Riding lawnmower blade
First, always wear safety glasses and hand protection when working on machinery. Also include my favorite saying; "Common Sense Prevails". No amount of overgrown lawn is worth getting hurt. Work on as flat a surface as possible, always chock the tires in both directions to prevent movement and disconnect the negative battery cable making sure it will not contact either battery posts while working on the mower. This will insure the engine will not start on it's own or the mower move of it's own accord. Release the parking brake, with the shifter in "neutral" position. Check your tire chocks and make sure the mower is not going to roll in either direction. Now, lower the deck to it's lowest position. Now loosen any guide pins that extend from the underside of the main chassis that keep the belt from coming off the drive pulley on the engine. Again, there may be one or more. Remove the belt from the pulley. Now find the linkage that tightens the belt when you engage the blades. It should extend from the chassis at an angle to the deck. If your mower is equipped with a PTO (power take off) clutch that engages the blades by a switch on the dash, skip this step. Now remove the clips that secure the raising\lowering arms from the linkage at the top of the arms, not the deck end. This will allow you to slide the deck, slowly and carefully out from under the mower, with out the arms "dangling" from the mower interfering with the deck. You will have to adjust the angle of removal as you are sliding the deck as most have an "attack angle" that is not 90 degrees from the strait line of the mower from front to back, but is angled more forward on one side or the other. Once the deck is clear of the mower, depending on the size and weight you can lift it (with help) or use a floor jack to raise it (being VARY careful not to contact the blades) and lower it onto 4 blocks at least 4 inches high. Place the blocks at the 4 "corners" of the deck. Two blocks long enough to run past the length (front to back) on both sides of the deck will work as well. Remove the covers on both sides of the deck that cover the belt\pulleys on top of the deck by removing the bolts that secure them. Most are a self tapping type, some have nuts and washer on the underside, and some have studs welded to the deck, so you don't have to reach underneath. Some tractors have one of these covers, some two, and some non at all. Clean the top side of the deck with high pressure water from a garden hose, or a pressure washer if you have one. Be careful of flying debris. There may be rocks, pebbles or other items that can become flying missiles and injure you, or someone close by.Flip the deck over, again being careful not to trap your (or your volunteer's) hand between any moving parts and the deck (like between the sharp side of a blade and the deck housing) and place on your blocks in the same position. You can now access both the nuts holding the blades and the top side of the pulleys that either have nuts as well, or are made to accept a wrench or socket. Using a block of wood, ("2 x 4" x 12" is a good size but adjust the size to fit your particular deck) insert the block between the deck and one blade on the side of the blade that will stop it when loosening the nut holding the blade, making sure to get a good "bite" so it will not slip when pressure is applied. You can also use a wrench or socket on the pulley retaining nut on the top of the deck to stop the blade from moving as they both employ the same shaft. A volunteer to hold this is a good idea, perhaps a must. Make sure to equip them with safety gear as well. Apply a good lubricant like PB Blaster to the retaining nuts on the blades. Allow at least 15 minutes to absorb. Using either a 3/8" air gun or ratchet, or if using hand tools, a 1/2" breaker bar with the proper size socket of an impact grade, loosen the nut holding the blade. Your volunteer can help by hold the deck as you apply pressure to the bar. An extension of the breaker bar's handle with a piece of steel pipe having an inside diameter not much bigger than your breaker bar, and no more than a couple feet in length can be applied for more leverage, however this should only be done by someone with experience using the technique. Better to use air tools or a proper extension than bust up your hand by a slipping ad hock device. Remove the nut and washers, keeping them in the proper order for re-installation, and remove the blades noting which side is up and down. The cutting edge of the blade is always the lowest part of the blade when attached. Clean the underside of the deck. You may have to include a scraping tool as grass buildup can become quite hard over time and appear to be part of the deck. Pay special attention to moldy, wet grass around the blade shaft. This kind of moisture can induce corrosion prematurely to the deck housing and the bearings\shaft housing. Look closely for any type of wire, line from weed eaters, cables or any line that can be picked up by the mower and can wrap around the blade shaft between the blade and the deck. This line can eventually work it's way into the bearings, causing the bearings to fail. Carefully inspect the shaft, bearing and it's housing for damage, corrosion, etc. Repair\replace as needed. Remove any surface rust with a wire brush (hand or power) again watching for flying debris. Inspect the blades, looking for obvious impacts that have caused visible damage to the blades. If found, remove the blade shafts and check to be sure they haven't been bent. If they have, don't try to straiten them, but replace them. A bent shaft will have caused undue wear on the bearings, and a straitened shaft will be weak where the bend was. A failure of the shaft, bearings, or bearing housings can be fatal if the blade becomes detached and manages to fly out from under the mower while in use and strikes someone nearby. Now sharpen the blades, or replace them if needed. An experience blade sharpening service should be employed as the angle of the cutting edge and the level plane on which they travel is critical. Simply using a grinding wheel will not give you anything but a sharp piece of steel, but will cut unevenly. Clean any buildup from the blades and the shaft's mounting platform for the blades as rust or any foreign substance will cause the blades to be at an improper angle. While the deck is removed, inspect the holes where the raising\engaging linkages attach looking for wear to the hole or the linkage shaft. Replace if any undo wear is detected. Check for side to side movement of the pulley\blade shafts indicating a worn shaft or bearing. Replace if needed. Check the bearing housing the shaft travels through on the deck for electrolysis corrosion cause by dissimilar metals in a moist environment), cracks or other damage. Replace as needed. Inspect the deck belt for wear, cracking or age and replace if needed. It's always a good idea to replace it regardless when performing this deck//blade service. Reassemble in the reverse order of dis-assembly, using Loctite red on all threaded surfaces, and greasing any available grease fittings. Apply a coating of graphite lube or grease to the linkages where the attach to the deck an mower. Make sure all fasteners are tighten to proper specs. Lift the deck to it's highest setting, engage the parking brake, and reattach the battery. Start the mower and engage the blades checking for any undo noise indicating loose parts. Check the deck movement by lowering to different settings always listening and feeling for vibrations or noises. Should everything be in order, you may consider leveling the deck for optimum cutting performance. But that's a different question........
Best of luck, and please indicate your rating of this solution if appropriate.
Thanks so much,
Oct 18, 2008 |