There are several different types of lawn mower pulleys used on a riding style lawn mower. From engine and transmission-drive pulleys, to mowing deck pulleys and idler pulleys, there are many different sizes and types of pulleys that must be greased and maintained on a regular basis. There are three basic styles of pulleys used on the typical lawn mower: sealed bearing pulleys, greaseable bearing type pulleys and bearing free pulleys. Each style of pulley is used for a specific purpose and all contribute to the overall operational soundness of the machine.
All bearing-free lawn mower pulleys are attached to a solid steel shaft and are used to drive another pulley. The most common pulley of this type is found on the bottom of the lawn mower's engine in the form of the crankshaft pulley. These lawn mower pulleys are used to send power from the engine to the same type of pulley mounted on the transmission of the machine, thereby allowing the mower to propel itself across the lawn. These types of pulleys are often multiple grooved pulleys or stacked pulleys. This pulley design allows the engine to not only power the transmission, but to also send power to the mower deck via another separate drive belt.
Most of the pulleys on the typical riding lawn mower are found on the mowing deck. Each mower blade is equipped with an individual pulley, which is driven by the main mower deck belt. These pulleys are commonly sealed bearing pulleys, requiring no grease or servicing aside from keeping them clean and free of grass clippings. Allowing clippings to accumulate on and around the pulleys will cause overheating and bearing failure. A small brush, broom or an air hose can be used to remove the clippings and debris after each mowing.
Also found on the mower deck and used to maintain the proper belt tension to the cutting blade pulleys are the tensioner pulleys. These lawn mower pulleys are typically mounted to a steel plate and are spring-loaded to keep a constant pressure against the mower deck belt to prevent blade slippage. The tension of the spring pulling these pulleys taut is just enough to tighten the belt, but not so tight as to prematurely wear the sealed bearings of the blade pulleys. These tensioner lawn mower pulleys commonly use a greaseable bearing that requires service before each use.