These jacks are made of two small and large arms, to be fixed on the back of wall frame and their duty is to control balance of frames. A type of this jack acts as load bearing structure in one- side framing and is used for bearing lateral force of concrete. These jacks are connected to soldier and floor by shafts in the beginning and end [terminal] parts. These jacks are double-screw types and are made of pipes in mid part; and, left turn- right turn threaded flange at the end, which makes it possible to adjust the length of the two screws and control the balance and straightness with precision.
