Subject:
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Re: Old pneumatic pistons
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Newsgroups:
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lugnet.technic
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Date:
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Tue, 14 Nov 2000 23:45:43 GMT
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Viewed:
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1864 times
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One thing I found with the old-style pneumatics, particularly the excavator,
was that the down stroke was considerably easier, in fact, one had to pump
very carefully if one only wanted a minor adjustment, otherwise the pressure
of the entire liftarm would shift all of the air out very quickly.
--
Cheers ...
Geoffrey Hyde
Tobbe Arnesson <tnt@arnesson.nu> wrote in message
news:3a111746.606623258@lugnet.com...
> > As a side note: that direction valve doesn't function very good if you
> > fill up your *pneumatic* system with water (hydraulic)... case and
> > point, mine's bust due to an ill-formed stroke of genius at age 10...
>
> I broke one direction valve while playing with the 8843 Fork Lift
> Truck.
>
> To further explain how the old-style pneumatics work:
>
> The handpump creates air preassure when pressed down and suction when
> pressed up. The spring on the pump is supposed to be pressing the
> piston up but this works rather bad so one has to pull the piston by
> hand.
>
> The suction/preassure is led to the direction valve via one hoose. The
> valve looks like a grey 2x4 brick with three connections to the side
> of it. The middle connection is used to the pump and the two outer is
> connected to the valves outer connections. Then the middle connector
> of the valve is connected to the pneumatics connector.
>
> Thus will there be one "system" with preassure and one with suction
> all the way to the valve. The valve is identic to the once used today.
>
> When the valve is flipped from one side to the other both the hoose
> and the cylinder must be filled with either preassure or suction,
> hence is the "reaction" of the old system poor. Another disadvantage
> is when several valves is connected to one system using T-crosses,
> like in the 8851 Excavator the valves cannot be crossed (one valve to
> suction and one to pressure) because all the air will escape from the
> system when this is happens.
>
> One good thing is that only one hoose has to be led from the valve to
> the cylinder, but I prefer the new-style pneumatics.
>
> Hope this helps. If you want me to I can set up a page with schematics
> of the two systems.
>
> /Tobbe
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Message is in Reply To:
 | | Re: Old pneumatic pistons
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| (...) I broke one direction valve while playing with the 8843 Fork Lift Truck. To further explain how the old-style pneumatics work: The handpump creates air preassure when pressed down and suction when pressed up. The spring on the pump is supposed (...) (26 years ago, 14-Nov-00, to lugnet.technic)
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