7.13: Control Cables

Question 1

What is swaging?

Answer 1

The process of applying pressure to control cable ends to have a permanent connection end fittings

Question 2

What are the most common materials in cable construction?

Answer 2

Carbon steel and stainless steel

Question 3

How can compression end fittings be swaged?

Answer 3

Kearney swager
Hydraulic/pneumatic press swager
Nicopress hand splicing tool

Question 4

What is kearney swager?

Answer 4

Cold roll forging where the metal of the terminal is subjected to a squeezing pressure applied by the kearney swaging roll dies which engages the terminal onto the cable so that the terminal cannot be separated the cable, even if the pull exceeds the breaking strength

Question 5

What sizes of cables can have a terminal or end fitting to it?

Answer 5

Any standard size cable up to 3/9 inch in diameter

Question 6

If a cable has a plastic coating, what should be done to it before swaging?

Answer 6

The plastic coating should be removed

Question 7

What should you do to eliminate longitudinal fin during swaging process?

Answer 7

Rotate the terminal 90 degrees from the first position and pass it through the rolls

Question 8

What does over-swaging cause?

Answer 8

Work hardening leading to embrittlement, so no more than four passes should be used

Question 9

What is the advantage of hydraulic/pneumatic press swaging?

Answer 9

A quicker version of traditional swaging

Question 10

What percentage and for how long are cables tested at their breaking strength?

Answer 10

60% of its breaking strength, applied gradually at least for 3 minutes

Question 11

What percentage does nicopress termination produce of a cable strength?

Answer 11

100%

Question 12

Why is a band of paint added to nicopress sleeves?

Answer 12

So if the band breaks, the cable has slipped meaning there is a fault

Question 13

How often should an inspection of control cables be done?

Answer 13

Annually or 100 hour inspections

Question 15

If a broken wite is suspected, what tool should be used for inspection?

Answer 15

A magnifying glass of 7x the power

Question 16

What are critical fatigue areas?

Answer 16

The working length of a cable where the cable runs over, under or around the pulley sleeve or through a fairlead
Any section where the cable is flexed, rubbed or worked
Any point within 12 inches of a swaged end fitting

Question 16

When does blending together of flexible and non-flexible cables happen?

Answer 16

When the outer wires are worn out by 40-50%

Question 16

What is the most common cause for kinking?

Answer 16

Improper unreeling or coiling

Question 17

Are fairleads used to change direction?

Answer 17

No those are pulleys

Question 18

What are the seals for control cables filled with?

Answer 18

Grease, to allow the cable to pass freely but also prevent pressurisation leakage

Question 19

What do pulleys have to prevent the cable from jumping out of the groove when the cable is slack?

Answer 19

A guard that is usually a clevis pin secured by a split pin

Question 20

What is necessary of newly manufactured cables before they are put into service?

Answer 20

They should be pre loaded as they increase length under load when coiled on a reel

Question 20

How should pre loads be done?

Answer 20

At a steady speed and for 5 minutes

Question 20

What cables should be preloaded over a movable guide pulley?

Answer 20

Cables over 30m long

Question 20

How are the terminals prevented from turning with the cable?

Answer 20

With special locking clips, a spring wire clips has to be inserted into the barrel hole of the terminals and the side of the left hand thread of the turnbuckle is marked by a groove

Question 21

How are turnbuckles locked?

Answer 21

Wire locking
Lock nuts
Special locking clips

Question 21

What is used to tighten cables?

Answer 21

Turnbuckle

Question 22

What is the accuracy of a tensiometer?

Answer 22

98%

Question 23

How is cable tension determined on a tensiometer?

Answer 23

By the force needed to offset the cable between two hardened steel blocks

Question 24

What is a bowden cable?

Answer 24

A type of flexible control cable used to transmit mechanical force or energy by the movement of an inner cable inside a conduit

Question 24

What are the most common diameters for control cables?

Answer 24

3/32 inch
1/8 inch
5/32 inch
3/16 inch

Question 24

What are bowden cables constructed from?

Answer 24

Stainless steel

Question 25

What are methods of push with bowden cables?

Answer 25

Two cables that give control in both directions
A cable and a return spring

Question 25

What is a double end stop?

Answer 25

Used when access is difficult to the ends of a cable so a stop is located at an accessible portion of the cable

Question 26

When connecting one to one bowden cables what is used?

Answer 26

Connecting barrel

Question 27

For multiple cables, what is used for bowden cable connection?

Answer 27

A junction box

Question 28

What are the most common bowden cable hand levers?

Answer 28

Thumb type
Ratchet type
Plain type

Question 29

What are ratchet types?

Answer 29

Allow for more than one pull on the cable allowing more cable movement

Question 30

Both the ratchet type and plain type have a throw (movement in one cycle) of how much. How much does thumb type have?

Answer 30

90 mm in radial motion. The thumb type has the same mechanism but only has 35 mm

Question 31

What are teleflex cable systems?

Answer 31

Allow for push and pull movement without the need for return cable or springs. They are stronger than bowden cables and usually have a rod or shaft inside the outer sheath for extra strength

Question 31

On single entry units, what angle does the box end unit have teleflex fittings have?

Answer 31

At least 40 degrees

Question 32

On a double entry, what is the wrap angle?

Answer 32

180 degrees