Figure 6-56. - Lashing for shears.
position when the shears have been raised, but will be out of the way during erection.
b. If the shears are to be used on heavy lifts, another tackle is rigged in the base guy near its anchorage. The two guys should be secured to the top of the shears with clove hitches to legs opposite their anchorages above the lashing.
c. Several men (depending on the size of the shears) should lift the top end of the shear legs and "walk" them up by hand until the tackle on the rear guy line can take affect. After this, the shear legs can be raised into final position by hauling in on the tackle. Secure the front guy line to its anchorage before raising the shear legs and keep a slight tension on this line to control movement. (See fig. 6-57.)
d. The legs should be kept from spreading by connecting them with rope chain, or bards. It can be necessary, under some conditions, to anchor each leg of the shears during erection to keep the legs from sliding in the wrong direction.
3. Operating. The rear guy is a very important part of the shears rigging, as it is under a considerable strain when hoisting. The front guy has very little strain on it and is used mainly to aid in adjusting the drift and to steady the top of the shears when hoisting or placing the load. It maybe necessary to rig a tackle in the rear guy for handling heavy loads. In operation, the drift (inclination of the shears) desired is set by adjustment of the rear guy, but this should not be done while a load is on the shears. For handling light loads, the fall line of the tackle of the shears can be led straight out of the upper block. When heavy loads are handled, you should lash a snatch block (fig. 6-58) near the base of one of the shear legs to act as a leading block, The fall line should be run through the leading block to a hand- or power-operated winch for heavy loads.Continue Reading