This is about removing the lower branches of a tree to produce a branch free wood. I don’t see this kind of work happening anywhere anymore in years. Pruning can be useful in the production of quality wood. Especially poplars (mostly Populus × canadensis) were however crow lifted.
Of a branched trunk or head (fork, sometimes three peaks) only the straightest is left. The idea is that the volume increase in wood is not realized in unusable branches, but in the valuable strain (lumber). (For coppice so this is not necessary.)

For trees on the outside of a plot, it was more often and more necessary. Inside there is less light and less branch development by closed position. When we were asked a price per piece or per hour, it was very important to take this into account. Especially in small lots (lots of outside trees). I think it makes sense to get a good quality of long beams. Especially in young trees. You can then still steer something with pruning shears, hand saw, pole saw or ladder.
It was customary to do so during the autumn. Other seasons too. Experienced farmers allowed to do it even in August, then there came less and less thick shoots afterwards.

sporenIf we had to work at high altitude(12 to 20m) or had thick branches to cut off (a fork of the crown), then we used spurs to climb in the tree. The word refers to an analogy with spurs of a cock or chicken leg.

We had two types. An iron ran from below the knee along the inside of the leg at an angle of 90° under the foot. At that corner, diagonally downwards, was a sharp pin. That you hit when climbing in and through the bark. Preferably not too deep which gave unsightly brown spots in the wood. The pins are always naturally tight enough by your own weight. There was a mounting strap around the foot, and one around the lower leg. The latter had a wide belt of at least 15 cm, in order to prevent painful incising.

In the second type was a vertical iron to the outside of the leg. I found the first a little easier. That you could more or less hang. Furthermore, the equipment consisted of a wide belt with D - rings, plus a thick rope around the tree that with a snap was hooked to hang on the tree during work. And a good bracket to hang a cleaver. Because if it dropped, you could again get on and off. And believe me, it was heavy stuff.
When climbing you had to try to hang with your ass as much as possible back out of the trunk. As a beginner you tried standing close along the trunk to get up. That does not work, and you get cramped. It is better on a monkey way. That's why you chose to climb even the inclined (lower) side of the tree where you could hang on. With your weight you came anyway to that side. The security rope pulled up with you at every step. There was a sort of garden hose around to facilitate the sliding on rough bark and as additional protection against caps (accidentally). On the way up, all the branches were cut away flat to the trunk. Well making sure that there were no protrudings remaining. Since the rope at the (fast) descending could catch behind and then you hit with your facade against the trunk. So the branch was first slashed from below against the tearing, and then hacked from above. Be very careful that you don’t hit the safety rope...
In descending it was mainly hooked with the legs alternately wide out, and then swinging then alternatively to the stem. The spores naturally hit trough the bark, without using force. Soaring is better with small and fall with great strides. Recent fast-growing species have a much thinner and less sturdy bark. To cut off thick branches we left the wreath (crown, branches ring) just below usually still standing, so that we could rely on and stand there.

We had for younger trees and small branches a pipe system with 3 tubes of 3 meters, 1 of 1 meter and 1 of 2 meters. With the 2 meter that we could achieve ourselves we could do so all combinations up to 15 meters. They were light aluminum tubes with a steel sleeve as connector to put fixed with two screws in each part. On top there was a heavy steel rod, the hammer. Around this was a steel pipe with a long groove. A screw in the hammer rod gave 50 cm sliding and chopping space through the groove. On top was the wide blade of an ax. That you put under a branch, and then hammered the ax right through it. The final knock you did with much force, so that the branch jumped of the tribe up and felt down. Otherwise, there was a chance that it hit you down when it come down, and with that last jump, it falls behind you. I once thought that my father was easy resting against a tree, while I was at toil. Later I heard that he was beaten knockout awhile. (Helmets we used at that time neither.) It was hard work. Pure fitness. You got muscles of steel. And a thick neck. And stiff. You had to look up steep constantly. Just try to do it one day.
In addition to the chopper, there was also a hook. Convenient to pull off loose branches but especially to hang the rod a little while to rest. Just putting upright the set of 9 meters or longer stake was heavy work. The more he was out of balance, the much he weighed heavier. And then he swung more if he was longer. So you always tried to keep him pretty right. And keep looking up. But while I’m writing this I'm beginning to understand why no one apparently does it anymore...