxes and they can easily produce and deliver these Service Bag.

I would say that what TLG is doing now is technically not optimal, but economically AND technically in sum optimal.

As we can see in this thread there're also a lot of other possibilities to improve the functioning of the set. For sure, the designers don't have the time to create and test each possibility.

Finally, what is the actual fix? An all metal internal design would be a huge improvement, though it would probably need to be lubricated on assembly.

It's also possible to coat (?) the inner plastic with metal. Hasn't TLG some parts in chrome? I don't know if chrome would be sufficient for this. But the friction for metal on metal will be much lesser than metal on plastic.

Just my thoughts about this.

[imajor]

I'm very interested to know how they "fixed" the linear actuator. As they stated, there is nothing wrong with it for normal use, but it is not suited for "heavy duty" applications. In this case, there are already 2 actuators in parallel which reduces the load on each, though the load on the motor stays the same.

What if they simply attach a spring to the LAs? So that part of the weight is handled by the spring? Then it would be easier for the motor to lift the arm, since part of the lifting would be done by the spring.

[rgbrown]

The fact that the blame is being placed on the LAs suggests that they are being "damaged" in some way by repeated use. Who wants to tear one of them apart and see what has happened inside?

Possibly ... I'd also be quite interested in this result. Seems the some of the anecdotal evidence here suggests that this is the case, while some suggests it isn't.

My opinion is that it is the LAs fault, but only because there is simply too much friction at high load and the M-motors can't cope with the power dissipation required to move them, i.e. the LAs are at fault, but it is the motors that are dying. This could also just be considered a design flaw.

[Blakbird]

It's also possible to coat (?) the inner plastic with metal. Hasn't TLG some parts in chrome? I don't know if chrome would be sufficient for this. But the friction for metal on metal will be much lesser than metal on plastic.

Chrome plating doesn't add any strength, it is only a wear coating. Chrome is exceptionally brittle, so if put over a ductile material like ABS, nylon, or Teflon, it would simply crack and flake off as the substrate deforms.

[Daniel-Technic]

I chose to do a little investigation of my own so see if indeed the M-motors are to blame, because I simply do not believe The Lego Group would mass-produce a product that wouldn't work- if the designer of 8043 said that the M-motors should take the pressure, then they have to- that they do it less efficiently than the XL motors, that's a whole other story. So, after fighting my way through the internals of the excavator I made a discovery most sinister. Two grey 16-tooth gears transfer the power from the far left motor (if you face the excavator from the back) to the left-hand tracks. One of these gears are held by a tan pin that is not secured by the bottom, so it will slide out eventually with time. It explains why when I first built it, it ran well, and got progressively worse. What I did was basically remove the tan pin and the grey shaft from the second gear and replaced the tan pin with a size 3 shaft and the grey shaft (from the second gear) with a size 6 shaft. All is left is to secure the bottom. This mod was based on Jurgen's modifications of 8043 (see his Ultimate 8043 post, it is magnificent work). The result was fantastic performance from the left track, and the excavator's speed increased dramatically as well, since both tracks move at the same speed without any strain. This is worrying however, because this is a design flaw that can result in gear/motor damage if left unchecked.

That a useful info. I will give it a go and will test it again, I love taking it again and rebuild.

My excavator will now not lift the main boom anymore, think the batteries has ran out. The bucket, second boom, turntable, right track and gear switch still work, left track hardly move at all, only move if right track moved as well.

Daniel.

[CP5670]

I'm very interested to know how they "fixed" the linear actuator. As they stated, there is nothing wrong with it for normal use, but it is not suited for "heavy duty" applications. In this case, there are already 2 actuators in parallel which reduces the load on each, though the load on the motor stays the same.

The fact that the blame is being placed on the LAs suggests that they are being "damaged" in some way by repeated use. Who wants to tear one of them apart and see what has happened inside?

Since the new actuator will be different in some way, I wonder how LEGO will make it visually distinguishable? We'll need to be able to tell the difference between the old and the new part. Or, like the old 9V actuators, they may just make an improvement and then make all new parts to the new standard. You can tell the difference between old and new with a careful examination, but it is not immediately obvious.

I think there is in fact a basic flaw in the LA design, even in other sets. They have too much friction compared to an equivalent mechanism using just worm gears, at least in their "degraded" state. You would expect the opposite; the LAs should outperform worm gears given that they are specifically designed for this purpose.

TLG will probably just shift to the new revision in this particular set, and future copies of other sets with LAs. They have done part revisions many times before and the changes have almost never been obvious on the outside. This can create problems with sites like Bricklink, which don't always list the revisions as separate pieces.

[rgbrown]

I think there is in fact a basic flaw in the LA design, even in other sets. They have too much friction compared to an equivalent mechanism using just worm gears, at least in their "degraded" state. You would expect the opposite; the LAs should outperform worm gears given that they are specifically designed for this purpose.

Yes ... who has an 8295 (telehandler?) I was very surprised at the effort required to raise the boom on that given how geared down it was. Didn't feel very "technic" to me

[Blakbird]

Yes ... who has an 8295 (telehandler?) I was very surprised at the effort required to raise the boom on that given how geared down it was. Didn't feel very "technic" to me

The 8295 linear actuator is indeed very hard to turn, but part of that is due to the fact that when it has the greatest load to lift (when the arm is all the way down and fully cantilevered), the mechanical advantage of the LA is almost nothing because it is nearly parallel to the boom with only a 1 stud moment arm. The mechanical advantage gets better and the boom goes up, and the load on the LA also goes down at the same time because when the boom is raised, a greater portion of the weight is taken by the pivot axle instead of the LA (the fulcrum).

[CP5670]

Yes ... who has an 8295 (telehandler?) I was very surprised at the effort required to raise the boom on that given how geared down it was. Didn't feel very "technic" to me

I had the same impression with the 8265 Front Loader when I first got it. At the time, I assumed it was because of the relatively complex geartrain, but upon further inspection (after people started to discuss these issues) the gears actually move very smoothly if the LAs are disconnected. A close comparison is 8862, which has the same functionality on the front bucket, and it works effortlessly compared to 8265.

Blakbird has a good point about the orientation of the LA though. That issue affects this model too.

Edited August 25, 2010 by CP5670

[menad]

I'm curious about if we can get the Service Pack for 8043 in regular shops? What do you think? Or we can just by it through Shop at Home.

Edited August 26, 2010 by menad

[Routemaster]

I'm curious about if we can get the Service Pack for 8043 in regular shops? What do you think? Or we can just by it through Shop at Home.

I think you can get it only through Lego Customer Service. It's a free part and you can contact them through a free call.

[Stephan]

I think you can get it only through Lego Customer Service. It's a free part and you can contact them through a free call.

BUT do you think TLG will 're-release' this 8043? And then I mean WITH the replacement part...

I hope so!

[AndyC]

BUT do you think TLG will 're-release' this 8043? And then I mean WITH the replacement part...

I hope so!

I would expect so, it'd be a very costly businness if they didn't. Anyway, I got my email yesterday, so I guess now it's just a case of wait and see.

[atarist]

A phonecall later:

Lego tells me, that they change the LA's.

Lego is engineering a whole new LA that can pull up the heavy main arm. The M-motors will not changed.

To get the new peaces, contact lego with a phonecall and register your datas. They will send u the new parts as well soon, no costs for shipping.

Regards,

atarist

[nico71]

The 8295 linear actuator is indeed very hard to turn, but part of that is due to the fact that when it has the greatest load to lift (when the arm is all the way down and fully cantilevered), the mechanical advantage of the LA is almost nothing because it is nearly parallel to the boom with only a 1 stud moment arm. The mechanical advantage gets better and the boom goes up, and the load on the LA also goes down at the same time because when the boom is raised, a greater portion of the weight is taken by the pivot axle instead of the LA (the fulcrum).

The problem also with the 8295 gear is that lego uses 12t simple bevel to pass the torque and enable the rotation of LA, so the axle which turns is stressed (http://www.setechnic.com/Images/NoticesP/8295/059.jpg). Lego has solved this problem after with using a new type of bevel gear : the 20t simple bevel without cross. Then they can turn freely. But the arm of the excavator is really big, and even with this trick, they don't work good.

[dr_spock]

Lego Customer Service seems to be really quick. I submitted an online email through Lego.com site and not more than 15 minutes later I get a reply saying I'm on the list to receive new parts. It looked like the same canned reply everyone has been getting. It's still fun driving the 8043 around although I've stopped playing with arm.

[moebiusfactor]

Recently I've been having a bad superstructure slewing problem. I imagined once again it may be a gear issue or even the M-motor itself. It turns out that (sometimes, not always) the batteries are to blame. As we all know, 8043 is a thirsty little thing- it eats power like no tomorrow. And since the M-motors are not that powerful in the first place, the slightest drop in amperage from the batteries will cause them to be sloppy in their performance. I tried using the 8878 rechargeable battery I've been using in my TAS batmobile- not only the superstructure spinned a lot faster, but the overall performance of the M-motors was indeed far better. And, just got an email from Lego, it says the parts (4 LAs) will be sent out early October to all customers with the 8043 set.

[Frequency]

I chose to do a little investigation of my own so see if indeed the M-motors are to blame, because I simply do not believe The Lego Group would mass-produce a product that wouldn't work- if the designer of 8043 said that the M-motors should take the pressure, then they have to- that they do it less efficiently than the XL motors, that's a whole other story. So, after fighting my way through the internals of the excavator I made a discovery most sinister. Two grey 16-tooth gears transfer the power from the far left motor (if you face the excavator from the back) to the left-hand tracks. One of these gears are held by a tan pin that is not secured by the bottom, so it will slide out eventually with time. It explains why when I first built it, it ran well, and got progressively worse. What I did was basically remove the tan pin and the grey shaft from the second gear and replaced the tan pin with a size 3 shaft and the grey shaft (from the second gear) with a size 6 shaft. All is left is to secure the bottom. This mod was based on Jurgen's modifications of 8043 (see his Ultimate 8043 post, it is magnificent work). The result was fantastic performance from the left track, and the excavator's speed increased dramatically as well, since both tracks move at the same speed without any strain. This is worrying however, because this is a design flaw that can result in gear/motor damage if left unchecked.

It is interesting someone mentioned a drivetrain flaw which i think is addressed in Mr Krooshoop's "ultimate 8043" designs where a drive gear is held only by a tan half pin/axle (not sure of the correct description for this part)

anyway I was remarking to one of my friends today who is also waiting to buy the 8043 (we were going to get it late here in NZ anyway) about this and by chance he had handy a 8265 which we both own copies of

http://www.eurobricks.com/forum/index.php?showtopic=45259

this gear with similar building technique can be seen close up in the last picture of the first post in the review as i recalled that these were on the drivetrain that operates the LAs to work the loader

To my surprise the 16 tooth gear had HALFWAY worked itself off of the pin from the load caused by normal play with this function so still just enough to still mesh with both other gears (the other side is unable to do this due to placement of 2L friction pin w/ stop that attaches the steering)

I suppose where i am heading with this is that i am surprised that TLG would consider this an acceptable building technique in both 8265 and 8043 given that it could cause gears to strip their teeth if it were to work itself loose?

and also as a side not people may want to check their 8265s too

edit: found the post i was thinking of

Edited August 27, 2010 by Frequency