A centralizer for centralizing a pipe is provided which collaborates the spring force of its bow springs. The centralizer includes a pair of end collars, and at least one center collar. Each of the collars has a center hole for coaxially receiving a pipe. In addition, the centralizer includes a plurality of longitudinally extending and arcuate bow springs having ends which affix to the end collars. The centralizer includes linkage arms which connect the center collar to the bow springs. The linkage arms may provide additional outward spring force against the bow springs. Preferably, the centralizer includes a mechanism for forcing the bow springs radially inward from their at rest position.
