Abstract: A riding lawn mower having covers for covering the side part of a cutter deck and the side part of a transmission section. The covers have a plurality of small holes formed in a portion facing the side part of the cutter deck. The accumulation of grass clippings on the upper surface of the cutter deck and the transmission section is reduced, and the state of accumulation of grass clippings is confirmed via the small holes.

Abstract: A walk-behind working machine includes a first clutch mechanism for connecting or disconnecting drive between an engine and a working member of the working machine. The first clutch mechanism includes a first clutch lever having a first activating member. A second clutch mechanism is configured to connect or disconnect drive between the engine and traveling members of the working machine. The second clutch mechanism includes a second clutch lever having a second activating member. A throttle regulating mechanism has a pivoting member for engagement with one of the first activating member of the first clutch mechanism and the second activating member of the second clutch mechanism so as to undergo pivotal movement to shift a throttle for the engine from a first opened position in which an idling engine speed is produced to a second opened position in which a working-machine-activating engine speed is produced.

Abstract: A riding lawn mower having covers for covering the side part of a cutter deck and the side part of a transmission section. The covers have a plurality of small holes formed in a portion facing the side part of the cutter deck. The accumulation of grass clippings on the upper surface of the cutter deck and the transmission section is reduced, and the state of accumulation of grass clippings is confirmed via the small holes.

Abstract: A lawn mower having upper and lower cutter blades in a cutter housing is provided. The blades are disposed with a phase difference such that upper blade edge parts of the upper cutter blade are advanced forward with respect to lower blade edges of the lower cutter blade in the rotation direction, whereby interference of the upper cutter blade with the air-lifting parts of the lower cutter blade is avoided, and the noise produced by the rotation of the upper and lower cutter blades is reduced.

Abstract: A bush cutter has a driving bevel gear housed in a first box constituting a part of a gearbox, and a driven bevel gear housed in a second box and engaging the driving bevel gear. The driving bevel gear is rotatably retained in a first bearing. The first bearing is screw-fitted into the first box movably in an axially longitudinal direction of the driving bevel gear. Rotation of the first bearing causes the driving bevel gear to move in the axially longitudinal direction to finely adjust the engagement of the driving bevel gear with the driven bevel gear.

Abstract: A bush cutting machine with a tubular operating pole connected to an outlet of an exhaust muffler and doubling as an exhaust passage is provided. Exhaust gases discharged from an engine flow from the exhaust muffler through the operating pole and are then discharged into the air. The substantial capacity of the exhaust muffler is increased by the operating pole, and the exhaust noise of the engine is reduced.

Abstract: A vegetation cutting machine has a tubular operation rod, a motor mounted to an end of the operation rod, a drive shaft extending through the operation rod and driven by the motor, a cutting tool provided at a distal end of the operation rod to undergo rotation with the drive shaft, a handle mounted on the operation rod, and a pair of handgrips provided on distal ends of the handle. Each of a pair of fastener members traverses the handle and a respective one of the handgrips for fixedly mounting the respective handgrip to the handle at a point located substantially at a center of gravity of a sum of a mass of the respective handgrip and a mass of a portion of the handle extending between the fixing point and a respective one of the distal ends of the handle, such that the fastener members of the respective handgrips are located at positions of the handle at which vibrations transmitted to the handle from the motor through the operation rod are minimized.

Abstract: A walk-behind working machine includes a first clutch lever, a second clutch lever, and a throttle having a degree of opening controllable by each of the first clutch lever and the second clutch lever. The working machine also includes a pivoting member, a throttle wire connected to the pivoting member, and a first activating member provided to the first clutch lever for engagement with an engagement member provided to the pivoting member. When the first clutch lever is operated to place a first clutch in a connected state, the throttle is shifted by operation of the first clutch lever from a first opened position in which an idling engine speed is produced to a second opened position in which a working-machine-activating engine speed is produced.

Abstract: A lawn mower having upper and lower cutter blades in a cutter housing is provided. The blades are disposed with a phase difference such that upper blade edge parts of the upper cutter blade are advanced forward with respect to lower blade edges of the lower cutter blade in the rotation direction, whereby interference of the upper cutter blade with the air-lifting parts of the lower cutter blade is avoided, and the noise produced by the rotation of the upper and lower cutter blades is reduced.

Abstract: A drive shaft extends into a tubular member for use in a portable working machine. The drive shaft is mounted relative to the tubular member so as to undergo rotation relative to the tubular member. The drive shaft has a longitudinal axis and resin bushes integrally mounted on the drive shaft for rotation therewith at positions along the longitudinal axis corresponding to vibration nodes of the drive shaft. Each of the resin bushes has an outer peripheral surface disposed in slidable contact with an inner peripheral surface of the tubular member.

Abstract: A bush cutting machine with a tubular operating pole connected to an outlet of an exhaust muffler and doubling as an exhaust passage is provided. Exhaust gases discharged from an engine flow from the exhaust muffler through the operating pole and are then discharged into the air. The substantial capacity of the exhaust muffler is increased by the operating pole, and the exhaust noise of the engine is reduced.

Abstract: A vegetation cutting machine has a tubular operation rod, a motor mounted to an end of the operation rod, a drive shaft extending through the operation rod and driven by the motor, a cutting tool provided at a distal end of the operation rod to undergo rotation with the drive shaft, a handle mounted on the operation rod, and a pair of handgrips provided on distal ends of the handle. Each of a pair of fastener members traverses the handle and a respective one of the handgrips for fixedly mounting the respective handgrip to the handle at a point located substantially at a center of gravity of a sum of a mass of the respective handgrip and a mass of a portion of the handle extending between the fixing point and a respective one of the distal ends of the handle, such that the fastener members of the respective handgrips are located at positions of the handle at which vibrations transmitted to the handle from the motor through the operation rod are minimized.

Abstract: A bush cutting machine including a prime mover, a cutter and a handle fixed to an operation rod. The handle has left and right end portions carrying grips. Each grip is mounted at a center of gravity of a sum of a mass of a handle portion between a fixed point and a distal end of the handle and a mass of the grip.

Abstract: A bush cutter has a driving bevel gear housed in a first box constituting a part of a gearbox, and a driven bevel gear housed in a second box and engaging the driving bevel gear. The driving bevel gear is rotatably retained in a first bearing. The first bearing is screw-fitted into the first box movably in an axially longitudinal direction of the driving bevel gear. Rotation of the first bearing causes the driving bevel gear to move in the axially longitudinal direction to finely adjust the engagement of the driving bevel gear with the driven bevel gear.

Abstract: A plant cutter apparatus has a tubular handling rod having a first end portion and a second end portion. A drive shaft extends through the handling rod and is mounted for undergoing rotation. A drive source unit is mounted on the first end portion of the handling rod for rotationally driving the drive shaft. A cutter blade is connected to the drive shaft for rotation therewith. A clutch case has a first mounting portion connected to the first end portion of the handling rod, a flexible coupling portion extending from the first mounting portion toward the drive source unit, and a second mounting portion extending from the flexible coupling portion and connected to drive source unit. The second mounting portion has an axial fitting hole for receiving the first end portion of the handling rod so that the first end portion of the handling rod is axially slid able therein.

Abstract: A bush cutting apparatus has a first rotational shaft mounted for undergoing rotation and a cutter blade connected to the first rotational shaft for rotation therewith. A clutch mechanism has a rotational member, at least one clutch moving member mounted on the rotational member for undergoing movement along a radial direction of the rotational member, a clutch drum mounted on the first rotational shaft for sliding movement therealong to engage the clutch moving member, and a clutch resilient member for biasing the clutch moving member toward an axial centerline of the rotational member. A brake mechanism has a brake shoe formed at an end portion of the clutch drum, a brake pad disposed opposite to and confronting the brake shoe, and a braking resilient member for biasing the brake shoe into pressure contact with the brake pad.

Abstract: A plant cutter apparatus has a one-piece handling rod having an outer pipe portion, an inner pipe portion disposed concentrically within the outer pipe portion, and first, second and third radial stay portions extending between and interconnecting the outer pipe portion and the inner pipe portion. The first, second and third radial stay portions are arranged at non-equal angular intervals such that an angle &thgr;1 formed between the first and second stay portions, an angle &thgr;2 formed between the second and third stay portions, and an angle &thgr;3 formed between the third and first stay portions differ from each other. A drive shaft extends through the inner pipe portion and is rotatably supported within the inner pipe portion via a bushing disposed between the drive shaft and the inner pipe portion. A drive source unit is mounted at one end of the handling rod for rotating the drive shaft.

Abstract: Drive shaft of a plant cutter apparatus includes an elongate main shaft portion made of a titanium alloy, and end shaft portions made of steel and integrally joined to the opposite ends of the main shaft portion. The titanium alloy has substantially the same mechanical strengths as the steel. Therefore, the titanium-alloy-made main shaft portion can secure rigidity that is normally required of the plant cutter's drive shaft, and can also reduce the weight of the drive shaft to thereby minimize unwanted sagging-induced vibrations of the drive shaft caused by the shaft's own weight.

Abstract: A drive shaft to be inserted into a pipe-shaped operating pole for use in a portable working machine is provided. The drive shaft has at least one resin bush integrally formed on its outer peripheral surface. Thus integrally forming the bush on the drive shaft allows agreement between the axis center of the operating pole, the axis center of the bush and the axis center of the drive shaft, preventing the change of position of the bush during the use of the working machine, and resulting in the reduction of vibration of the drive shaft with the simple configuration.

Abstract: A handle holder for mounting a U-shaped handle to an operating pole of a bush cutting machine. The handle holder has a first holding member and a second holding member. The first holding member has an operating pole insertion hole for insertion of the operating pole therethrough, an oblique groove, and a handle receiving groove for receiving the base of the handle. The second holding member has a wedge and a handle retaining groove. The wedge is fitted into the groove of the first holding member to fix the first holding member to the operating pole. The handle is interposed and held between the handle receiving groove of the first holding member and the handle retaining groove of the second holding member to be fixed to the first holding member.