Forms the sliding-clamp-loader together with the small subunit (PubMed:10585481). Functions as an ATPase enzyme (PubMed:16800623, PubMed:18676368). The clamp loader holds the clamp in an open conformation and places it onto the DNA (PubMed:22194570, PubMed:18676368). 4 ATP molecules must bind to the sliding-clamp-loader before the latter can open the sliding clamp (PubMed:18676368). ATP hydrolysis triggers the detachment of the sliding clamp from the sliding-clamp-loader, freeing the sliding clamp to track along DNA (PubMed:18676368, PubMed:22194570). The sliding-clamp-loader consists of 4 large subunits and 1 small subunit (PubMed:2663867, PubMed:10585481). Interacts with the sliding clamp; this interaction allows the sliding-clamp-loader to open the sliding clamp (PubMed:22194570, PubMed:9395509). Part of the replicase complex that includes the DNA polymerase, the polymerase clamp, the clamp loader complex, the single-stranded DNA binding protein, the primase, the helicase and the helicase assembly factor (PubMed:16800624). Belongs to the Tevenvirinae sliding-clamp-loader large subunit family.