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Jack Screws

The very early loggers had only hand tools to fall the big trees. Gunstick (to aim where the tree might land), axe, crosscut saw and wedges were the sum total of their tools. Once the tree was down it had to be bucked (cut into lengths) and peeled – again by hand. Finally the cut pieces had to be moved. What tool was used to move these huge logs? There was but one – a jack screw.

This is a description of a jack screw from a 1920’s piece we located.

“The jack screw was one of the most valuable pieces of equipment in the logging world. It varied in height, but was usually about two and a half feet high. The bar and gear were made of tool steel, with a frame of heavy piping.
The jack screw was much faster than a screw jack. A screw jack had a worm screw. It was very slow and almost impossible to use in logging. The jack screw was a piece of heavy pipe with a base like an inverted saucer. A bar with cogs in it, ran through the pipe. At the upper end of the bar was a "dog" on a swivel. This "dog" at the outer end of the bar was elevated slightly and very sharp, so as pressure was put on it, it would sink into the log. At right angles to the bar, were the gears, which fit into the cogs of the bar. The first gear was four to one plus the length of the handle; this went into a second gear that was about six to one plus the handle. With a man turning the jack screw, this ratio would be equal to the lifting power of forty men.

On the outside of the gear frame was a notched dog, which could lock the jack, so that you could leave it with any amount of weight on it for an indefinite period of time.

Just above the handle was an important safety device. This was a pin with notches. In case the logger slipped or accidentally let go of the handle, the pin fell into the notch and prevented the handle from flying around uncontrolled. A flying handle could cut a man in two, or severely injure him, to say the least.

Jack screws were used in all phases of logging. When logs were unloaded at the landing there would be two men, each with a jack screw. When a leg was to be moved into the dump, a jack screw would be placed beside the log, the log was quickly raised, and then the second man would place his jack screw and continue to assist the log in moving. The two men working alternately would quickly move the log any place that they wished the log to go. This was the general method for using a jack screw. When the oxen was pulling a load and a log was fouled in any way, a jack screw or two would be used by the suglar, assisted by one or both water slingers, if necessary.”

What did they look like? Here’s some pics we have collected to demonstrate.

Crosscut saw and gun-stick up against tree on the right. Axe, wedges and jack screw in the undercut.

Crosscut saw and gun-stick up
against tree on the right. Axe,
wedges and jack screw in the
undercut.

Jack Screw in the museum in Eureka

Jack Screw in the museum
in Eureka

Moving a log off of a flat car using jack screws as described above

Moving a log off of a flat
car using jack screws
as described above.