I just entered my third way of LEGO interest (child, 23-31, and 36+). I now have the Unimog. What a joy, I would love putting 10 of these together.

I'm noticing a problem with the pneumatics system. It is not very consistent. With one polarity it seems not to work, with the other it works mostly, but sometimes dies out. I've stripped out the "middle-men" connections and just have the pump output (bottom hole) directly connected to the crane switch bank.

At times the pump area will make two different sounds. One is a smooth sound along with the gear driving the crank going steady. This seems to produce no power. The other sound is a noisy clanking type sound and I can see the pump driving gear stopping intermittently. This give it power. There seems to be a random change between these two operations, producing the inconsistent behavior.

I will bring the whole rig into the local LEGO store in the next few days to see if they can help out, but I wanted to give you guys (the experts) a first crack at it and maybe other trouble-shooting tips.

Thanks

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Asher

did you read this topic

http://www.eurobricks.com/forum/index.php?showtopic=51101

maybe your answer is there already

I just entered my third way of LEGO interest (child, 23-31, and 36+). I now have the Unimog. What a joy, I would love putting 10 of these together.

I'm noticing a problem with the pneumatics system. It is not very consistent. With one polarity it seems not to work, with the other it works mostly, but sometimes dies out. I've stripped out the "middle-men" connections and just have the pump output (bottom hole) directly connected to the crane switch bank.

At times the pump area will make two different sounds. One is a smooth sound along with the gear driving the crank going steady. This seems to produce no power. The other sound is a noisy clanking type sound and I can see the pump driving gear stopping intermittently. This give it power. There seems to be a random change between these two operations, producing the inconsistent behavior.

I will bring the whole rig into the local LEGO store in the next few days to see if they can help out, but I wanted to give you guys (the experts) a first crack at it and maybe other trouble-shooting tips.

Thanks

--

The pump makes different sounds depending on the pressure,did u make any mistakes in the building process?

Asher

In very early releases (unlikely this is yours but just something to check) there was sometimes a problem with the small cylinder (the one that operates the grabber) leaking air. Isolate it by having it's control valve in the middle position and see if the remaining functions work consistently. You may also want to try raising the arm up as high as possible and leaving all valves in the up position (if that was the position needed to raise the arm). If the arm drops after about 30 seconds or less then it looks more likely that you have one of those earlier versons. If you still have a problem then it may be the pump that is faulty. Whatever it is, TLGs customer services are excellent and they will replace any defective parts quickly. The guys at the Lego store should be able to give you a better answer as they can see it in person.

I have exactly the same problem. I purchased two sets and one pump was consistently smooth sounding in one direction, with little power, and rough sounding in the other direction, with power. I replaced it with the pump from my second set and everything works fine.

You just need to call lego customer service to replace it.

I still managed to made use of the faulty pump in my MOC though. I used the weak stroke for dumping the bucket in my PF wheel loader with autovalve, where not a lot of power is required.

Thanks for your replies. I've found a another thread here. It may not be the issue I'm seeing but the link will be useful.

http://www.eurobricks.com/forum/index.php?showtopic=60046