Restraining device for reducing warp in lumber during drying

A loading device for courses of individual lumber pieces having a width and having edges having a height, in a lumber treatment operation that causes the lumber pieces to shrink, wherein the lumber pieces are arranged with the edges of adjacent lumber pieces side by side in at least one course of lumber pieces having a plane transverse to a vertical direction, the device comprising:

• a support for the at least one course;
• a rigid load member engaging at least portions of an outer side edge of a lumber piece at a first side of the at least one course;
• a rigid and moveable reaction member on a second opposite side of the at least one course and supporting a side of a lumber piece at an opposite side of the at least one course against loads applied by the load member;
• and
• a laterally extendible force generator providing a clamping force to move the reaction member toward the load member, wherein the at least one course between the load member and reaction member is loaded in compression that is parallel to wide faces of the lumber pieces to maintain a substantially consistent selected force parallel to the plane of the at least one course to hold the lumber pieces in the at least one course edge to edge continuously under the selected force during the lumber treatment operation, the load member and the reaction member thereby moving together by extending the force generator in a horizontal direction as the lumber pieces shrink, wherein the clamping force is sufficient to prevent warpage during the lumber treatment operation.