Комментарий к Шмот 26:26

בריחים are BOLTS, as the Targum translates it: עברין; in old French esparres.

בריחים חמשה, there would be five rings attached to each of the boards (planks) from the outside in order to slip the bolts or bars through them. In addition, in order to accommodate the בריח התיכון, the central bolt, each plank had to be hollowed where the hole was drilled to insert the central bolt therein.. As a result of all this the silver sockets at the bottom, the outside and interior bolts higher up and the clasps joining the planks together at the top, made for a solid structure once it had been assembled. According to the plain meaning of the text there were actually three bolts which qualify for the description בריח התיכון, “the central bolt.” One of them ran from north to south, and the other two ran from east to west parallel to each other on the two long walls of the Tabernacle. Seen in such a way, the Tabernacle was kept solid by the manner in which the corner planks were fitted to each other. This was achieved by the fact that the central bolts entered holes drilled from two directions in these two corner planks. According to the view of our sages (Shabbat 98) there was only one “central” bolt, and it described two turns when negotiating the two 90 degree turns at the northwest and southwest corners of the structure.

Each section being one fourth. . . [You might ask:] Why did Rashi divide it into three sections, [and say, “Placed at three equidistant places”]? He could have divided it [more simply]: from the top of the plank to the top bar is like from the top bar to the middle bar. And from the middle bar to the bottom bar is like from the bottom bar to the bottom of the plank — thus dividing it into four sections. [The answer is:] Both sides of the top bar are equal. From the top of the plank to the top bar is like from top bar to the middle bar. Therefore, these sides are considered as belonging to the top bar. Similarly, both sides of the middle bar are equal. From the middle bar to the top bar is like from the middle bar to the bottom bar. Therefore, these sides are considered as belonging to the middle bar. Similarly, the sides of the bottom bar are equal. From it to the middle bar is like from it to the bottom. Therefore, they are considered as belonging to it. That is why Rashi divided into three sections and not four. (Re”m)