power wrenches, but their fine holding power is easily lost under weather and service.
When spikes are pulled, the holes left in the ties are filled with tie plugs to protect the tie
from decay and to give good holding power to new spikes. Tie plugs made of a softwood are
preferred to those of hardwood. They fill the hole better and absorb moisture, swell, and split
less easily than hardwood ones. As shown in figure 3.13, the plugs have square heads and
rectangular shanks. They are designed to be driven into the tie to completely fill the top of the
spike hole which is usually enlarged from both the thrust of the rail against the spike and the
pulling of the spike.
Figure 3.13. Tie Plugs.
Figure 3.12. Screw Spike.
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