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P.O. ENGINEERING DEPT
ENGINEERING INSTRUCTIONS
LINES
OVERHEAD
C3202
Issue 1, 19.5.65
POLING
Sheerlegs, Pole Raising
Description, Use and Maintenance
I. General
This Instruction describes the use of Sheerlegs, Pole Raising as a mechanical
aid for erecting 28ft. to 32ft. poles. Maintenance is also covered.
2. Description
The sheerlegs are portable and consist of two light metal tubular legs to which
are attached pulley blocks and tackle giving a mechanical advantage of 4 to 1.
The pulley blocks are attached to the pole with a chain hitch and the tackle is
a wire rope of high tensile steel, 14mm approximate circumference, 6/24 strand,
ultimate breaking strength 3000lbs. The pulley blocks and wire rope are attached
to a winch which is mounted on one of the legs and is operated by a long cranked
handle. A ratchet is fitted to the winch to sustain the load and may be released
for unwinding the wire rope. Spikes are fitted to the sheerlegs to prevent
slipping. The maximum safe load for the sheerlegs is 770lbs.
3. Number of men required. The actual operation of erecting
poles using the sheerlegs is within the capacity of two men but other
considerations, such as the necessity to carry the poles, may determine the
minimum number of men required (see C 3201).
FIG. 1
METHOD OF USE
4. To erect a pole.
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Set a pole sliding board or digging bar in the hole and
place the butt of the pole against it so that the pole cannot slip as
lifting commences.
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Lay the sheerlegs along the pole with the apex at the butt
end and one leg on each side of the pole and with each foot about 5ft. from
the pole (see Fig. 1).
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Fit the hitch on the pole at a point on the line between the
feet of the Sheerlegs (see Fig. 1). If this is not done it will be
difficult to keep the sheerlegs upright when raising the pole. The centre of
gravity of the pole should always be on the butt side of the hitch. A good
clearance between the pulleys is necessary to avoid jamming (see Fig. 2).
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Raise the sheerlegs to the vertical and ensure that the feet
are firmly based and will not slip as the pole is raised and as the
sheerlegs lean from the vertical.
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Raise the pole by operating the winch and the sheerlegs will
become self-supporting due to the weight of the pole on the wire rope. As
the pole is raised further, the sheerlegs will lean towards the pole hole
(see Fig. 3). When the top of the pole is high enough, the butt will slide
gently into the hole.
FIG. 2
5. Setting the pole. When the butt is resting on the bottom of
the hole use the handles at the lower end of the sheerlegs to set the pole in a
vertical position (see Fig. 4). Use the sheerlegs to hold the pole firmly in the
required position during back-filling and punning (see C 3201).
6. Releasing the sheerlegs. When the pole is up and back-filling
is completed, slacken off the winch and when the sheerlegs have been lowered to
the ground the hitch on the pole will loosen itself and slide down. It can then
be removed.
FIG. 3
FIG. 4
7. Precautions during storage and transport.
To avoid kinking the wire rope when it is not in use close the Sheerlegs and
pull the pulley blocks to foot of the legs. Secure the chain on the pulley
blocks to the handles and wind the wire rope onto the wine until a slight
tension is obtained.
MAINTENANCE
8. Lubrication of wire rope
Oil, Bearing, No. 13 should be wiped over the rope once a fortnight to prevent
rusting.
9. Inspecting for safety.
The rope should be inspected frequently and when it shows signs of flattening,
corrosion, or any other defect or if, in any length of 2 inches, the total
number of visible broken wires exceeds five, the rope should be replaced. A
detailed inspection of the Sheerlegs should be made every six months.
10. Renewal of the wire rope
This should only be done at a Mechanical Aids Centre. Replacement wire ropes may
be purchased from the makers, W. A. Lloyds Alloys Limited, Clyde Works,
Droitwich, Worcs. The ropes are listed in the manufacturer's spare parts list as
Part No. 16. The method of removing and replacing the rope is shown in Figs. 5
and 6.
FIG. 5 REMOVING THE WIRE ROPE
FIG. 6 REPLACING THE WIRE ROPE
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