28. Two people will place a foot on each leg of the A-frame to prevent it
from moving and two people lifting the A-frame from the top center to raise
it. One person helps raise the A-frames by placing the cable around his
waist and backing up. As it is being raised, two persons at the base can
reach out and help bring it to a full upright position.
29. While the A-frame is being held in place, it is checked to be sure it
is in a true vertical position and that the cable coming over the top of it
is in line with cable already installed. The legs should be aligned at this
time.
If there are no corrections, then the second A-frame is inserted
beneath the first one.
There should be little or no air gap between the
boards and no movement is permitted.
30. Your work is not finished yet. Now, you drive a stake in the ground
at the base of each leg at an approximate angle of 45 degrees.
You then
take marline cord, starting with a clove hitch on the stake, wrap the cord
between the stake and A-frame leg, being sure to cross over each way making
an X in the cord between the A-frame leg and the stake. This will help to
keep the legs of the A-frame in place.
One final step is to take a long
piece of marline cord or white engineer tape and secure the legs together.
Start on one leg with a clove hitch and move to the next leg passing the
marline cord or engineer tape around the leg pulling it taut and continuing
along until you reach the starting point. Tie a square knot. Recheck all
work.
31. A disadvantage to A-frames is the time needed to construct the A-frame
and erect it with the cable attached.
Then you must cross the road and
construct the one over there. All this time the cable is laying across a
major highway. The cable could be damaged before you get it in the air to
protect it.
32. Sag is an important part of crossing a road. First of all, the cable
must be at least 18 feet above the road at the center of the sag if it is
crossing a primary road.
Only 14 feet clearance is needed for secondary
roads. As a general rule, use the information presented in Table 2-1.
Table 2-1.
Amount of sag.
2-7
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