How a parking brake on small aircraft works:
There is a hydraulic line between the brake cylinders at the pedals ('toe
brakes'). The hydraulic pressure pushes pistons in the brake saddle (aircraft
fixed) against the brake disk on the wheels.
In this line there is a valve that can block this line effectively keeping the
hydraulic pressure on the brake saddle pistons although the pilot releases the
toe brakes.
This valve is usually actuated by a so-called Bowden cable. The pilot only sees
the bowden cable knob which he has to pull to close the parking brake valve. Of
course the valve needs to be kept in the closed position, so the Bowden cable
needs to be able to keep its position. To do this there are two types, both
have a typical travel of around 100mm (4inches):
1. with a knob: push the knob on the centre of the Bowden cable handle to move
the cable freely, release the knob to fix it
2. with friction: the friction is high enough to keep its position in any case,
often there is the clicking noise when moved.
So the parking brake will have two effective settings: open and closed. Any
position in between will mean the valve is partially open and therefore the
parking brake is ineffective. So apply brake pressure, pull Bowden cable out
fully and this will keep your plane from slowly rolling into an other rather
expensive object.
Cheers
Eric
> Date: Fri, 9 Mar 2012 10:57:18 +0100
> From: rob...@gmx.net
> To: flightgear-devel@lists.sourceforge.net
> Subject: Re: [Flightgear-devel] Double Input Resolution?
>
> >>> Parking brake is just a on/off flag (1bit).
> >>
> >> Well, right, but not totally. I've seen aircrafts accepting a double
> >> value, and I'd like to make it consistent. Intermediate values make
> >> sense here since it's a lever that moves along a path (or at least
> >> rotates around a hinge). It's not a two positions switch. Anyway,
> >> that's not the point, I'm just disgressing :-)
> >
> > ..I've seen levers 'n pedals used on parking brakes, if you set
> > it slowly enough, they go "click click click click", just count
> > the clicks. ;o)
>
> That's good information :-)
>
> A detail to Torsten: how does the SenecaII Parking brake "moves" along
> its path in real life? Does it click like an old car parking brake or
> does it slide smoothly?
>
> ------------------------------------------------------------------------------
> Virtualization & Cloud Management Using Capacity Planning
> Cloud computing makes use of virtualization - but cloud computing
> also focuses on allowing computing to be delivered as a service.
> http://www.accelacomm.com/jaw/sfnl/114/51521223/
> _______________________________________________
> Flightgear-devel mailing list
> Flightgear-devel@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/flightgear-devel
------------------------------------------------------------------------------
Virtualization & Cloud Management Using Capacity Planning
Cloud computing makes use of virtualization - but cloud computing
also focuses on allowing computing to be delivered as a service.
http://www.accelacomm.com/jaw/sfnl/114/51521223/
_______________________________________________
Flightgear-devel mailing list
Flightgear-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/flightgear-devel
