Announcement

Collapse
No announcement yet.

Teleflex cables

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Teleflex cables

    I had a call last night from a guy asking if teleflex cables are able to be used for control systems on gyros. I wasn"t sure so I thought I would ask on here ???

  • #2
    Like this? About 400hrs on these ones now.

    Comment


    • #3
      Calidus and Cavelon gyros have teleflex cables.

      Comment


      • #4
        Yes, along those lines. Geoff asked me about the cables because he knew I used them on one of my old machines in the 90"s, I used the red jacketed stainles boat steering teleflex morse cables with 4" throw. I only used half of the throw of the cable, so the core was always well in the sheath at both ends. These cables were rated ad some huge numbers when it came to push and pull forces... one of these cables could turn a pair of 200hp outboards on a boat

        Comment


        • #5
          Can"t really answer why it was done like that, Peter Green could he built it. Probably redundancy and to make it pull pull reducing the loading dunno?

          Comment


          • #6
            Howdy guys,Teleflex cables are not mentioned in the current standards, and of course every gyro flying has a push-pull cable for the throttle. But what about for controlling the rotor head? "Teleflex" is actually a highly respected brand of flexible-sheathed push-pull cabling in marine, industrial and aviation and even aerospace. Teleflex cabling is found on most earlier jetliners for actuating systems such as smaller gear doors and things like cabin pressure outlet vents (although I don"t think for major control surfaces), and deflection of fuselage-mounted control surfaces occurs in a very small number of GA types.I am personally not aware of any certified helicopter that uses Teleflex cables for rotor control. I regard this fact as significant, given that most helicopter cyclic systems won"t tolerate any slackness in the system.In the currently being written Tech Manual I"ve included a narrative in the general reference section that ASRA prefers fully visible rigid push-pull tubes with spherical rod ends at each end. The preference is based on the fact that push-pull tubes are rigid and can readily be inspected.The major criticisms of flexible-sheathed push-pull cabling are1) There will inevitably be some slack to take up by the very nature of the design, leading to potential "deadbanding";(2) The interior condition of the sheath and cabling can"t be readily inspected; and(3) There will be inevitable friction in the system leading to higher perceived stick loads.A fairly high degree of suspicion is also attaching to flexible-sheathed push-pull cable systems as being potentially contributory in several fatal gyroplane accidents, as well as in a number of non-fatal accidents. The common concern is that the controls were not perceived to be "crisp" or "precise", that hub tilt occurred only after the (albeit usually minor) slack in the cabling was taken up; and that if the sheaths were curved significantly, that friction in the system was perceived as high. The Purnong (SA) fatal from 2010 involved cable sheaths that were curved a bit too tightly, and the internal cable was also discovered to be fraying.Ultimately, whether a builder uses Teleflex cables of rigid push-pull torque tubes is a matter of personal choice. ASRA does require that IF Teleflex or similar cabling is used, that it be brand new of the highest quality reasonably attainable, and preferably of the approved aviation type. I would expect that anyone contemplating using Teleflex cabling should firstly be aware of the problems associated with flexible-sheathed push-pull cabling.I personally am not and never will be using any such cabling.Cheers,Mark RTech Mgr

            Comment


            • #7
              Thanks Mark. The cables are a solid continuous core so there is no chance of any internal fraying and are able to push and pull enormous loads. I found it impossible to bend a cable enough to even create any drag, the minimum bend is 4" but the red jackets wouldnt allow that without huge effort (and stupidity). The only play that can occur in a teleflex cable is the inside of the sheath will eventually wear and the rod ends and there are only one at each end of each cable, making 4 rod ends in the entire control system, as opposed to an articulated 4 short rod system with 8 rod end bearings, 2 per rod. Add to that, there are even more rod ends, bushes and things in the usual exposed rod control systems, each a weak point, as is each plug in the 2 ends of each rod, that the rod end bearings are screwed into.I personally think that good quality genuine teleflex morse red jacket stainless steel cables would be more direct and less possibility of develloping any sort of play than rod systems. Getting used to my machine took a little while because it was actually so direct and light it was like driving a car with power steering for the first time. I used them on my machine because the mast was almost 2m long and almost 1m to the control stick , i would have had to go for an articulated rod system with about a dozen rod ends in the system, as well as the bell cranks etc, which would add up in weight,the complication of having room for dead straight rods between components..... each of the rod ends has a potential to add some slack to the system (or fail) each bush has the potential to wear or bind, adding even more slack..... whereas a cable is ultra smooth and direct with so little scope for problems.Another plus for the cables is that they had outrageously high load capabilities, slightly better pull than push, but still very high Will look them up) and I am sure if a pushrod system was loaded to distruction (compression), a cable would still be functioning perfectly.Cables have to be set up properly tho and they have to be the right ones. The red jackets are strongest with the largest internal diameter cable which is stainless steel and teflon lined. These cables spend years in boats pushing around pairs of huge, high horsepower outboards whilst in the worst corrosive conditions possible and suffering from years of neglect.All just my own opinion and from my experiences, that is great the big, factory machines use them, so they must be ok by ASRA. I personally think they are better all round than exposed systems. If any problems were to occur with a cable (drag/no longer smooth) which would be picked up in the daily or preflight, an entire cable could be removed and replaced with a new one in 10 minutes.I would be very interested to read about the accidents which have occured due to failing cables if you can put links to them on here, that would be appreciated. cheers

              Comment


              • #8
                if you want to test any thing test it in agriculture . the red morse cables were used extensively on a particular popular brand of tomato harvester some 20 years ago. they were a money pit and cost the owners dearly. eventually they were all changed over to 12 v electric solenoid operated hydraulics instead of the cables. "they do break."

                Comment


                • #9
                  Everything breaks on harvesters

                  Comment

                  Working...
                  X