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Poles have forces exerted on them from different sources.
Wind, snow, ice and weight on one side are just some of the issues.
In this case we are looking at sideways forces, which can occur
on pole routes situated on bends (pull
on pole) or when there is more wiring provision on one
side of the pole.
There are two ways to resolve the above issues. Struts can be
installed, which are wooden poles that brace the pole against movement and wires
stays that hold a pole in position.
STRUTS
P.O. ENGINEERING DEPT.
ENGINEERING INSTRUCTIONS
LINES
OVERHEAD
D3126
Issue 1, 11.2.38
STAYING
Fitting and Use of Struts
1. General
Where the direction of the angle in a pole-line is such that local conditions
preclude the fitting of a stay, the stress imposed upon the pole by the tension
of the line-wires should be taken up by a strut fitted to the pole on the inside
of the angle, as detailed in this Instruction. Struts should also be used as
substitutes for transverse stays where provision of the latter is impracticable,
see D 3001.
2. Principles of construction
The following principles should be borne in mind when fixing struts:-
-
The structure should be built up so as to be capable of resisting
stresses in either direction upon the line, such as those induced by cross
winds; in effect, the strut should be capable of acting also as a stay.
This condition is obtained by fitting a block near the butt end of the strut
and of the pole, and by adding a tie-bolt to make the structure rigid.
-
The ideal position for the attachment of a strut to a pole is at the
point at which the resultant stress, due to the wires, acts upon the pole.
Attachment in this position is generally undesirable, however, since it
would necessitate the employment of arms of increasing length below the
resultant point, to carry the wires clear of the strut. Struts should
therefore be fixed below the position of the lowest arm which may be
ultimately required. This constitutes the weakness of this type of
construction, as, under the action of heavy stresses, the pole tends to
break at the point of attachment of the strut. For this reason, poles which
are to be fitted with struts should, on stout pole-lines, be the stoutest
available, and, on other lines, one class heavier than those used in
straight sections of the line, see C3001.
-
A strut should be fitted in such a manner that the pole is not weakened; incisions or mortices should not be made in the pole for the purpose of
fixing the strut.
-
A strut should be arranged so as to make a reasonably wide angle with
the pole which it supports, since its efficiency depends on the same
principle as that which determines the efficiency of stays.
Where it is necessary to fit struts to a number of consecutive poles, a
uniform angle should be adopted, since a succession of struts forming
widely-varying angles looks very unsightly.
3. Details of construction
Strutted poles should be built up as shown in Fig. 1. Details are as follows:-
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Type of pole to be used. Sound "seconds" poles may be used for struts ;
any arm slots should be filled in neatly with "Strip, Creosote" and the
strut should be fixed with the arm slots on the under side. Struts of
"seconds" timber should be coated with "Creosote and tar" after erection. If
"seconds" poles are not available, new poles, somewhat lighter than those
used for the pole-line, should be employed.
-
The head of the strut should be brought to a feather edge and scarfed to
fit the pole, so as to make a sound water-tight joint; the surfaces which
are brought into contact should be coated with "Creosote and Tar". The head
of the strut should be fixed to the pole by means of a arm-bolt
passing through the bottom of the scarfed portion.
-
A tie-bolt should be fixed between the pole and the strut, about midway
between the head of the strut and the ground line. Where strutted poles are
in such a position that a horseman can ride between the strut and the pole,
the tie-bolts should be at least 12 ft. above the ground; where the opening
is narrow, cattle guards should be fixed as described in C3251.
-
Taper washers should be provided, to ensure a satisfactory seating on
the strut for the arm-bolt at the top, and for the nut and tube of the
tie-bolt. These washers are of two kinds, circular and square, known
respectively as "Washers, Galvanised, Nos. 14 and 15" ; the latter has one face
hollowed out to fit the curved surface of a pole. Three "Washers Galvd., No.
15" are required for each strut, and sufficient "Washers, Galvd., No. 14"
should be used to provide seatings approximately at right-angles to the axis
of the bolts.
-
At the pole, two "Washers, Galvd., No. 6" should be fitted to the
tie-bolt, as shown in Fig. 1.
-
Blocking the foot of the pole and strut. Slots should be cut near the
bottom of both the pole and the strut, and medium or heavy stayblocks,
depending on the class of pole and the character of the soil, should be
bolted securely to each, using R-in. arm-bolts and "Washers, Galvd., No. 8."
"Seconds" timber should not be used for these blocks. The foot of the strut
should be at least 4ft. in the ground.
FIG. 1
STRUTTED POLE
P.O. ENGINEERING DEPT.
ENGINEERING INSTRUCTIONS
LINES
OVERHEAD
D3126
Issue 3, 3.7.1970
STAYING
Fitting and Use of Struts
1. General. A strut should be fitted to strengthen a route only in cases
where local conditions make it impracticable to fit a stay. The strut shall be
fitted to the pole on the inside of the angle.
2 Principles of construction
The following principles should be borne in mind when fixing struts:-
-
The structure should be built up so as to be capable of resisting
stresses in either direction upon the line, such as those induced by cross
winds; in effect, the strut should be capable of acting also as a stay. This
condition is obtained by fitting a block near the butt end of the strut and
of the pole, and by adding a tie-bolt to make the structure rigid.
-
The ideal position for the attachment of a strut to a pole is at the
point at which the resultant stress due to the wires acts upon the pole.
Attachment in this position is generally impractical, however, since it
would not be possible to attach the aerial cable fitting on the strut.
Struts should therefore be fixed below the aerial cable bracket or the
position of the lowest arm which may be ultimately required. This
constitutes the weakness of this type of construction, as, under the action
of heavy stresses, the pole tends to break at the point of attachment of the
strut. For this reason, poles which are to be fitted with struts should, on
medium pole routes, be specially selected from the poles available, i.e. be
those with the greatest diameters, whilst on light pole routes medium poles
should be used.
-
A strut should be fitted in such a manner that the pole is not weakened;
incisions or mortices should not be made in the pole for the purpose of
fixing the strut.
-
A strut should be arranged so as to make a reasonably wide angle with
the pole which it supports, since its efficiency depends on the same
principle as that which determines the efficiency of stays (see D1151 and D3026).
Where it is necessary to fit struts to a number of consecutive poles, a
uniform angle should be adopted, since a succession of struts forming widely
varying angles looks very unsightly.
FIG. 1. STRUTTED POLE
3. Details of Construction
A strutted pole is shown in fig. 1.
-
Type of pole to be used for the strut. Sound recovered poles less than
fifteen years old, or new poles somewhat lighter than those used for the
pole line, should be used for struts. When a pre-cut pole is used the
pre-cut surface should be on the under side.
-
Blocking the foot of the pole and strut. Slots should be cut near the
bottom of both the pole and the strut and medium or heavy stay blocks,
depending on the class of pole and the character of the soil, should be
bolted securely to each,
using 5/8in. arm-bolts and Washers, Galvanized, No. 8 (see Fig. 1). The
foot of the strut should be at least 4ft. in the ground.
-
The length of the strut, and the angle which it makes with the pole can
be determined using a piece of sash line held taut between the proposed
point of attachment of the strut and the ground.
-
The strut should be cut to the required length, i.e. the distance
measured with the sash line plus the depth of the strut hole.
-
The head of the strut should be brought to a feather edge and scarfed to
fit the pole so as to make a sound water-tight joint; the surfaces which are
brought into contact should be coated with Creosote and Tar.
-
The strut hole should be excavated and the strut lifted into position by
one of the following methods (g and h).
-
If mechanical aids are available, i.e. Pole Erection Unit, crane etc.
These should be used as considerable savings in manpower may be achieved.
-
If there is sufficient room the strut should be placed as shown in Fig.
2 and the following method of erection used (i to l).
-
Lash a single block to the pole just above arm bolt hole and pass a long
arm bolt through arm hole to prevent any rope slip when under tension.
-
With the lifting rope attached to the strut by means of a timber hitch
halfway between the point of balance and the top of the pole lift the strut
as shown in Fig. 2.
-
When the strut is near its final position the lifting rope should be
held taut and final positioning achieved by the use of pole lifters, i.e.
one on either side to hold it securely whilst the hole is drilled.
-
Do not attempt to lift the strut through the vertical position.
-
If there is insufficient room to place the strut as outlined in (h) the
strut should be placed as shown in Fig. 3 and lifted into position and
secured as previously described.
-
The head of the strut should be drilled horizontally with an Augers,
Screw 7/8in. so that the hole passes through the bottom of the scarfed
portion. The head of the strut should then be secured by means of a a 5/8in.
arm-bolt passed through the drilled hole and the pole. The pole lifters and
lifting rope may be removed when the arm bolt is fitted and secured.
-
Similarly a tie-bolt should be fixed between the pole and the strut
about midway between the head of the strut and the ground line. Where
strutted poles are in such a position that a horseman can ride between the
strut and the pole, the tie-bolts should be at least 12ft. above the ground.
Where the opening is narrow a cattle guard should be fitted as described in
para. 4 and the tie-bolt fitted to the pole through the cattle guard and
strut as shown in Fig. 4.
-
Taper washers should be used to ensure a satisfactory seating on the
strut for the arm-bolt at the top and for the nut and tube of the tie-bolt.
These washers are of two kinds, circular and square, i.e. Washers,
Galvanized, No. 14 and 15 respectively; the latter has one face hollowed out
to fit the curved surface of a pole. Three Washers, Galvanized, No. 15 are
required for each strut, and sufficient Washers, Galvanized, No. 14 should
be used to provide seatings approximately at right-angles to the axis of the
bolts.
-
At the pole, two Washers, Galvanized, No. 8 should be fitted to the
tie-bolt, as shown in Fig. 1.
FIG. 2
FIG. 3
Cattle guards
Where it is possible to provide only a small spread for the strut such that the
distance between the pole and strut is insufficient for cattle to pass through
easily, and there is a danger that they may become jammed, a vertical guard
should be provided (see Fig. 4). The guard should consist of a 6-8ft. length of
sound recovered pole timber shaped to a diamond point at one end and bored with
a i in. hole as shown in Fig. 4. All cut surfaces should be thoroughly treated
with creosote and tar before fitting. The guard should be buried in the ground
to a depth of 18-24ins. midway between the strut and the pole and secured by a
tie-bolt of suitable length. Two lengths of Tube, Galvanized, one each side of
the guard, should be fitted on the tie-bar to act as spacers. A Washer No. 8
should be fitted on the tie-bolt on each side of the guard and pole respectively
and Washers Nos. 14 and 15 on each side of the strut as described in para. 3 and
illustrated in Fig. 4.
FIG. 4
STRUTTED POLE WITH CATTLE GUARD
STAYS
P.O. ENGINEERING DEPT.
ENGINEERING INSTRUCTIONS
LINES
OVERHEAD
D3051
Issue 2, 21.7.61
STAYING
Staying Materials and Fitting of Stays
1. Scope of Instruction
This Instruction describes standard staying materials and fittings and their
uses, and indicates the methods to be used in staying aerial lines. The fitting
of stays on light rural lines where the ultimate development is small is, in the
main, identical with that described herein; certain exceptions are made,
however, and these are detailed in H3001. Information relating to the provision
and use of individual types of stay will be found in D3001. The methods of
determining the size and number of stays required are described in D3026.
2. Materials
Generally, stays on poles consist of standard galvanized mild-steel wire
attached to a rod fitted with a tightening device and secured to a buried block.
In the case of light rural lines, however, lighter stay-wires are also used (see
H3001). Details of the various materials and fittings used for staying are
given in Table 1. Typical stay-rods, swivels and tighteners are illustrated in
Figs. 1, 3 and 4.
3. Stay-rods
The upper end of Rods, Stay, Nos. 1 and 2 (see Fig. 1) is provided with 12in. of
screw thread for adjustment of the stay, and is fitted with a bow and thimble
for attachment of the stay-wire. To prevent interference with the adjustment of
the stay by unauthorized persons, a locking rack-nut is used to secure the bow
to the rod. The lower end of the stay-rod terminates in a stout, square
bolt-head ; a large square washer, having a square central hole fitting the neck
of the rod, abuts against the head. A circular hole is provided in one corner of
the washer, through which a nail is driven into the stayblock, to prevent the
stay-rod turning when the
stay is being adjusted. Rods, Stay, No. 5, for light rural lines, are of similar
design except that only 9in. of screw thread is provided for adjustment of the
stay. Rods, nuts, washers and thimbles for Rods, Stay, Nos. 1, 2 and 5 are
available as separate items to save wastage of re-usable stay-rod parts. Each
part, together with its proper description, is indicated in Fig. 1. It is
important that when stays are recovered, those components of the recovered
stay-rod which are in good condition should be held locally for re-use when made
up into complete stay-rods.
FIG. 1
RODS, STAY NO. 1, 2 & 5
4. Stayblocks
Stayblocks should be cut locally from sound recovered pole timber. The blocks
should be cut to the size, or one of the alternative sizes, shown in Table 1. If
due to the size of recovered timber available a rectangular block cannot be cut,
the edges of the block may be chamfered or waned on one side as shown in Fig. 2. Each block should have a hole
drilled centrally in the face to take a stay-rod of the size indicated in Table
1. The blocks should be liberally treated with Creosote and Tar and stacked in
open formation to allow free circulation of air; when taken from stock they
should be examined to ensure that they are free from decay. The conditions of
use of extra light, light, medium and heavy stayblocks in conjunction with the
various sizes of stay-rod in average soils are given in Table 1.
FIG. 2
STAYBLOCK
TABLE 1
MATERIALS AND FITTINGS USED FOR STAYING
5. Stay-swivels, Fig. 3, consist of a turnbuckle with a screwed eye-bolt at
one end and a swivel-eye at the other. They are provided for the adjustment of
all stays not incorporating a stay-rod, in positions where the tightening
device, fitted near the point of anchorage, is not liable to interference.
FIG. 3
SWIVEL, STAY 5/8in.
6. Tighteners 5/8in. (see Fig. 4)
These have a short, screwed eye-bolt in place of a rod, but are in other
respects identical with the No. 1 stay-rod. They have a self-locking rack-nut,
and should be used in place of stay-swivels where the stay adjustment is
accessible to unauthorized persons.
FIG. 4
TIGHTENER, 5/8in.
7. Anchorage of stay
To ensure the full efficiency of a stay it is essential that the stayblock and
stay-rod, or other device for anchoring, should be fixed so firmly and rigidly
that it will remain unyielding under a stress equivalent to the breaking load of
the stay-wire. Stays should be anchored in the ground, wherever possible. Only
in exceptional circumstances should a stay be attached to a wall or other
structure.
8. In fixing a stay, full advantage should be taken of the facilities
afforded by the site. The point of anchorage should be as far from the pole as
possible, subject to the limitations of A0011, D3001 and D3026. It should be
carefully determined so that:-
-
the stay will be in the correct position relative to the direction of the
line, and
-
where the stay has to pass through a bed of line-wires, adequate clearance
from all the wires will be provided, avoiding the use of a stay-crutch wherever
possible.
The direction of an angle stay or a transverse stay, relative to that of the
line, should be determined as described in C3021 or D3026. If the pole is
already in position with the arms correctly aligned, the direction of the stay
will be parallel to that of the
arms and may be obtained by sighting along them. A length of light (No. 2) sash
line secured to the pole at the point of attachment of the stay, and pulled taut
near the proposed point of anchorage, will indicate the position providing the
best clearance from the line-wires.
9. Assembly of stay-rod and stayblock
When the stayblock used has chamfered edges (see Fig. 2), the stay-rod should be
inserted from that side of the stayblock which will ensure that the greater flat
(bearing) surface is uppermost. The stay-rod washer should be nailed to the
block, using a Nail, Rose-head, 3in.; alternatively, a Screw, Coach may be used.
10. Excavation for stayblock
The stayblock should be buried to a depth varying from 4ft. to 6½ft.
according to the character of the soil, but as, in normal situations, all but a
few inches of the unscrewed portion of the rod should be buried, the depth will
generally be determined by the angle of the stay. The angle of the stay should
also be taken into consideration in determining the distance from the position
of the stay at the ground line to the hole for the stayblock (see Fig. 5). The
hole should be under-cut in the manner shown in Fig. 5, so that the stayblock
may be at right-angles to the direction of the stay and bear against solid,
undisturbed earth, and thus provide the maximum resistance to the upward pull. A
groove, as narrow as possible, should be cut from the ground surface to the
undercut portion of the hole, to take the stay-rod and permit of its alignment.
Generally, for cutting the groove, a pick is most suitable near the surface and
a crowbar or a digging bar for the deeper portion. When using the pick, cut from
the hole towards the shallow end of the groove, and so avoid displacing soil
unnecessarily from the side of the hole.
FIG. 5
EXCAVATION FOR STAYBLOCK
11. Anchorage in rock
Where rock of suitable hardness and formation for direct attachment of the stay
exists at the point of anchorage, a hole should be drilled in the rock and a
ragged eye-bolt, obtained locally, cemented in (see Fig. 6). Where the rock is
at the ground line and a 5/8in. diameter rod will provide the strength required,
a Tightener, 5/8in. should be used, as shown in the illustration, with the eye
of the eye-bolt inter-linked with that of the tightener. In other circumstances,
a stay-rod of appropriate size should be used in conjunction with the eye-bolt.
The bolt-head should be removed from the rod, and the end forged into an eye,
linked to the eye-bolt.
FIG. 6
ANCHORAGE IN ROCK
12. The eye-bolt should be made from rod of approximately 1/8in. greater
diameter than the stay-rod (see A, Fig. 6). It should be forged with a long weld
and suitably increased in diameter at the neck (B, Fig. 6). As all but the eye
should be buried in the rock, the length of the bolt (see C in Fig. 6) should be
equal to the depth of setting required. The length of the bolt and the depth and
angle of setting must depend, among other things, on the class of rock (i.e.
hard or soft), the relative position of the rock, and the angle between the face
of the rock and the stay. Generally, the depth of setting should be 1 ft. in
hard rock, and 18 in. or over where the rock formation is in layers or has a
tendency to split or crumble near the surface. The eye-bolt should generally be
set at right-angles to the stay, but the angle between the bolt and the face of
the rock (see D in Fig. 6) should never be less than 45° in hard rock, or 60°
where the fixing is in rock of other classes. To prevent corrosion, the
eye-bolt, together with the bolt of the tightener or stay-rod (from which some
of the galvanized coating will have been removed by the forging operations),
should be galvanized, if possible, or painted with two coats of Paint, Black,
for Ironwork, the first coat to be quite dry before the second is applied. The
screw thread should be covered with Tallow, Tar and Pitch Composition (see par.
35)
13. Attachment to walls
Stays may be anchored to the brick, stone or concrete walls of buildings,
bridges or other structures only when no other anchorage is available and the
structure is manifestly capable of sustaining the load. The point of attachment
should be at such a distance from the top or other edge of the wall as will
ensure that the maximum load on the stay can be supported without risk of damage
to the structure. The method to be used in attaching the stay depends upon the
load, the angle between the stay and the face of the wall, and the nature and
condition of the structure.
14. For lightly-loaded stays where the angle between the stay and the face of
the wall does not exceed 60°, Spikes, Eye, 6in. (or 9in.) afford the simplest
means of attachment and should generally be used. To ensure a firm fixture, all
but the eye of the spike should be fixed in the well, a hole approximately 1in.
in diameter being cut to the necessary depth. The eye-spike should be cemented
in, or driven into a plug of creosoted pine inserted in the hole; the latter
method of fixing permits attachment of the stay without delay. Plates, Wall No.
4, secured by means of Spikes, Galvanised 7in. provide an alternative means of
attachment. In fixing the plates, the wall should be plugged, the plugs being
made and fixed as detailed in E3134.
15. For heavy loads, or where the direction of the stay is approximately
perpendicular to the face of the wall, the stay should be anchored by means of a
forged eye-bolt and nut, passing through the wall. Two Plates, Wall, No. 2 (see
Table 1) should be fitted to the bolt to provide a satisfactory bearing surface
on each side of the wall. The eye-bolt, made of rod 3/4in. to 1in, diameter,
depending on the size of the stay required, should be obtained locally. It
should be galvanized, if possible, or painted with two coats of Paint, Black,
for Ironwork, and the screw threads coated with Tallow, Tar and Pitch
Composition (see par. 35).
16. Generally, the eye of the eye-spike, wall-plate No. 4, or eye-bolt
referred to in pars. 14 and 15, should be connected to the swivel or tightener
(see pars. 5 and 6) by means of a short length of stay-wire, a Thimble No. 2
being used to protect the wire at the eye. A thimble is supplied with each
Plate, Wall, No. 4, but has to be requisitioned separately for an eye-spike or
bolt.
17. Alignment of stay-rod and preparation of rod for attachment of wire
Stay-rods should be aligned so as to form, with the stay-wire, a straight line
from the stayblock to the point of attachment to the pole (see Fig. 5). The
stay-rod must not be bent to bring the stay-rod into alignment with the stay.
When correct alignment has been obtained, the hole may be filled in. The nut and
bow should be removed from the stay-rod, their bearing surfaces smeared with
Tallow, Tar and Pitch Composition (see par. 35), and about 5 in. of the screw
thread at the end of the rod coated with the mixture. The bow should then be
replaced, and the nut screwed on a few turns only. The stay-rod is then ready
for the attachment of the stay-wire.
18. Fitting of stay-wire
Stay-wires are attached by looping the end of the wire round the pole or thimble
and then making-off upon the standing part of the wire. (Clamps, Stay, are
provided for use only in conjunction with Wire, Suspension, principally used for
aerial cable suspension, and should not be used in the attachment of other types
of wire.)
19. Tools
Tools, Splicing, Large (or Small) - illustrated in Fig. 7 - should be used when
making-off all stay-wire (except 7/14 wire, which can easily be made-off by
hand). Two hooks are provided, one at each side of the tool, so that the wire
may be made-off in either a right-hand or left-hand direction, according to the lay
of the strand. (A left-hand lay is now standard.) Use of the large tool will
facilitate the operation, and is therefore preferable where sufficient space is
available. Use of the small tool should generally be confined to places where
obstructions preclude the use of the large tool, e.g. between line-wires.
FIG. 7
STAY-SPLICING TOOLS
20. Cutters, Bolt, No. 2 should be used to cut stranded stay-wire to the
length required.
21. Attachment to pole
Instructions concerning the position of the stay on the pole in relation to
adjacent arms and line-wires are given in D 3001. Stay-wires should, generally,
be attached to poles before erection. This procedure should also be followed on
existing lines when a stayed pole is to be replaced or added, if the stay-wire(s)
will not interfere with the erection of the pole and transference of the wires.
22. When fitting stays to existing poles, care should be exercised to avoid
contact between the stay and the line-wires. The small splicing tool should
generally be used. That portion of the stay-wire which is likely to foul the
line-wires may be insulated from them by enclosing it temporarily in a length of
rubber hose; hose of 1/2in. internal diameter is generally suitable. One side of
the hose is cut through longitudinally, the stay-wire inserted through the cut,
and the hose bound with string to secure it in place.
23. It is advisable to make-off the wire of an angle or transverse stay at
the back of the pole, i.e. opposite to the side on which the arms are fitted,
and parallel with the line-wires. In this position the small splicing tool can
generally be rotated without difficulty. When the make-off is completed, the
stay-wire should be turned to its correct position, and secured by means of
staples, as described in par. 30.
24. That portion of the stay-wire which is lapped round the pole should not
be unstranded.
25. Number of laps round pole
Where only one stay is being fitted at one point on a pole, the wire should be
lapped twice round the pole, the second turn crossing the first on the side
opposite to the make-off. Where two stays are being attached at the same point
but on opposite sides of the pole, only one turn of each stay-wire round the
pole is required, but one stay-wire should be crossed over the other.
26. Forming knees, and length of wire for attachment to pole
When the wire has been passed round the pole, it should be secured by means of
two Staples, Galvd., 2½in. and then bent to form two knees, as illustrated by A
and B in Fig. 8. The free end will then lie closely alongside the standing part,
and the wire can be made-off close to the pole, thus avoiding any tendency to
slip under load. The length of wire required for the free end, Y in Fig. 8,
depends upon the size of the stay-wire; appropriate lengths are given in Table
2. The length of wire round the pole should be sufficient to ensure that, when
the stay is tight, the lower loop (A-C-B in Fig. 8) is approximately in
alignment with the rest of the stay, clearance from arms, etc., being taken into
consideration (see also Fig. 10).
FIG. 8
27. Making-off
Stay-wire should be made-off in the following manner:-
Unstrand the free end, and straighten out the individual wires. Select, for the
first lapping, the wire which crosses the others at the knee on the side remote
from the main wire, bend it outwards at the knee and arrange the remaining
wires symmetrically alongside the main wire, as illustrated in Fig. 8, so that
the completed make-off may be as neat and compact as possible. (When stay-wire
is being made-off to a thimble and the splicing tool is used to draw the wire
into the groove of the thimble and hold the knees together (see par. 34), keep
the tool in position during the foregoing operations. Release the grip only to
take out the wire for the first lapping.)
28. Next, with the splicing
tool in position - the hooks pointing in the direction of the lay of the strand
(see Fig. 9),engage the free wire with the hook on the pole side of the tool.
Bend the wire back over the hook and, keeping it in this position, revolve the
tool in the same direction as the lay of the strand, thus binding the wire
closely and tightly round the main wire and the remaining strands. Make eight
laps with this wire, bend the end towards the pole and out of the way of the
tool, and leave it to be shortened and pressed into the make-off later. Then
select and bend up a wire for the second lapping and, engaging it with
the same hook of the tool, turn as for the first wire. Deal with each succeeding
wire in a similar way, making the appropriate number of turns specified in Table
2. The use of pliers for this operation would damage the galvanizing and is
therefore prohibited.
TABLE 2
MAKING-OFF STAY-WIRES
FIG. 9
MAKING-OFF
SPLICING TOOLS IN OPERATION
29. The portion of each wire remaining, after the requisite number of laps
have been made, should be shortened sufficiently to permit the end being worked
into the make-off ; the length should be such that one lapping finishes at the
beginning of the next. This is done by nicking each wire, by means of pliers, at
the point where the lapping will finish (Fig. 9) and, after it has been pulled
into the make-off by means of the splicing tool (used as described in par. 28),
breaking the wire off by bending it from side to side. The splicing tool should
then be placed over the make-off so as to embrace the end of the first of the
shortened wires and, by revolving the tool in the same direction as the lapping,
the end should be pressed into position. This procedure should be repeated for
each of the ends in turn. A finished make-off is illustrated in Fig. 10.
30. Stapling to pole
When the make-off has been completed, the two staples at the knees (Figs. 8 and
9) should be removed and, before the stay is tightened, the stay-wire should be
finally stapled to the pole, as follows:-
-
When the stay-wire is lapped twice round the pole (see par. 25) one
Staple, Galvd., 2in. should be used at the point where the two turns cross (see
Fig. 10).
-
When the stay-wire is only taken once around the pole, the stay should be
stapled only on that side which is remote from the make-off.
31. Length of Stay-wire
-
full engagement of the nut of the stay-rod stay-swivel or tightener is
obtained without deflecting the pole from the vertical more than is
necessary to allow for settlement and
-
the maximum length of screw thread is available for subsequent
adjustment. This should be determined before beginning the second make-off
by IN POSITION carefully tightening the wire or, in the case of an overhead
stay-wire to be made-off on the ground, by measurement.
32. A Vice, Draw, No. 2 should be used to tighten the wire. It should be
connected to the stay-rod or corresponding holdfast by means of a length of
Wire, Stay, 1/8 or a Tail Insulated, Large. The vice jaws should grip the whole
stay-wire. Attachment to a single strand is not permitted; such practice would
damage the strand and its galvanizing and destroy the symmetrical formation of
the stay-wire.
FIG. 10
MAKE-OFF ON POLE FINISHED AND STAPLED IN POSITION
FIG. 11
ATTACHMENT OF STAY-WIRE TO THIMBLE FORMING KNEES
33. Attachment to thimble
The stay-wire should be bent to form two knees at the point where it is to be
made-off to the thimble (see A and B in Fig. 11). The distance between the knees
(see X in Fig. 11) is dependent upon the size of the wire and thimble.
34. The length of wire required for the make-off (Y in Fig. 11) depends upon
the size of the stay-wire; appropriate lengths, for each size of wire, are given
in Table 2. The wire between the two knees should be bent to fit closely into
the groove of the thimble.
The splicing tool may be used to draw the knees together as shown in Fig. 12,
thus bringing the free end alongside the main wire. The wire should then be
made-off as detailed in pars. 27 to 29. Making-off will be made easier by the
removal of the vice and tail referred to in par. 32. These may generally be
dispensed with when the first turn or so of the make-off has been made, but,
where the tension to be maintained is such that removal of the vice at this
stage would result in slipping, one of the individual wires of the free end (the
central wire in the case of 7-strand wire) should be connected to a second
draw-vice, which should be attached to the main wire as described in par. 32
before the first is removed. Examples of the finished make-off of various sizes
of stay-wire are illustrated in Fig. 13.
35. Adjustment of stay and protection from corrosion
When the stay-wire has been made-off at both ends, the threaded portion of the
stay-rod or eye-bolt below the nut or swivel should be given a thick coating of
Tallow, Tar and Pitch Composition. This mixture consists of 40 parts of tallow,
40 parts of coal tar and 20 parts of mineral pitch, and provides an effective
protection against corrosion. The stay should then be tightened as required and,
finally, any thread above the nut recoated with the mixture. The coating should
be continuous and should be maintained in this condition, any thread exposed as
a result of subsequent adjustment being re-coated when the adjustment is made.
In areas where corrosion is likely to be accelerated by fumes, salt-spray, etc.,
each make-off should be completely coated with Paint, Black, for Ironwork.
36. Stayguards are used to protect stays and render them readily visible, and
thus avoid risk of damage and of injury to persons or animals. All stays
anchored beside footways, on road margins or grazing land, or in other places
where collision with the stay could occur, should, therefore, be fitted with
stayguards. Stays fixed on pasture or arable land which is likely to be used for
grazing at any time should be similarly guarded. Stayguards should be prepared
locally from sound recovered pole timber to approximately the dimensions shown
in Fig. 14. After preparation the stayguards should be treated with Creosote and
Tar.
FIG. 14
STAYGUARD AND METHOD OF FIXING
37. Fixing
The position of the guard on the stay, and the length above ground, should be
determined with due regard to the position of the anchorage. In normal
situations, the stayguard should stand 6 ft. out of the ground and be fixed on
the upper side of the stay. The stay-rod and wire should be stapled to the guard
by means of Staples, Galvanised, 21 in. In addition, a wrapping of Wire, Stay 1/8
(or of similar wire from the surplus ends of stay-wire), fastened to the
stayguard by means of Staples, Galvanised, l in., should be applied to make the
attachment secure. Staples should be fixed clear of the make-off and screw
thread, to ensure free movement of the stay-wire and nut when the stay is
subsequently adjusted. Details are illustrated in Fig. 14.
38. Overhead (or gallows) stays
The direction of an overhead terminal, angle or transverse stay relative to that
of the line-wires should be as specified in D 3001. The gallows pole should be
set in a direct line with the pole to be stayed (the 'line' pole) and the point
of anchorage of the ground stay, so that all parts of the stay, i.e. the
overhead stay-wire, the gallows pole and the ground stay, are fixed in the same
vertical plane. Where two or more ground stays are required, however, they may
be arranged as shown in D 3026, Figs. 10 and 11, and thus provide additional
support for the gallows pole against side stresses. It is advisable that the
gallows pole should have a slight initial set, in the direction of the stay,
towards the ground stay. Among trees, however, or where the gallows pole is
otherwise inconspicuous, the inclination towards the ground stay may be
increased with advantage. In setting the gallows pole, a firm footing should be
provided to counteract any tendency to sink deeper into the ground. Where
unstable ground is encountered the pole should be blocked, the stayblock being
fitted at right-angles to the direction of the stay and at the butt end of the
pole on the side remote from the ground stay. The hole for the gallows pole
should be dug in the direction of the stay.
39. To ensure that adequate provision is made for future adjustment, a
Swivel, Stay, 5/8in. should be provided for the overhead stay-wire and the stay
fitted as follows:-
-
Erect the gallows pole (see par. 38).
-
Fix the ground stay, attaching it to the gallows pole at a distance from
the top equal to the diameter of the pole. Attach the stay so that the two
turns of wire round the pole pass through the eye of the swivel eye-bolt and
secure the bolt at 180° to the make-off (see Fig. 15). If a second stay is
required, fix it in the position indicated in Fig. 15.
-
Make-off the overhead stay-wire on the line pole, as detailed in pars.
18 to 30. The wire should generally be attached immediately above an arm. In
this position, the best possible clearance is provided between stay-wires
approaching the horizontal and the line-wires.
-
Screw the swivel turnbuckle on the eye-bolts, engaging a few threads
only.
-
Complete the fitting of the overhead stay-wire by one of the following
methods:-
i) Where the wire can be made-off on the ground. Measure, by means of a
measuring tape or length of sash-line, the exact length of wire required
between the line pole and the swivel. Take off the turnbuckle and, using the
measurement, attach the stay-wire to the thimble (see pars. 33 and 34).
Raise the wire, and tighten it by means of a draw-vice connected to the
gallows pole. Screw the swivel turnbuckle on the eye-bolt.
ii) Where it is necessary to make-off the wire in its final position.
Tighten the wire by means of a draw-vice connected to the gallows pole, and
make-off to the swivel as detailed in pars. 33 and 34.
-
Re-adjust the ground stay, if necessary.
-
Adjust the swivel so that the line pole is vertical.
-
Coat all screw threads (see par. 35).
40. Stay-crutches
When the choice of the position for the stay anchorage is so limited that it is
impossible to obtain a clearance of 2in. between the stay-wire and adjacent
line-wires, even if the spindle positions are shifted slightly as mentioned in D
3001, a stay-crutch should be fitted as shown in Fig. 16.
41. The points at which the stay and crutch are to be attached to the pole
should be carefully determined, to obtain the best possible clearance between
the stay and the line-wires. The stay should not, however, be attached
immediately above an arm if this can be avoided.
FIG. 15
STAY-SWIVEL IN OVERHEAD (OR GALLOWS) STAY
FIG. 16
STAY-CRUTCHES
42. Crutches are available in two sizes, viz. Crutches, Stay, No. 2, 19in.
long, for 4-way arms on poles of all types, and Crutches, Stay, No. 3, 34in.
long, for 6-way and 8-way arms on single poles.
43. Method of fitting stay-crutch. To fit the stay-crutch:-
-
Remove the bolt, distance tube, and thimbles, and fix the crutch
temporarily in position on the pole by driving two coach-screws through the
holes near the neck of the crutch.
-
Ascertain by measurement the length of wire required for the upper stay,
using a measuring tape or a length of sash-line and making allowance for the
twisting together of the two limbs of the stay between the pole and crutch
(the length of the upper stay should be such that, after it has been
made-off and bolted to the crutch, the latter will be inclined slightly
upwards at its outer end).
-
Make-off the ends of the upper stay, and the upper end of the main
stay-wire, to the thimbles supplied with the crutch (this work may
conveniently be done on the ground).
-
Attach the upper stay to the pole and, taking care to ensure that the
two limbs are exactly equal in length, secure it by means of two Staples,
Galvd., 2½in., driven into the pole
vertically above the coach-screws adjacent to the neck of the crutch (see
Fig. 16).
-
Twist the limbs together, as shown in Fig. 16, and, by means of the bolt
and distance tube, secure the thimbles, placing the thimble of the lower
stay in the central position.
-
If, with the wires attached, the crutch is not slightly inclined upwards
at its outer end, adjust it by increasing or reducing the number of twists
in the upper stay. Then, having made off the main wire to the stay-rod,
tighten it up, thus bringing the crutch into a horizontal position and
ensuring the tightening of the upper stay.
-
Finally, fit two coach-screws in the remaining holes to secure the
crutch permanently in position.
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FIG. 17 |
44. Trussing poles
In accordance with A 1901 and D 3001, single poles should be trussed only in
exceptional circumstances. As trussing is a means of strengthening the pole
only, stayblocks will usually be required in addition, to provide the necessary
foundation strength.
45. For trussing, a stay-rod, a length of stay-wire and a Spur, Pole (see
Table 1) are required. The stay-rod should be secured to the butt end of the
pole; the upper end of the wire should be attached to the pole at the resultant
point (see D 3001 and D 3026); the pole spur should be fixed midway between
these two points. The arrangement is illustrated in Fig. 17. (NOTE:
Stay-crutches should not he used for trussing poles.)
46. To truss a pole, proceed as follows:-
-
Fix the pole spur in position (see par. 45) by means of coach-screws.
-
Cut a groove in the side of the pole for the stay-rod. The depth of the
cut should be suitably increased towards the butt end to accommodate the
stay-rod in alignment with the fork of the pole spur (see Fig. 17). At its
lower end, the groove should be of sufficient depth to ensure an adequate
bearing surface for the stay-rod washer on the end of the pole.
-
Give the freshly-cut surfaces a liberal dressing of Creosote and Tar.
-
Fix the stay-rod as shown in Fig. 17(a), using, if required, one or more
taper washers (Washers, Galvd., No. 14) on the rod to provide a satisfactory
bearing surface for the stay-rod washer. Use a Nail, Rosehead, 3in. or a
coach-screw to secure
the washer, and a Staple, Galvd., in. at the upper
end of the groove to secure the rod.
-
Fit the stay-wire and adjust it (the instructions given in pars. 18 to
35 apply).
-
Bind the wire in to the fork of the pole spur, using Wire, Stay, 1/8 or
a strand from a short surplus length of stay-wire, as illustrated by Fig. 17
(b).
-
Fit stayblocks as detailed in C 3201.
47. Jointing (splicing) stranded wire
For staying purposes, jointless lengths of wire should generally be used. In
exceptional circumstances, however, where the use of a jointed stay-wire cannot
be avoided, splicing, as detailed in par. 49, may be resorted to.
48. Wire for bo'sn's chair
The method of splicing described in par. 49 should also be used for joining
together the ends of the 7/14 stay-wire used in the construction of the bo'sn's
chair, detailed in E 3143.
49. Method of splicing - 7-strand wire
Stranded wire should be spliced as follows:-
-
Apply a binding of Wire, Galvd., Binding to both wires (see A and B,
Fig. 18), at a distance of 18 in. and 31 in. from the end for 7/14 and 7/8
wire, respectively.
-
Unstrand the ends to the binding, and straighten the outer wires.
-
Leaving the centre wires (1 and 2, Fig. 18) straight, fan-out the outer
wires symmetrically around them as shown.
-
Remove the bindings, place each outer individual wire of one end between
two adjacent outer wires of the other, and push the ends of the stranded
wires together so that points A and B meet. During this operation the two
centre wires should be arranged so that they will be brought out at the
centre of the splice, and, when bent at right-angles for making-off in the
direction of the lay of the strand, one wire will cross over the other as
shown in the lower illustration of Fig. 18.
-
Pull the centre wires taut, and cross them ready for the first lappings.
-
Arranging the remaining free ends symmetrically, make-off each side of
the splice as detailed in pars. 28 and 29, binding the wires closely and
tightly to prevent slip.
50. Method of splicing - 4/8-stay wire
Splice in a similar way to 7-strand wire. 21in. of wire is required at each end
for making-off. For the first lappings, select a strand from each side which is
in a suitable position for crossing the other in the right direction and for
beginning the make-off as shown in the lower illustration of Fig. 18.
FIG. 18
JOINING TWO LENGTHS OF 7-STRAND WIRE
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