A bar clamp includes a handgrip; a fixed jaw carrier; a slide bar comprising two opposite wing members; a moveable jaw carrier and comprising a transverse channel, a trough extending from center of the channel to one end of the channel, a bottom recess, and two opposite stop members in the recess wherein the slide bar passes the channel with the wing members being stopped by the trough in a locked position; and a U-shaped spring-actuated lock assembly in the recess and comprising inverted U-shaped opposite first and second lock members being engaged with the wing members in the locked position, and first and second projections between the lock members and a bottom of the lock assembly and being engaged with the stop members in the locked position. Pushing the locking assembly until being stopped will disengage the lock members from the wing members.