Look for the closest horizontally positioned limb over the split or break in the tree. Take hold of the top pulley of the block and tackle. Attach the top pulley to the horizontal limb. Take the block and tackle rope in both hands and pull on it. The rope should pull together the two broken halves of the trunk.
Wrap a length of rope around the trunk. Position the rope close to the top part of the break or split. Tie the rope in a square knot to keep the two tree pieces secured together.
Measure the length of the split with a measuring tape. Divide that measurement into thirds, and make three appropriate marks up the length of the tree. Attach a 1/2-inch diameter drill bit to an electric drill. Drill through the tree on either side of the split along each of the three marks.
Use a hammer to tap a 1/2-inch bolt into each of the holes. Secure each bolt with a washer and nut, and tighten them with a wrench. Take off the block and tackle.
Examine the tree over the course of several months. If the tree shows visible signs of healing, take off the knotted length of rope after six months.