Abstract SMARCAL1, ZRANB3 and HLTF are all required for the remodeling of replication forks upon stress. Using reconstituted reactions, we show that the motor proteins have unequal biochemical capacities, explaining why they have non-redundant functions. Whereas SMARCAL1 uniquely anneals RPA-coated ssDNA, suggesting an initial function in fork reversal, it becomes comparatively inefficient in subsequent branch migration. We also show that low concentrations of RAD51 and the RAD51 paralog complex, RAD51B-RAD51C-RAD51D-XRCC2 (BCDX2), directly stimulate SMARCAL1 and ZRANB3 but not HLTF, providing a mechanism underlying previous cellular data implicating these factors in fork reversal. Upon reversal, RAD51 protects replication forks from degradation by MRE11, DNA2 and EXO1 nucleases. We show that the protective function of RAD51 unexpectedly depends on its binding to double-stranded DNA, and higher RAD51 concentrations are required for DNA protection compared to reversal. Together, we define the non-canonical functions of RAD51 and its paralogs in replication fork reversal and protection.