One method uses a large
Acme thread (24 inches long by 1 1/4 inch in diameter) attached to an 18-inch T-bar handle.
The back end of the 762-SDN-6, showing the
Acme thread section, and the locking button.
At the inferior part of the axle 4 is mounted the bushedbearing 6, free on the axle, fitted with a coarse pitch exterior
acme thread (90 mm).
Available for any UN, UNJ, Buttress, Metric, or
Acme thread greater than 3".
The
Acme thread form has a 29-degree thread angle and a large flat at the crest and root (see Fig.
The
acme thread lead accuracy of the lifting screw is better than 0.003 in.
In Hock's case, he needed to put a 2-pitch internal
Acme thread in a 14" I.D.