back spear

t. See back - speer. back-speed (bak'spēd), n. In mech., a second speed-gear of a lathe, which can be brought into action on the fore-speed, so that second series of speeds of the spindle are thereby obtained. back-speer (bak'spēr), v. t. [Sc., also written back - spear, -speir, [Scotch.]