[REVIEW] 8043 - Excavator

[tomacwhite]

It's great that more people on here are starting to get the model.

I noticed something else with mine yesterday when I was playing with it. The middle structure of the arm (and middle linear actuator) seems to slow down when its reaching the end of its stroke, almost like its harder for the motor to drive the axle. Would this be due to the weight of the arm? If I remove the linear actuator and just spin the axle they work 100% perfectly.

[Silcantar]

It's great that more people on here are starting to get the model.

I noticed something else with mine yesterday when I was playing with it. The middle structure of the arm (and middle linear actuator) seems to slow down when its reaching the end of its stroke, almost like its harder for the motor to drive the axle. Would this be due to the weight of the arm? If I remove the linear actuator and just spin the axle they work 100% perfectly.

Might be leverage. If the arm is horizontal at that point, the torque exerted on it by gravity would be at its maximum.

[Fyredog]

Here are my 2 excavators side by side. I absolutely loved the build - I am impressed with the thought put into making the 6 functions operate off the 4 motors.

[tristan86]

I am having a problem with the main arm as well, it lifts so slow it is barely moving, it esentially doesn't move. Did anyone have this problem and fix it? I have seen videos of the model in action, and the arm seems to work fine.

[tomacwhite]

I am having a problem with the main arm as well, it lifts so slow it is barely moving, it esentially doesn't move. Did anyone have this problem and fix it? I have seen videos of the model in action, and the arm seems to work fine.

What I did to fix mine:

- I removed the two Linear Actuators which attach to the arm (at the Arm, not the Excavator end) and then screwed them in all the way equally, then back out all the way equally. This seemed to loosen them up a bit so the action was smoother. I think one of them was maybe sticky or something.

- Before I did this they looked equal to me but I don't think they were.

- After doing this the main arm raised much more smoothly.

[Jetro]

I did exactly the same with the two parallel LA's on the Front Loader. A small misalignment can cause enough friction to not let the arm operate properly.

[Countdown]

Being a civil engineer, I see these machines everyday (even drive them around when no one's looking :) )

Seeing both models side by side gives me the urge to get/build both models. Wondering if Fyredog did instructions or detailed photos of his build?

Fyredog's red excavator looks like the equivalent of a Komatsu PC400 and the 8043 more like a PC300 a 230. Personaly I prefer the red one as it looks more to scale and bulkier. What gives it away is the carrier's scale compared to the superstructure.

Good job!

-Nick

[Fyredog]

Thank you for you gracious words!

I am considering making a pdf style building plan which requires complete reverse dis-assembly with pictures to assemble. My fear is something going wrong on the way - I know mine so well though I think I could fix any issues. My temptation to change things along the way would be tremendous, never the less I may just do this - as I would love for any one to be able to build my interpretation.

Thanks again.

[Jurgen Krooshoop]

Just ordered my 8043 at Bickshop Holland for € 136 + € 7 shipping-cost. They have a discount-action for people who order & pay before 31 of July. Now I have to wait for about 2 more weeks for it to arrive ...

Edited July 28, 2010 by Jurgen Krooshoop

[darksheep]

Thank you for you gracious words!

I am considering making a pdf style building plan which requires complete reverse dis-assembly with pictures to assemble. My fear is something going wrong on the way - I know mine so well though I think I could fix any issues. My temptation to change things along the way would be tremendous, never the less I may just do this - as I would love for any one to be able to build my interpretation.

Thanks again.

That would be cool and we could then see what you did diffrent to lego :)

[jason-l]

Hello all - First post. I've been a lurker on this forum for a short while and found it very useful I was delighted to get this set earlier this week and just love it, one of the reasons being it is so compact and functional. It is my first Power Functions model.

I'm also having problems with the motor struggling to raise the main arm and have ensured the paired actuators are evenly matched. This has not solved the issue and closer inspection in the gearbox shows that when the clutches are engaged on the 'crane' side, some of the 'drive' side gears still turn/drag slowly. Stopping them with my finger reveals considerable drag/load.

For example, the 2nd motor from the left drives the main arm actuators pair and left tracks (left stick on remote). When the clutches fully engage to the crane actuator gears and I operate the main arm (left stick) the left tracks' drive gears sometimes turn/drag slowly. It's as if the clutch gear is dragging on the spinning shaft? Is this a common occurrence? Anybody else seeing the same in their 8043's gearbox? I'm having a similar issue with the track drives - the right tracks (using the outer, clutch drive through the turntable) have much less power.

I think I need to dissasemble to solve this

During assembly, I am always very careful to ensure all gears/shafts spin freely.

[Buffalo]

First post from me as well.

I bought my 8043 from TRU the first day it was listed there, and I'm completely satisfied with it. I modified the gearbox so that the motors drive the treads, the superstructure rotation and the boom, removing the clutches and drive rings. I added a third IR receiver in the empty space in the gearbox area, and mounted 2 M motors in the boom to power the stick and the bucket. I have 3 remotes so I can run all 6 functions without changing gears. I've built a flatbed trailer for it, and am waiting for a couple Bricklink orders to come in so I can build a dump truck to pull it.

I also wired up an adapter to connect a 9.6V NiMH RC battery pack to the excavator's electrical system and slightly modified the battery compartment area so the pack sits level on the superstructure's deck.

Jason: I've noticed that some of the driving ring extensions that came with my excavator fit a bit too tightly on the axles and can cause noticeable drag, so that may be the problem. My gearbox doesn't have any driving rings or extensions mounted and my linear actuators are aligned correctly, but the motor still struggles to lift the boom, even with the extra grunt of an RC battery pack behind it. Of course in mine it's got to lift 2 M motors in addition to the normal weight of the boom, but it still works fine and can lift a bucket full of bricks with no problem

[jason-l]

Do you have any photos of your mods, Buffalo?

I'm going to disassemble so check the friction of the drive ring extensions on shafts - make sure they spin freely. There are a LOT of gears for those motors to turn!

[Buffalo]

Do you have any photos of your mods, Buffalo?

I'm going to disassemble so check the friction of the drive ring extensions on shafts - make sure they spin freely. There are a LOT of gears for those motors to turn!

I'm amazed the model works at all considering the complexity of the drivetrain, not to mention the amount of weight and force it's got to deal with. Something else you might try is to make sure all the connections between subassemblies are aligned and attached perfectly. The weight of the boom in front and the battery box behind might be distorting the frame slightly and binding the gearbox.

I don't have any pictures of my mods, but I will post some later today along with some LDD mockups of the gearbox.

[Fyredog]

I have noticed that anytime you pair 2 linear actuators together using one m-motor you will have significant drag and loss of power. My 8421 Mobile crane uses 2 linear actuators to raise it's boom, I had to use a XL motor for the torque to raise and lower the boom with no effort. The M-motors don't seem to have near the torque. My red excavator was geared differently to handle the extra added weight of my boom as it is bigger than the 8043. I just compared the 2 on raising the main boom. My 8043 does seem to struggle, but it still works fine. My red excavator seems to work better, but slower in action on all boom parts. My red excavator is faster in drive than the 8043, but slower on slew than the 8043. You have to admit though for all that is happening with the 8043 it is an amazing piece of work from Lego!

Edited July 30, 2010 by Fyredog

[Buffalo]

I have noticed that anytime you pair 2 linear actuators together using one m-motor you will have significant drag and loss of power.

If only there was enough room for an XL motor in the bowels of 8043. It seems like when 2 LAs are connected in parallel like that they want to fight each other if they're even slightly out of alignment.

[flyz]

Ordered mine off TRU and I hope it comes in a few days :D

[tomacwhite]

This has not solved the issue and closer inspection in the gearbox shows that when the clutches are engaged on the 'crane' side, some of the 'drive' side gears still turn/drag slowly. Stopping them with my finger reveals considerable drag/load.

For example, the 2nd motor from the left drives the main arm actuators pair and left tracks (left stick on remote). When the clutches fully engage to the crane actuator gears and I operate the main arm (left stick) the left tracks' drive gears sometimes turn/drag slowly. It's as if the clutch gear is dragging on the spinning shaft? Is this a common occurrence? Anybody else seeing the same in their 8043's gearbox?

I get exactly the same issue as you.

When operating the lift, you can see the drive gears for the track slowly spinning too. Very strange.

My main arm raises OK now, but the middle part is slow and sounds like the motor is struggling. However if I disconnect the arm so just the axle is spinning the motor runs perfectly smoothly with no lag.

Edited July 30, 2010 by tomacwhite

[tomacwhite]

It would be really good to see others peoples models in action, specifically focused on what the gearbox is doing. There is definitely some dragging of gears going on from the motors secondary function (ie the Left track gear is slowly moving when raising the arm

etc).

Raising the arm is all slow again now but not sure if the alkalines are getting exhausted!

[CP5670]

For example, the 2nd motor from the left drives the main arm actuators pair and left tracks (left stick on remote). When the clutches fully engage to the crane actuator gears and I operate the main arm (left stick) the left tracks' drive gears sometimes turn/drag slowly. It's as if the clutch gear is dragging on the spinning shaft? Is this a common occurrence? Anybody else seeing the same in their 8043's gearbox?

I don't have this model yet, but this does sometimes occur with the idle gears if the geartrain is very smooth. One way to fix it is to add a very small amount of friction to the geartrain by adding a rubber belt or extra gears somewhere. I did this sort of thing here, for example. (the 1x1 round plate rotates freely, but the rubber belt's tension is enough to keep the gear still when it's not engaged)

[menad]

Thats a great review for a phantastic well created Technic set! Thanks Blakbird! It is truly the king of the official construction machines in Lego Technic. The gearbox is very clever and it is automated what we never seen before in an offical set. Last year when building the 8258 gearbox I can't imagine that TLG will improve the gearbox technic so soon. Thats very good that the sets are going more and more complex. This one is in the top of power functions. The design is also very impressive. I think it is much more complex than the 8275 bulldozer.

I hope TLG continue improving the PF system and next year we get a complex pneumatic backhoe with PF compressor or a supercar.

[flyz]

Received my set today and I was excited to start building it. I promptly (bad idea) went through the whole building process and had a complete excavator in a matter of hours. When I finally put some batteries in, I discovered a huge mistake on my part. The excavator wouldn't slew! So I did a bit of investigation and found out that I've built the whole thing with the turntable upside down!

With the whole set pretty much build around the turntable, I couldn't find a way of fixing the problem without taking the whole thing apart. I guess this is an excuse to build the B model.....

Edit: I've now completed the B model and there's huge amounts of spare parts. Stuff like panels, 3L universal joints, the entire gearbox components and tons more. The model a lot less complex but all the functions are great. I think I prefer this one after building both.

Edited August 4, 2010 by flyz

[tomacwhite]

Does anyone know where to get the inventory for the B-Model? I think I might have nearly enough pieces to build it without taking apart the A-Model, but I am not sure. It's not at the back of the B-model manual.

[Blakbird]

Does anyone know where to get the inventory for the B-Model? I think I might have nearly enough pieces to build it without taking apart the A-Model, but I am not sure. It's not at the back of the B-model manual.

The inventories posted in the instructions are always for everything in the box, often even including the extra parts. So you can't tell from the inventory what you need for the B-model. I often make inventories from LDraw files, but of course you have to model the whole thing in LDraw first!

[tomacwhite]

How long are peoples batteries lasting with this model? It seems to be really struggling now, yet the the set hasn't been used much at all. The 8275 Bulldozer is on its original set of batteries and is still moving perfectly. The Excavator is struggling with main arm and boom movement (VERY slow), and slewing which is crawling now.