First, this was about control cable tension on an Ercoupe. Which is a
closed Loop with two free to move bellcranks and two cable with turnbuckles for
adjustments for length and tension.
OK now please tell me where your multiplier is on the system your describing.
A cable is attached to a frame = point A with a spring scale. This cable is ran
thur a pulley= point B and this pulley also has a spring scale. Now you are
returning the cable to a point that is in the approximate location of point A.
You use a turnbuckle to tighten the cable. A cable that is free to self adjust.
As you tighten the turnbuckle
tension is pulled thur both cable equally as the pulley is on a spring scale
and the point A scale will come to term with each other. Why because the pulley
will turn causing a loop pos+ to neg- reaction. The pulley is not a multiplier.
You are still using one cable.
If you are using two cable with hard points. And you set both at 175#
then you multiple by two. But the pulley or bellcrank will act as a neutralizer
until so much drag on the pivot point cause it to freeze. And then as you
tighten one cable the other will go backward in tension.
Multipliers,
Ratios. Four hard point or three would do. Tighten both cable equal. However
this is your higher math angle at which the cable attach.
As for your personal
notes. You best be happy with your life or change it. Life is to damn short.
Yes I though about
the Air Force too. Just saw enough to know it was not for me.
Being tactful is the best part of valor. Sometimes we all
forget.
-----Original
Message-----
From: Jones Family
[mailto:[EMAIL PROTECTED]
Sent: Thursday, March 22, 2001
1:34 AM
To: [EMAIL PROTECTED];
Coupers-tech
Subject: Re: [COUPERS-TECH]
Tension on cables in defence.
----[Please read http://ercoupers.com/disclaimer.htm before following any advice in this forum.]----
Warren,
After
reading your quote from Mr. Spani I can tell that we are not
talking about the same thing. The example that Mr. Spani wrote is
100% correct. Nowhere in this discussion did I say that cable
tension would be any different between the 2 cables.
If I
may use Mr. Spani's example. Lets use the same pulley system he
described but this time we will also put a spring scale on the
pulleys. The spring scale would be attached to the bolt that would
normally hold the pulley in place and then the other end of the spring scale
would be anchored to something solid. As you bring up tension on the
cables the spring scales attached to the pulleys will read twice the force
as the spring scale attached to the cables. That means that the
pulleys (not the cables) are being pulled together or toward each other at
twice the amount of force than that which is being applied to the
cables.
That is why a
cable system that is set at 175 Lb of tension will exert 350 Lb of force on
the attachment points of the pulleys. That was the only
point I was trying to make. Sorry if things got a little ugly, it would
have helped if we were talking about the same thing. You have my
apologizes.
By the way, I
have to admit that just after high school I worked as an apprentice
plumber. Sometimes I wish I would have stayed with it, I would have
probably made more money, then I could afford my own airplane instead of
renting from the Base Aero Club. Of course $65.00/Hr for a 2000 Cessna
172S isn't to bad, especially when we have 4 to chose from. And then
there is the T-34 at $72.00/Hr. On second thought, I guess I'm happy
with where I am.
Mavin Jones
-----
Original Message -----
To: Coupers-tech
Sent: Wednesday, March 21,
2001 8:43 PM
Subject:
[COUPERS-TECH] Tension on cables in defence.
----[Please read http://ercoupers.com/disclaimer.htm before following any advice in this forum.]----
Your right, I must be as low than pig dodo. I surely
cannot come up to you high standards. Wit, Master sergeant, A&P and
Intellect that you are surely know best.
So in propensity I have come to ask your forgiveness.
Because of my lack of humanity I now understand my place in this life. I make
no dejected plead. March me out and feed me to the pigs.
But in my own defense I offer this. As you undoubtedly
know for many years San Diego was the major player in Aerospace. We still have
many of the Engineers still living and working here. Being a low life plumber I
happen to have a few as customers. So I placed two calls today. If I am wrong I
wanted to see the light. One who started out as a B17 / 24 maintenance person
was out of town for the rest of the week. However Mr. Spani was home it
evening. 858-485-1052 ask for Wayne.
“ This is not a mathematical problem. This is just
common sense.” “Using one cable pull it around a pulley. The pulley will act as
the bellcrank which is free to move. Using a spring scale to act as the tie end
of the cable. When the spring scale reads x number of pounds the tensiometer
will read very close to the same. (center of span) The only difference between
the two cable is the friction drag of the bearing in the pulley or bellcrank.”
So I am guessing he is also wrong? Yours, Warren H
---------------------------------
to unsubscribe send mailto:[EMAIL PROTECTED]
____________________________________________________________
T O P I C A -- Learn More. Surf Less.
Newsletters, Tips and Discussions on Topics You Choose.
http://www.topica.com/partner/tag01
---------------------------------
to unsubscribe send mailto:[EMAIL PROTECTED]
____________________________________________________________
T O P I C A -- Learn More. Surf Less.
Newsletters, Tips and Discussions on Topics You Choose.
http://www.topica.com/partner/tag01
