Posted 05 November 2012 - 07:04 PM
After many years, a year or two ago I opened my old boxes of lego, most of them from the '80's and rebuild all my 'City' stuff including a train and also added some new stuff.
Last year I did some building in Model Team scale and now last week I presented myself with the Unimog. Still building, great fun! Never did studless building.
So now you know were I come from.
In my collection I have the forklift 8843. A while back I tried to have pneumatic parts working. They didn't.....
The cylinder rod didn't move. So I helped it a bit...... And the I had the rod in my hands, no longer attached to the cylinder. I tried to put it back in, but it came loose everytime. So (with excessive force) I opened the cylinder, re-attached the rod to the rubber thing in it, lubricated it a bit, closed the cylinder again. When I now blow in it, via a small tube (yes, please envision it) it works. Me happy.
However.... When I connected everything the right way, when I use the pump, and push, I see the rod come out a bit, but also go back once the pump goes back to its starting position. Does anybody know what part is malfunctioning?
By the way, the pump has also come loose, just like the cylinder, so I guess it is a total loss, but maybe I can fix it somehow?
Posted 06 November 2012 - 12:59 AM
The single inlet pneumatic rams also require a valve block and a switch to work properly,have you tried pushing air through these to test that they work?
Posted 06 November 2012 - 01:27 AM
It should not need any rubber bands or weight to retract if connected properly. These old single port actuators have no check valve to they are capable of extending due to positive (blowing) pressure gradient or retracting due to negative (sucking) pressure gradient. But only the valve block will allow the latter to occur. If you just connect it to a regular pump directly, it won't work. Read a bit more about it here. The 2nd generation pneumatics (which we still use) work quite differently. You can read about those here.
Sounds like you have the old pneumatics so you have to make sure you only hook them up with the valve block in the circuit.
Posted 06 November 2012 - 03:34 PM
Is there a way to test all items seperately?
Posted 26 November 2012 - 05:59 PM
Second you can hook up the pump to the cylinder. Make sure the ram of the cylinder is down before you connect. Press the pump and the cylinder should go up. Release the pump and if the spring is still working properly, the ram of the pump should go up and the one in th cylinder should go down.
Then connect the pump to the central inlet of the distribution block. When you pump the air should come out only one of the other outlets and when you release the pump (or pull it up) the air should only go in one of the inlets.You can do the same for the manual valve and move the switch to feel the air coming out or going in the inlet opposite to the side you switch the lever.
Posted 26 November 2012 - 06:46 PM
Edited by Good old Lego builder, 26 November 2012 - 06:47 PM.
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