DNA polymerase I translocates along the DNA strand by using the O-helix. This bends the template strand, with the binding of the next nucleotide to the primer strand causing the progression of the polymerase. The nucleotide within the O-helix (in the template pre-insertion site) is then moved to the binding site within the polymerase, causing a conformational change that allows the polymerase to advance along the template.
This process takes around 1 millisecond, enabling the polymerase to work quickly.