PullTube free instals manuals#

Due to production and design changes, aircraft companies scrap excess stock that often finds its way into homebuilder supply channels. While it is true that there are still a lot of old World War II vintage push-pull rods and tubes showing up at the Fly Markets and Country Stores, not all of the old push-pull tubes you find will be that old. each size bearing requires a separate size degreaser but they are well worth the few bucks that may be expended. Bearing regreasers cost less than most new bearings do. The gadget is secured to a bearing and the old grease is purged out by forcing new grease through the bearing under pressure from a regular grease gun. A bearing degreaser is a small inexpensive device with a built-in grease fitting. Some aircraft supply catalogs list Bearing Regreasers that can do the job. Such bearings will have to be cleaned and rejuvenated (regreased). Naturally, there is really nothing wrong with old WWII tubes except that the grease in the rods will undoubtedly have become coagulated years ago and the bearings aren't functioning or they have a lot of drag due to that ungreasy grease in them.

One problem with most any used salvage or surplus tubes you may locate is that they will probably be very old. Still, you may be able to bring home some push-pull tubes with rod ends on them that are exactly what you need except for their lengths. Outside of a lucky find at a builder-friend's shop, aircraft salvage yard, 'Country Store or Fly Market' at a major fly-in, your chances of finding used push-pull rods suitable for your need is slim. Where can you find used aircraft materials? Well, since we homebuilders tend to succumb to impulse buying and occasional scrounging, used push-pull tubes immediately come to mind. so, where do you get them? Outside of making them, that is. Unfortunately, a homebuilder cannot go to one of his local discount stores and shop around for the correct length and size push-pull tubes. On the other hand, push-pull controls are well known for their ease of movement so characteristic of friction-free push-pull systems. Additionally, the numerous pulleys and higher cable tensions generally result in a control system that may generate a need for heavy control pressures because of friction. As a consequence, the cable installation tends to become heavier and more complex than you would expect. It is well to reflect on the fact that, although individual cables are lighter than push-pull tubes, the cable systems, particularly in high wing aircraft, do require the fabrication and installation of many pulleys, brackets and guards. Anyway, one major attribute of a push-pull tube is its capability for transferring control movements through a single link (tube) positively and in direct proportion to the control input.Ī single push-pull tube can transfer either tension or compression loads (stresses) whereas a control cable system can only handle tension loads. It is also said in those ancient tomes just referenced that push-pull tubes eliminate the problem of varying cable tensions (even if the problem is no problem. Another aircraft several years its junior likewise seems to defy the need for 'frequent (or infrequent) adjustment'.Įven though cable control systems are without this alleged fault, there are some aircraft designs that are better suited to push-pull control systems. However, I happen to have a personal acquaintance with one 14 year old homebuilt aircraft that has not had its control cables adjusted in all those years. In the years to follow, one writer after another perpetuated that same spiel as gospel. I guess some expert, many years ago through logical reasoning, figured that such tension changes must take place in cables and duly recorded his conclusions as fact for posterity.

PullTube free instals manuals#

Some very authoritative books and manuals state in absolute terms that the main disadvantage of using cables for control linkages is that their tension must be adjusted frequently due to stretching and temperature changes. FIRST, LET ME set the record straight on one thing in the matter of push-pull control systems vs.