Lawn Tractor: Vibrates Excessively

Bearings are housed inside a stationary unit that allows the shaft to rotate within the housing. If a bearing becomes badly worn it can cause excessive vibration. To check the bearings, first remove your mower deck. Check the owner’s manual for your lawn tractor for instructions specific to your model. Next, remove the mandrel covers and belt then spin all the pulleys. You will want to listen for a growling noise and check for play, to determine that the bearings are worn. If the bearings are worn, you will need to replace the bearing in that unit. When it comes to mandrels, it is best to change out the entire mandrel with a new unit. To change the bearings, refer to instructions under mandrel replacement, listed above.

Your lawn tractor’s belts can become worn over time, and this can cause the belt to jump and shake all over the pulleys. To check the belt, remove the mower deck (be sure to follow your model’s instruction manual for exactly how to remove the deck, as this will vary from model to model). After you have removed the mower deck, remove the mandrel covers and pull the belt off. Check the belt for signs of cracking, brittleness, grooves, or any other general wear. If you discover any damage, you will need to replace the belt. Once you’ve replaced the belt, re-install the mandrel covers and mower deck.

The blades on your lawn tractor are designed to mulch and cut grass. A blade that is bent will cause excessive vibrations, and will either need to be straightened or replaced. To check for a bent blade, first remove the mower deck (check your owner’s manual to determine your model’s proper course). Once the deck is removed, turn the unit over and examine the blades. If your tractor is experiencing excessive vibrations, a bent blade should be noticeable. Replace the damaged blade by removing the hardware holding it in place, replacing it with a new blade, and tightening it down. Once this is complete, you can re-install the mower deck.

Over time, if a pulley in your lawn tractor has become worn, it can cause a bad vibration. To check your pulleys, start by removing the mower deck. Be sure to consult your operator’s manual for guidance in removing the deck, as it will be different depending on which model you have. With the mower deck removed, you can next remove the mandrel covers and belt, and check the pulleys for play and roughness when spinning. Check the pulley for concaved wear on the inside as well any other signs of damage. If you notice any of these signs, you should replace the pulley. To do this, attach an open-end box wrench on the back side of the pulley bolt as you loosen the hold down bolt. Then, remove the old pulley and replace it with a new one. To remove the mandrels, you can remove the hold-down bolt and secure the blade underneath using a piece of wood to prevent movement. Once you have replaced the pulley, you can re-attach the belt and mandrel covers, and re-install the mower deck.

The shaft is located inside the mandrel. If these shafts have excessive play they will need to be replaced. Start by removing the mower deck (refer to owner’s manual as many models differ in the way they are set up). Remove the belt and mandrel cover, then disconnect the blade from the mandrel and remove the hold-down bolts. With the mandrel removed, unscrew the nut holding the pulley in place, then remove the pulley, the collar, and the dust cover. At this point, the shaft should pull right through. Replace with a new shaft, reinstall the dust cover, collar and pulley, and tighten the pulley back down. Re-install the mandrel back onto mower deck, then re-install the blade, belt, and mandrel covers and reattach the mower deck.

The mandrel is a housing unit for bearings, and a shaft used to transmit rotary power from one end to another. If the mandrel is badly worn, it will have play at the shaft ends, causing a vibration. To check for play, first remove your mower deck. Once removed, spin all the mandrels, and listen for growling noises and check for any play. If you notice any of these symptoms you will need to replace the mandrel. To accomplish this, remove the cover over the pulley on the mandrel, then remove the belt and the blade under the mower deck and remove the bolts holding the mandrel in place. Now you can re-install the new mandrel, pulley, belt, and blade. Finally, re-install mower deck and your repair should be complete.