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8043 Excavator problem


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#1 DarkShadow73

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Posted 02 July 2012 - 11:38 PM

Hi - I am having a real problem with my 8043 Excavator.  On the remotes you have the ability to changeover with the red switch from the movement to the digging functions.  When I go to changeover from one function to another I cannot get the gearbox to changeover, it catches in the middle(neutral position) or won't fully engage each set of functions.  I believe it has something to do with the yellow gearknob wheels, they are really tight in turning even by hand pushing on them.  I hate to take the whole thing apart, and I carefully assembled it.  Anybody else have this problem?  It got me so mad last night I always smashed it against the floor.  I've changed to fresh batteries in both the battery box and remotes, but no change, its almost like the whole assembly attached to the gearbox is too tight or something.  I tried loosening it up, but no difference.  I can see the IR receivers are fully lit and blinking slightly as I try to engage one end or another and upon looking at the directions, I do have the channels aligned correctly.  I never considered this a problem as the functions work fine on either side.  I can get it from one function back to neutral position, but then it just like sticks and will engage partially, but not fully enough to do either function without forcing the gear knob wheels by hand, which is kind of ridiculous for a fully functional RC model.  Any ideas or suggestions appreciated.  

I don't have this problem with the 'b' model track loader, its been built for a couple years, but I don't believe if I recall, don't have it next to me, the remotes don't have a changeover between tracking and the shovel functions.

BTW, this is the original release, but the only issue with that was the LA's and I did replace the LA's with the new lubed ones, but that really doesn't apply to this problem anyway.  

Thanks, Eric

#2 Conchas

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Posted 02 July 2012 - 11:47 PM

View PostTechnicFreak, on 02 July 2012 - 11:38 PM, said:

Hi - I am having a real problem with my 8043 Excavator. On the remotes you have the ability to changeover with the red switch from the movement to the digging functions. When I go to changeover from one function to another I cannot get the gearbox to changeover, it catches in the middle(neutral position) or won't fully engage each set of functions. I believe it has something to do with the yellow gearknob wheels, they are really tight in turning even by hand pushing on them. I hate to take the whole thing apart, and I carefully assembled it. Anybody else have this problem? It got me so mad last night I always smashed it against the floor. I've changed to fresh batteries in both the battery box and remotes, but no change, its almost like the whole assembly attached to the gearbox is too tight or something. I tried loosening it up, but no difference. I can see the IR receivers are fully lit and blinking slightly as I try to engage one end or another and upon looking at the directions, I do have the channels aligned correctly. I never considered this a problem as the functions work fine on either side. I can get it from one function back to neutral position, but then it just like sticks and will engage partially, but not fully enough to do either function without forcing the gear knob wheels by hand, which is kind of ridiculous for a fully functional RC model. Any ideas or suggestions appreciated.

I don't have this problem with the 'b' model track loader, its been built for a couple years, but I don't believe if I recall, don't have it next to me, the remotes don't have a changeover between tracking and the shovel functions.

BTW, this is the original release, but the only issue with that was the LA's and I did replace the LA's with the new lubed ones, but that really doesn't apply to this problem anyway.

Thanks, Eric


It seems a very similar problem to what I had, when I first built this model.
It was everything correct and I only got it fixed, when I exchange the position of the motor that controls the changeover, with one in the remaining positions. Somehow it seemed to me that one of the motors was under-performing and was not strong enough to cope the torque required for the changeover.
After that I never had the same problem again.


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#3 Alasdair Ryan

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Posted 02 July 2012 - 11:51 PM

Have you cheacked to see of the grear change levers are in line with each other and that their is nothing stopping it from changing function's.:classic:
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#4 skylinedan

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Posted 03 July 2012 - 12:35 AM

Wonder if it timed right ? Could be your a tooth off somewhere between the slide collar and the motor. Does it go one way , but not the other ?

Edited by skylinedan, 03 July 2012 - 12:36 AM.


#5 Lemelisk

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Posted 03 July 2012 - 03:47 AM

In the instructions step 35 it shows a blue axle pin connecting to the yellow knob gear axle. If you replace it with a tan axle pin, the gearbox should shift much better. The surgery required for such a change may be difficult.

#6 Saberwing40k

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Posted 03 July 2012 - 05:22 AM

View PostLemelisk, on 03 July 2012 - 03:47 AM, said:

In the instructions step 35 it shows a blue axle pin connecting to the yellow knob gear axle. If you replace it with a tan axle pin, the gearbox should shift much better. The surgery required for such a change may be difficult.
Yep, but if you are takin' it apart this far, try switching the 2 16z gears with one 8z and one 24z gear. For best results, the 8z gear should be on the shaft going to the motor, and the 24z gear should be on the changeover shaft. I did this with mine when I was building it, as I had read the review beforehand and anticipated the problem.
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#7 hoeij

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Posted 20 August 2012 - 03:27 AM

View PostLemelisk, on 03 July 2012 - 03:47 AM, said:

In the instructions step 35 it shows a blue axle pin connecting to the yellow knob gear axle. If you replace it with a tan axle pin, the gearbox should shift much better. The surgery required for such a change may be difficult.

There is another friction pin (a longer one) on the other side.  That pin has a huge amount
of friction.

I did not put it in since I don't see the point of having friction on an axle
that is connected to a motor.  This way, function switching takes much less force.

#8 dhc6twinotter

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Posted 20 August 2012 - 04:35 AM

Eric, maybe you can try replacing the motor for the changeover mechanism with a different motor.  Might be having some problems with the motor.  

I second Alasdair Ryan's suggestion as well.

I'm not a huge fan of the changeover mechanism on 8043.  A clutch gear somewhere in there would have been really nice to keep the motor from stalling.

#9 Lost_In_Noise

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Posted 20 August 2012 - 05:33 AM

View PostTechnicFreak, on 02 July 2012 - 11:38 PM, said:

Hi - I am having a real problem with my 8043 Excavator.  On the remotes you have the ability to changeover with the red switch from the movement to the digging functions.  When I go to changeover from one function to another I cannot get the gearbox to changeover, it catches in the middle(neutral position) or won't fully engage each set of functions.  I believe it has something to do with the yellow gearknob wheels, they are really tight in turning even by hand pushing on them.  I hate to take the whole thing apart, and I carefully assembled it.  Anybody else have this problem?  It got me so mad last night I always smashed it against the floor.  I've changed to fresh batteries in both the battery box and remotes, but no change, its almost like the whole assembly attached to the gearbox is too tight or something.  I tried loosening it up, but no difference.  I can see the IR receivers are fully lit and blinking slightly as I try to engage one end or another and upon looking at the directions, I do have the channels aligned correctly.  I never considered this a problem as the functions work fine on either side.  I can get it from one function back to neutral position, but then it just like sticks and will engage partially, but not fully enough to do either function without forcing the gear knob wheels by hand, which is kind of ridiculous for a fully functional RC model.  Any ideas or suggestions appreciated.  

I don't have this problem with the 'b' model track loader, its been built for a couple years, but I don't believe if I recall, don't have it next to me, the remotes don't have a changeover between tracking and the shovel functions.

BTW, this is the original release, but the only issue with that was the LA's and I did replace the LA's with the new lubed ones, but that really doesn't apply to this problem anyway.  

Thanks, Eric

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#10 RideFire

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Posted 20 August 2012 - 07:11 PM

View PostLost_In_Noise, on 20 August 2012 - 05:33 AM, said:

I read

This post is about problems about the LA.  I myself have just carefully built the excavator and I'm having a lot of problems with the change over.  I have replaced the the blue friction pin with the tan frictionless pin that come as an extra piece.  I have replaced the yellow cog wheel like gears with two bevel gears ( I believe one is 12 tooth and the other is 24 tooth) so that I generate more torque yet I still have problems.  

I can go to the 'boom' controls just fine, no problems at all, but it struggles to go to the 'track' controls.  I took the motor out and manually tried to change over the gear.  It still catches and I just can't see what is stopping the clutch gears from engaging, especially since it has no problems going to the boom controls even before I made any adjustments.  I'm convinced its not a motor on a battery issue.  I have stripped the back of the tractor apart to see if I could see anything causing the problem but while operating the tractor with missing pieces beams start to loosen up.  So I'm scratching my head on this one.  I will say after making the adjustments I mentioned, it has improved to about almost 50 percent of the time engaging, but still its annoying.  I'm not sure what to do here.

#11 Hopey

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Posted 20 August 2012 - 09:54 PM

View PostLemelisk, on 03 July 2012 - 03:47 AM, said:

In the instructions step 35 it shows a blue axle pin connecting to the yellow knob gear axle. If you replace it with a tan axle pin, the gearbox should shift much better. The surgery required for such a change may be difficult.

I recently built my 8043 again after buying a can of silicon lubricant. I used a brush to put some on the teeth every gear and in every hole that a rotating axle goes through. (This seems to have worked ok, but honestly there doesn't seem to be that much difference)

I also lubricated the changeover sleeves and used a tan frictionless pin instead of a blue one. It turns out this was a mistake.

The changeover mechanism is so low in friction that when you let go of the red lever on the remote, the tension in the gear train is enough to pop it back out. I.e, in order to use a function (boom or track) reliably, I have to hold the red lever in the appropriate direction. As soon as I let go, it bounces back to neutral, or even over to the other function.

So I'm guessing they had a reason for using a blue pin there.

#12 RideFire

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Posted 20 August 2012 - 10:29 PM

View PostHopey, on 20 August 2012 - 09:54 PM, said:

I recently built my 8043 again after buying a can of silicon lubricant. I used a brush to put some on the teeth every gear and in every hole that a rotating axle goes through. (This seems to have worked ok, but honestly there doesn't seem to be that much difference)

I also lubricated the changeover sleeves and used a tan frictionless pin instead of a blue one. It turns out this was a mistake.

The changeover mechanism is so low in friction that when you let go of the red lever on the remote, the tension in the gear train is enough to pop it back out. I.e, in order to use a function (boom or track) reliably, I have to hold the red lever in the appropriate direction. As soon as I let go, it bounces back to neutral, or even over to the other function.

So I'm guessing they had a reason for using a blue pin there.

I read that whole that whole topic.  Im guessing the silicon + the frictionless pin was too much.  I noticed if I change to the tracks, if I move the left side tracks it throws the changeover into gear.

#13 hoeij

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Posted 21 August 2012 - 02:36 AM

View PostRideFire, on 20 August 2012 - 07:11 PM, said:

This post is about problems about the LA.  I myself have just carefully built the excavator and I'm having a lot of problems with the change over.  I have replaced the the blue friction pin with the tan frictionless pin that come as an extra piece.  I have replaced the yellow cog wheel like gears with two bevel gears ( I believe one is 12 tooth and the other is 24 tooth) so that I generate more torque yet I still have problems.  

I can go to the 'boom' controls just fine, no problems at all, but it struggles to go to the 'track' controls.  I took the motor out and manually tried to change over the gear.  It still catches and I just can't see what is stopping the clutch gears from engaging, especially since it has no problems going to the boom controls even before I made any adjustments.  I'm convinced its not a motor on a battery issue.  I have stripped the back of the tractor apart to see if I could see anything causing the problem but while operating the tractor with missing pieces beams start to loosen up.  So I'm scratching my head on this one.  I will say after making the adjustments I mentioned, it has improved to about almost 50 percent of the time engaging, but still its annoying.  I'm not sure what to do here.

The motor for the change-over function has to turn TWO friction pins, one of them being this one:
    Light Bluish Gray Technic, Pin Long with Friction Ridges Lengthwise and Stop Bush
(see http://www.bricklink...nv.asp?S=8043-1 for pictures).

That pin has friction in 2 holes.  It is hard to turn it by hand, so  I didn't
put it in during the build because it looked like a much too large burden for
the change-over motor.

Without the friction pins, the change-over is very fast.

#14 RideFire

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Posted 21 August 2012 - 03:18 AM

View Posthoeij, on 21 August 2012 - 02:36 AM, said:

The motor for the change-over function has to turn TWO friction pins, one of them being this one:
    Light Bluish Gray Technic, Pin Long with Friction Ridges Lengthwise and Stop Bush
(see http://www.bricklink...nv.asp?S=8043-1 for pictures).

That pin has friction in 2 holes.  It is hard to turn it by hand, so  I didn't
put it in during the build because it looked like a much too large burden for
the change-over motor.

Without the friction pins, the change-over is very fast.

Ahhh that has to be it.  Does lego make a no friction long pin with stop bush?  I noticed they're usually tan in color.  I have no friction long pins but this has been bugging me all day.  It is fairly stiff even with all of the adjustments I have made.  Thanks for letting me know what I was missing.

#15 hoeij

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Posted 21 August 2012 - 01:43 PM

View PostRideFire, on 21 August 2012 - 03:18 AM, said:

Ahhh that has to be it.  Does lego make a no friction long pin with stop bush?  I noticed they're usually tan in color.  I have no friction long pins but this has been bugging me all day.  It is fairly stiff even with all of the adjustments I have made.  Thanks for letting me know what I was missing.

This long friction pin is the gray pin that is inserted on page 12, step 44, of book 2.
You see a gray pin being inserted on top of the axle connected to a motor.

Then in step 46, this gray pin will go into 2 holes, and so it'll have a huge amount
of friction.  Function-switching will require lots of force this way, so I left
it out, and it works fine.

(PS.  There is of course also the blue friction pin on page 79, step 35, of book 1.
      This one will likely have less friction than the gray pin in book 2 because the
      gray pin has friction in two holes.  Still, there seems to be no good reason to
      have friction there, so I used something without friction instead).

Edited by hoeij, 21 August 2012 - 01:52 PM.


#16 Out of Sight

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Posted 21 August 2012 - 02:07 PM

What kind of batteries are u using? Alkalines are useless since they have a low discharge rates (despite higher voltage which will plummet LOW once serious current is extracted from them). I own the revised 8043 with the new LA's, I've only used high discharge rechargeable NiMH batteries for cameras which yield more consistent torque, haven't had single issue since Dec 2010  :classic: Changeover smoothly.

BUT, I did have temporary issue with the changeover 'springing back' to neutral once the lever reaches its full travel.
Here are few things you could try:
1. Electric motor usually "springs back" due to its magnetic pole..disassemble just the rear end, plug the motor out and turn it slightly and reattach. test it first
2. Appy a dab of silicone oil on the tan ribbed sleeves and the red driving rings, idk what parts number it is. This will aid the red driving rings to 'skip' between the ridges easier..hence less stress on the motor.

I kinda disagree swapping to frictionless pins, since the friction pins add as 'brakes' so the it won't shift to neutral easily.

Edited by Out of Sight, 21 August 2012 - 02:08 PM.

I'm having a nervous brick-down...

#17 hoeij

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Posted 21 August 2012 - 06:21 PM

View PostOut of Sight, on 21 August 2012 - 02:07 PM, said:

What kind of batteries are u using? Alkalines are useless since they have a low discharge rates (despite higher voltage which will plummet LOW once serious current is extracted from them). I own the revised 8043 with the new LA's, I've only used high discharge rechargeable NiMH batteries for cameras which yield more consistent torque, haven't had single issue since Dec 2010  :classic: Changeover smoothly.

BUT, I did have temporary issue with the changeover 'springing back' to neutral once the lever reaches its full travel.
Here are few things you could try:
1. Electric motor usually "springs back" due to its magnetic pole..disassemble just the rear end, plug the motor out and turn it slightly and reattach. test it first
2. Appy a dab of silicone oil on the tan ribbed sleeves and the red driving rings, idk what parts number it is. This will aid the red driving rings to 'skip' between the ridges easier..hence less stress on the motor.

I kinda disagree swapping to frictionless pins, since the friction pins add as 'brakes' so the it won't shift to neutral easily.

I'm using rechargeable AA batteries, so the nominal voltage of the battery box is 6 x 1.2 = 7.2 volts, and that works fine.
With both friction pins removed, my guess is that function switching will still work at a substantially lower voltage (i.e.
when the batteries are almost empty).

1. The "spring back" is a small effect because the M motor is geared down quite a bit internally.

2. Removing a friction pin has the same effect as applying lubrication; both reduce friction.  You picked one, I picked the other.
   If you lubricate those tan ribbed sleeves, then you probably do need to use a friction pin to keep
   it from going back to neutral.

I'm still wondering though why the lego designers chose to add friction.  Perhaps they were using driving rings + ribbed sleeves
that had already been used a lot, and that had much less friction than new ones.
The sliding friction between the driving rings and the ribbed sleeves, if that decreases over time when you use them a lot,
then it may be possible that at some point their friction becomes so low that I actually do have to put in a friction pin.
I don't expect that to happen, but if it does, I'll let you know.

#18 Kronos

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Posted 26 August 2012 - 07:34 PM

A little off topic, but I can't find the 8043 B-Model instructions anywhere.   :hmpf_bad: Could someone post the link please?

-Mike

#19 Alasdair Ryan

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Posted 26 August 2012 - 07:43 PM

Instruction download link from lego technic.
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#20 Kronos

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Posted 26 August 2012 - 08:14 PM

View PostAlasdair Ryan, on 26 August 2012 - 07:43 PM, said:



Thanks Alasdair!  I was looking in the wrong place @ LEGO.com.   :blush:

#21 hoeij

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Posted 27 August 2012 - 01:54 PM

View Posthoeij, on 21 August 2012 - 06:21 PM, said:

I'm still wondering though why the lego designers chose to add friction.  Perhaps they were using driving rings + ribbed sleeves
that had already been used a lot, and that had much less friction than new ones.

Yesterday I put some new AA rechargeable batteries (fully charged) in 8043,  these batteries
are more powerful than what I've used before.   With both friction pins removed in my 8043,
it function-switches so fast on those new batteries that when I switch to arm-operations, it
occasionally bounces back to neutral  (if I only touch the red control on the remote controller
for a very short time then it works OK).

It seems then that, if your batteries are very strong, then some amount of friction is helpful
to prevent bounce-back.  Perhaps using 1 friction pin instead of 2 would have been optimal.

#22 sama

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Posted 28 August 2012 - 08:21 AM

Does rechargeable batteries give you maximum performance? I was also wondering, would these new v2 ir receivers give 8043 better performance (because they get more power to the motors [ I have no clue with this technical electrical stuff])?
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#23 tewesy_81

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Posted 28 August 2012 - 08:49 AM

i say just redesign and build ur own from scratch

#24 hoeij

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Posted 28 August 2012 - 02:10 PM

View Postsama, on 28 August 2012 - 08:21 AM, said:

Does rechargeable batteries give you maximum performance? I was also wondering, would these new v2 ir receivers give 8043 better performance (because they get more power to the motors [ I have no clue with this technical electrical stuff])?

Under a high load, rechargeable batteries last a lot longer than regular alkaline batteries.

Alkaline batteries give a higher voltage (nominal voltage is 1.5 V per battery).  But they only produce
that voltage when (a) the load is light (say 100 mAmp) and (b) the battery is full.

But 8043 will easily draw more than 500 mAmp, and under such a load, two things happen:
(a) alkalines AA's under this load will deliver a much lower voltage than their nominal voltage
    (in fact, they'll deliver less than rechargeables)
(b) alkalines run empty much faster than the energy content written on the battery.

With rechargeable batteries, you can run the 8043 non-stop for many hours, and it'll stay
strong until the batteries are nearly empty.  With alkalines, you'll get that performance
for only a very short time, as soon as the alkalines are not completely full anymore, the
rechargeable batteries will outperform them.

So basically, you should use alkalines only for low-load applications (e.g. in the remote
control they are fine), and use rechargeables for all high-drain applications (such as: your
photo camera, your 8043, etc).

http://site.greenbat...ine-vs-nimh.jpg

In principle, the new v2 ir receivers should be better, but I suspect that the difference will
be small  (has anyone been able to notice a difference?)

#25 llenroccc

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Posted 11 December 2012 - 12:55 AM

View PostLemelisk, on 03 July 2012 - 03:47 AM, said:

In the instructions step 35 it shows a blue axle pin connecting to the yellow knob gear axle. If you replace it with a tan axle pin, the gearbox should shift much better. The surgery required for such a change may be difficult.

View PostSaberwing40k, on 03 July 2012 - 05:22 AM, said:

Yep, but if you are takin' it apart this far, try switching the 2 16z gears with one 8z and one 24z gear. For best results, the 8z gear should be on the shaft going to the motor, and the 24z gear should be on the changeover shaft. I did this with mine when I was building it, as I had read the review beforehand and anticipated the problem.
Both sound really nice solutions, I will give it a try! Thanks!




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