Page 229 - The Tribology Handbook

B14 Control cables

SELECTION OF CONTROL CABLES AND Wire can be used in push and pull conditions inside
WIRES suitable conduits (outer casings). Single strand cable
should be used inside conduits for the transmission of
The form of cables and wires which can be used for control tension loads. Rope constructions are used around pulleys.
purposes can be defined as follows: Single strand cable reinforced with a helically close wound
steel tape around the periphery of the strand provides
Wzre-a single ‘solid’ circular section 0 sufficient resistance to buckling for use within suitable
i.e. piano or music wire. conduits to transmit both push and pull loads.

Load capacity
Single strand- an assembly of wires of
appropriate shape and dimensions, Minimum breaking loads of cable taking into account the
spun helically in one or more layers helical effects of their construction are approximately 85%
around a core. of the calculated aggregate breaking load. Considerations
of safety factors to cater for possible intermittent increased
load conditions modify considerably the load capacity of
19 WIRES
cables from their minimum breaking load values to prac-
tical load values for good design. The table gives a
Multi strand-an assembly of strands recommended typical selection of single strands in relation
spun helically in one or more layers to their use within conduit.
around a core.

49 WIRES

Table 14.1 Performance of stranded cables

Minimum Overall Conduit Recommended
Overall mintmum
Strand diameter breaking Conduit diameter bend maximum
coratruction load tVpe conduit input load
mm N mm radius N
mm
I .53 2220 Single wire section 4.45 54 220

2.00 3340 Twin wire section 8.10 127 510

2.80 8000 Twin wire section 9.80 150 1780

19 WIRES 3.50 12900 Twin wire section 11.40 170 3380

5.50 28 900 Twin wire section 16.40 250 8400

36 WIRES
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Notes: Overall diameter of strand excludes thermoplastic covering. Conduits incorporate appropriate thermoplastic liners. Minimum
bend radii for conduits may well vary from the above values when the conduit construction comprises long lay wires.
B14.1