A flywheel, a cooling fan and a recoil starter are mounted on a crank shaft of an engine, thereby forming an engine unit. A rubber composition for breaker cushion comprises 1,3-bisbenzene and 25 to 35 parts by weight of carbon black having a nitrogen adsorption specific surface area of 70 to 120 cm2g based on 100 parts by weight of a rubber component. A high internal gradient magnetic capture structure may be on the transparent collection wall, magnets create an externally-applied force for transporting magnetically responsive material toward the transparent collection wall. The residence time of the monitoring device is correlated to the residence time of the filter cartridge by control of the fluid delivery parameters of the fluid delivery device. A metering mechanism is also provided which is capable of metering the material at a predetermined rate to the cutting blade.