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zsmith3rd(at)earthlink.ne
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 Posted: Fri Jul 25, 2008 6:19 pm Post subject: Cable tension |
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do not archive
In other industries, in particular those using extremely long cables....on the order of 2000 to 2500 feet, it is common practice to "stretch" these prior to actual use.
In the case of riggers building tall communications towers, a new piece of winch cable is wound onto the winch reel then unwound up a tower, over a pulley and back down, then loaded with at least 50 percent of the cable capacity to "straighten" and relax the cable. In some cases they will simple stretch the cable across a field and slowly drag a pickup truck as the cable is wound back on the winch.
Whatever method is used, they NEVER use the cable without first a good smooth pull to see that it is okay, free of burrs, defects, twists, etc.
Old crop duster (now deceased) once told me to "stretch" it before attaching second thimble.
His method was to install first thimble, then cut the cable about a foot too long.
He attached the thimble end high in the hangar and attached an old engine block to the bottom end; ran the loose end through a bolt hole, doubled it back and clamped it with Vise Grip pliers. Let it hang several days.
Idea was/is that after having been stretched, the measurement for the second thimble would be more likely to be correct for much longer......less stretch after installation.
Surely everybody has a spare 300 pound cast iron block in the back yard.
Regards to all,
Zed
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n801bh(at)netzero.com
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| Posted: Fri Jul 25, 2008 7:32 pm Post subject: Cable tension |
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It ain't the cable that worries me. It is the attach points that the cable runs on, ie, Pulleys and their brackets, fairleads, turn buckles, clevis pins. etc.....
Over and out.
do not archive
Ben Haas
N801BH
www.haaspowerair.com
-- Zed Smith <zsmith3rd(at)earthlink.net> wrote:
--> Zenith701801-List message posted by: Zed Smith <zsmith3rd(at)earthlink.net>
do not archive
In other industries, in particular those using extremely long cables....on the order of 2000 to 2500 feet, it is common practice to "stretch" these prior to actual use.
In the case of riggers building tall communications towers, a new piece of winch cable is wound onto the winch reel then unwound up a tower, over a pulley and back down, then loaded with at least 50 percent of the cable capacity to "straighten" and relax the cable. In some cases they will simple stretch the cable across a field and slowly drag a pickup truck as the cable is wound back on the winch.
Whatever method is used, they NEVER use the cable without first a good smooth pull to see that it is okay, free of burrs, defects, twists, etc.
Old crop duster (now deceased) once told me to "stretch" it before attaching second thimble.
His method was to install first thimble, then cut the cable about a foot too long.
He attached the thimble end high in the hangar and attached an old engine block to the bottom end; ran the loose end through a bolt hole, doubled it back and clamped it with Vise Grip pliers. Let it hang several days.
Idea was/is that after having been stretched, the measurement for the second thimble would be more likely to be correct for much longer......less stretch after installation.
Surely everybody has a spare 300 pound cast iron block in the back yard.
Regards to all,================================================================================================bsp; - MATRONICS WEB FORUMS -
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[url=_blank]Recharge and relax. Click for great vacation ideas.[/url]
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zodierocket(at)hsfx.ca
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| Posted: Fri Jul 25, 2008 8:22 pm Post subject: Cable tension |
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Hi Ben, I am not worried about the pully’s or attach points. The only thing I would be concerned about is the fairleads in the high tensile setting and since that is only for one circuit then I am not very concerned. The rest of the hardware can handle a lot more then you would expect. I have an 801 with a LOM engine right now that is in for repairs, it had a boo boo with the nose gear. I expect the cables were well over 200 lbs before I released as much pressure as I could, they are still well over 70 lbs but I am at the end of the turnbuckle and I do not wish to release the rudder until it is in the shop. There has been no damage to the any parts the cables are in contact with. Though this is not as big an issue with 701 and 801’s as our flapperons are tube operated and the lighter cables on the rudder and elevator are not such a big deal. The letter is directed at more of the 601 family. There have been many planes in the 601 series that I have seen with very loose cables and though in the older 601’s that cruised at 90 mph it was never really such a big deal and warranted little attention. The 601XL with a larger aileron that can cruise at 130 mph and as we have heard on the other list several guys exceeded the Vne having loose cables can be a serious issue. I believe Chris is just bringing to attention that AC43- 13B chapter 7 should be read and followed by all builders in order to have the safest plane.
Also Ben thanks for the kind words, and never be afraid to speak up against me, I write these letters late at night after a very long day. I try to help out as much as possible, but if I am in error then I expect to be slapped silly. I have no issue with admitting that I am wrong from time to time as we all are. Often I add my personal feelings into my answers as well. What I like is definitely not what everyone likes, which is the perfect reason for newbie’s to read these lists in order to get many opinions and decide for themselves. I simply tell the guys in my shop if you think your opinion is far better then mine all you have to do is convince me, if I have more reasons for my way then that is how it is done, if they have more reasons then I have, I’m open for change.
Prime example is the engine discussion for the 701, if your alternate engine is better then the Rotax, then convince me. I always had a Subaru in my 601’s until the XL. I had a Sub EA-82 MPFI Turbo mounted on the XL at first, but I was shown the light on the Corvair being a better choice so the Sub is sitting in the corner of the hanger. Yes the 701 is sporting a Rotax 912.
Mark Townsend
Can-Zac Aviation Ltd.
president(at)can-zacaviation.com (president(at)can-zacaviation.com)
www.can-zacaviation.com
--
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