Technic 42042 crane issue

[JohnsLegos]

Greetings, I am a "newbie" here so if this is not proper please let me know. I have a 42042 crawler crane and am having trouble with the motor working. The uni sits off of the floor on a shelf about 6 feet high and I don't mess with it much but the other day I took it to a Veterans Day brunch (I replaced the claw with a small US flag) and I could not get the motor to kick over. I know it is buried indite and is really inaccessible so I put in a fresh set of batteries and get a green light on the it but the motor still does not move. I also moved the clutches that operate the different functions to no avail. Also to note : the big gear box does not move at all.I contacted Lego directly to see if they have any ideas before I have to tear it apart. Any one out there have any ideas??

[Rebel_Lego]

I don't own 42042 but maybe a gear has the wrong orientation?

I think you need to take it apart anyway. Gearboxes require a lot of attention when building, speaking out of experience...

[anyUser]

The power cable is running through the inside of the crane where are also gears. It could be that the cable got damaged when it worked the last time.

(Do not worry, my version is modified: I moved the cabin to the left side)

The motor is visible when you remove the left side panel (looking from back of the crane). Its output is running to the white clutch gear at the rear.

This is accessible: Try to turn that white gear. Are the red axle joiners also truning / Do you notice considerable friction?

 

[JohnsLegos]

So basically if I pull the side panels off on the side opposite of the operators cab I should be able to see the motor right??

[anyUser]

yes - It should come off as one piece (check instruction how it got attached)

Edited November 10, 2021 by anyUser

[allanp]

When you say the motor doesn't turn, do you mean there's is nothing at all, no noise, no trying to turn at all, as if the wire is disconnected? If so, I find this usually happens when there is corrosion of the metal contacts in the plugs. It only takes a tiny amount to prevent operation.

[JohnsLegos]

Once I get a few minutes to pull the side panels apart it will give me a better idea as to what is going on. As for the motor, it seems like it is doing nothing. When I turn on the battery box none of the gears in the gearbox rotate. I know is worked before but this is confusing. And if the wire got disconnected from the motor i'd like to know how because it is down in there.

[JohnsLegos]

Ok, I took a few minutes to pull the side panels off and also was able to pull off a couple of other pieces to access the gear box. I moved the gears and everything seemed to move ok and the cable from the battery box to the motor was not stuck in anything. With it still apart I moved the switch on the battery box and it started to move the gears. Now you would usually move the switch to the far left or right but if you move it slightly back towards the off position it works so I am thinking there is something wrong with the switch in the battery box. So it is working now and if I want to show it to anyone I just have to remember to not move the switch all the way. Thanks to all that had suggestions.

[Void_S]

I guess the metallic plate under the orange plastic switch just fall apart (lost it firm connection) and now moves freeley not always following the switch position. It may be resolved if you just replace the battery box (they are in each and every PF set and cost a little) or disasseble yours and inspect the switch contacts.

[2GodBDGlory]

Yeah, it has the sliding contacts on the plastic switch that run over the circuit board. I've had some get bent out of shape before, but I'm pretty sure I got it working eventually by trying to bend them back into shape. To take a look in there, you can take off the two screws on the side, and then yank unnaturally hard down on the bottom half that holds the batteries (pushing down on the PF plug on the top may help). If you get it apart, you should be able to take a look at the underside of the switch. Like Void_S says, though it is a very cheap part to replace, with working ones on Bricklink for under $2 USD.