Park tractor on level ground with the three-point hitch in its highest position. Disengage power takeoff, (PTO) and put tractor in neutral. Set the brake. Chock tractor wheels with large, flat-sided wood or stone wedges so that it cannot roll.
Place four jack stands under the edges of the mower deck while the three-point hitch is still in its highest position. Lower mower onto your jack stands. Leave as much room under the mower as possible so that you can crawl underneath it. Turn off the tractor ignition, and remove the key. This ensures that the tractor cannot be started accidentally while you work on the mower blades. According to finish mower retailer King Kutter, "Safety is a primary concern in the manufacture and design of our product. Unfortunately, our efforts to provide safe equipment can be wiped out by a single careless act of an operator or bystander."
Use a 2x4x12-inch block to jam the first blade against the left side of the mower frame when removing blades.
Use a 3/4-inch drive breaker bar with the correct size socket to remove the bolts, blade and washers. Place the bolts and washers back on the axle so they do not get lost while you remove the other blades.
Block the opposite end of the blade when you replace it. Remember the phrase, "Righty, tighty; lefty, loosey," when removing and replacing mower blades. Block the blade against the right side of the frame when replacing blades. Turn your sockets from left to right to remove bolts and from right to left to tighten them.
Replace blades using the block and the breaker bar in reverse. Tighten all nuts to the same torque as you would a lug nut on a car or truck.