This type of control system can be used in both push and pull directions and gives positive,accurate control to a remotely located device on the aircraft with only one cable. The advantage of accurate control at the receiving end by the use a sliding link or toothed wheel means that the system may be used in various positions for use with precise controls by a method of locking or restraining the lever or control device at the transmitting end by use of a system like a lever that has position locks in the form of detents (notches cut into the cotrol lever casing which the lever can lock into thus restraining it from moving until it is released from the detent/notch.
In some systems, a combination of Teleflex and conventional push/pull rods can be found to have its advantages.In this type of combination, there is Teleflex systems on either ends of the control run which are linked by push/pull rods.
There are two types of cables available.DS 23/2 OR DS 380. Both types of cable have a high tensile steel core. The DS 23/2 (also called a number two) cable has a right hand compression winding around the core which then has a left hand helix winding which is pitch spaced with a spacer winding.
The DS 380 cable has a larger diameter core wire than the DS 32/2 cable. This cable also has no compression winding. The helix winding is a right hand helix winding which is also pitch spaced by a spacer winding.
These two types of cable can be run in either a flexible conduit or a rigid conduit but Flexible conduit can have problems with excess backlash due to the clearance required between the bore of the conduit and the cable although Flexible conduit can be used in areas where the fixture may move.
Due to the backlash problem, it is necessary to keep the conduit and cable as short as possible. These cables are manufactured to be used in specific areas and the correct part number from the Illustrated Parts Catalogue must always be used.It is normal that this conduit/cable can vary in length by up to 10% and cannot be bent in a radius tighter than 9″.
Rigid conduit does not suffer from backlash to the same extent as flexible conduit and can be made from Aluminium, Light alloy, Tungum or Steel. Aluminium conduit is normally lined with PTFE (PolyTetraFluoroEthylene) to reduce friction between cable and conduit thus reducing wear and heat. Do not forget that cables expand as they heat up thus possibly moving controls. This is highly undesirable.
Teleflex control systems are normaly accompanied by various devices to aid their reliable operation including the following:-
Anti-vibration devices (Damping devices)
This is normally accomplished by a sprung loaded friction plate sprung against the gear wheel which is adjustable so that the force applied can be adjusted to ensure that the control cannot be adjusted inadvertantly by the vibration in the system.This is normally located in the transmitting device
Quick Break Unit
This is a unit that allows the rapid removal of an item in the system without altering any of the settings of the system. This saves time in fast component replacement which is very valuable in fast turn-around situations as found on the highly pressured ramp/line environments. There are many forms and designs of quick break units in use today but the basic components are:-
connecter box / casing
interlocking rods fitted to the ends of the cables
This is a ball and socket joint used where angular movement is required. The control is permitted to move only 45 degrees either side of the central position (90 degrees total). The angular travel is 8 degrees either side of the central axis giving a total movement of 16 angular degrees.
When lengths of cables are needing to be connected to complete a control system cable run, connectors are required.They sometimes are equiped with nipples for lubrication and can be fixed to the structure. It is worth noting that the type of connector used with the PTFE type of conduit has a larger internal bore than a standard connector.With all this in mind the necessity to check the IPC for the part number is obvious.
Sliding end Fittings
These units are used where it is not necessary to convert lateral motion into any other form of motion. This is operated by the pushing and pulling of the cable by a handle located on the transmittting end of the conduit and secured by a split collet or lock spring and plug assembly. Like many other cable connections a witness hole is provided to ensure safe engagement.