Don't. If there is water on the slope or the road is muddy, just hang a low gear to refuel when climbing. The differential lock is to prevent the tire from slipping, and the differential between the axle and the wheel is to prevent the road from slipping seriously. When opened, the differential loses its function. Four wheels turn at the same time, and each wheel can scrape the ground. Only when there is much water and mud can it be opened for use, and it is not necessary to open it when climbing in normal road conditions.