Abstract: A concrete vibrator can automatically change the rotational speed of a motor depending on the state of a vibrating tube. Under control by a controller, the concrete vibrator is operated in a normal mode in which the motor is supplied with driving power having a frequency to make the motor rotate at a rotational speed suitable for air bubble removal, or in an idling mode in which the motor is supplied with driving power having a frequency to make the motor rotate at a lower rotational speed than in the normal mode. The controller measures, per unit of time, a value of a current that is input to the controller or motor, compares a latest current value to a reference value calculated based on a past measurement value, and compares an absolute value of the comparison value to a threshold to grasp the state of the vibrating tube.

Abstract: Provided is a concrete vibrator capable of automatically changing the rotational speed of a motor depending on the state of a vibrating tube and suitably avoiding overheating of the motor and a failure due to the motor overheating. Under control of control means 8, the concrete vibrator is operated in a normal mode in which a motor 2 is supplied with driving power having a frequency that can make the motor 2 rotate at a rotational speed suitable for an air bubble removing process, or in an idling mode in which the motor 2 is supplied with driving power having a frequency that can make the motor 2 rotate at a rotational speed lower than the rotational speed in the normal mode.

Abstract: A fall detection sensor for a rammer includes an acceleration sensor, a low-pass filter, an integrator, a first comparator, a second comparator, and control means. The second comparator compares wave patterns of input signals with a plurality of types of fall sample waves and non-fall sample waves stored in advance. The second comparator outputs a fall detection signal upon determining that the rammer has fallen when the similarity with one of the fall sample waves exceeds a threshold, and the second comparator outputs a non-fall signal upon determining that the rammer has not fallen when the similarity with one of the non-fall sample waves exceeds a threshold.

Abstract: Provided is a fall detection sensor for rammer capable of determining a fall state of a rammer, that operates with a large vibration and impact, with high accuracy, and stopping a motor (an engine or the like) immediately. The fall detection sensor for rammer includes an acceleration sensor (2), a low-pass filter (3), an integrator (4), a first comparator (5), a second comparator (6), and control means (7). The second comparator (6) compares wave patterns of input signals (x?-z?) with a plurality of types of of fall sample waves (FW) and non-fall sample waves (NFW) stored in advance. The second comparator (6) outputs a fall detection signal (fs) upon determining that the rammer has fallen when the similarity with the fall sample wave (FW) exceeds a threshold, and the second comparator (6) outputs a non-fall signal (nfs) upon determining that the rammer has not fallen when the similarity with the non-fall sample wave (NFW) exceeds a threshold.

Abstract: A box-shaped protective cover that covers an upper structural portion of a body of a vibrating compactor is manufactured by executing a cutting process for fashioning a single metal plate into a shape including a first planar portion, a second planar portion, an intermediate portion, and a plurality of side flaps, a bending process for bending or curving the side flaps and the intermediate portion, and a welding process for welding a side flap of the first planar portion to a side flap of the second planar portion.

Abstract: The present invention provides a method of manufacturing a sufficiently strong, box-shaped protective cover for a vibrating compactor inexpensively using a small number of processes and only simple processes, and provides a protective cover for a vibrating compactor. A box-shaped protective cover that covers an upper structural portion of a body of a vibrating compactor is manufactured by executing a cutting process for fashioning a single metal plate into a shape including a first planar portion 1, a second planar portion 2, an intermediate portion 3, and a plurality of side flaps 5 (5a to 5d), a bending process for bending or curving the side flaps 5 and the intermediate portion 3, and a welding process for welding a side flap 5a (or 5b) of the first planar portion 1 to a side flap 5c (or 5d) of the second planar portion 2.

Abstract: A cutting apparatus has a main body including a body frame, wheels, a motor and a blade; a blade cover; and a slide guide. A cutting depth of the blade is adjustable. A blade cover casing entirely covers the blade. A slider having left and right linear portions is attached to a rear surface of the casing. The slide guide has circular-arc portions and flaps for sandwiching the linear portions of the slider. A gap is formed between the flaps and a side surface of the body frame. By sandwiching the linear portions of the slider between a flap and the body frame, and sandwiching the circular-arc portions between the left and right linear portions, the blade cover can slide in the up-down direction with respect to the slide guide and the body frame and can rotate about the circular-arc portions.

Abstract: A dust collection device for a concrete cutter includes a suction duct disposed on an upstream-most side; a plurality of dust collectors of a cylindrical cyclone system disposed in series downstream of the suction duct; and a plurality of dust collection chambers connected respectively to the plurality of dust collectors and storing individually dust separated in each of the dust collectors. A blower is disposed between any two of the plurality of dust collectors and performs intake and discharge of air by rotation of a built-in fan. A return flow channel communicates the suction duct with the dust collection chamber which is connected via a connection portion to a dust collector disposed on a downstream-most side from among the plurality of dust collectors, or a return flow channel communicates the suction duct with the connection portion.

Abstract: A cutting apparatus has a main body including a body frame, wheels, a motor and a blade; a blade cover; and a slide guide. A cutting depth of the blade is adjustable. A blade cover casing entirely covers the blade. A slider having left and right linear portions is attached to a rear surface of the casing. The slide guide has circular-arc portions and flaps for sandwiching the linear portions of the slider. A gap is formed between the flaps and a side surface of the body frame. By sandwiching the linear portions of the slider between a flap and the body frame, and sandwiching the circular-arc portions between the pair of left and right linear portions, the blade cover can slide in the up-down direction with respect to the slider guide and the body frame and can rotate about the circular-arc portions.

Abstract: A dust collection device for a concrete cutter includes a suction duct disposed on an upstream-most side; a plurality of dust collectors of a cylindrical cyclone system disposed in series downstream of the suction duct; and a plurality of dust collection chambers connected respectively to the plurality of dust collectors and storing individually dust separated in each of the dust collectors. A blower is disposed between any two of the plurality of dust collectors and performs intake and discharge of air by rotation of a built-in fan. A return flow channel communicates the suction duct with the dust collection chamber which is connected via a connection portion to a dust collector disposed on a downstream-most side from among the plurality of dust collectors, or a return flow channel communicates the suction duct with the connection portion.

Abstract: The present invention provides a safety device of vibration roller wherein a travel switching device of the roller is switched to a neutral position automatically and the roller stops automatically when the operator is caught between the roller and an obstacle, and a safety switch is activated, even if the travel lever is placed in the reverse position continuously. A back end (16a) of an outer tube of an operation cable (7) is locked in front of the travel lever (4) in the case (2) when a safety switch (22) is not activated, the back end (16a) of the outer tube is released and displaced to a direction of the travel lever (4) when the safety switch (22) is activated.

Abstract: An engine stop switch and a fuel open-close lock are accommodated in a throttle lever case so that they can be easily disassembled, and the engine stop switch is turned on and off and the fuel open-close cock is opened and closed adequately by the actuation of a rotary valve in response to the turning of a lever. An engine stop switch and a fuel open-close lock are integrally incorporated in a throttle lever case, a partially toothless driven gear is intermittently rotated via a partially toothless drive gear rotated by a lever, and the intermittent rotation of the partially toothless driven gear turns on/off the engine stop switch and opens/closes the fuel open/close cock.

Abstract: The present invention provides a protective cover structure for a rammer for which a guard cover plate of a power engine in a rammer is molded from a synthetic resin allowing any shape to be freely obtained and having small weight, high strength, and impact absorption ability. The cover plate is configured so that it can be assembled and disassembled by simple operations, has good endurance with respect to severe vibrations and can reduce the damage of the machine body due to the adequate impact absorption ability even when the rammer tumbles. Front end sections of guard covers disposed on both sides of a power engine are joined and fixed to the front surface section of the crank chamber, lower sections of the rear portions are supported by support frames of a protective stand provided at the lower surface of the power engine, and the rear sections of the rear portions are linked integrally by a linking transverse pole.

Abstract: An engine stop switch and a fuel open-close lock are accommodated in a throttle lever case so that they can be easily disassembled, and the engine stop switch is turned on and off and the fuel open-close cock is opened and closed adequately by the actuation of a rotary valve in response to the turning of a lever. An engine stop switch and a fuel open-close lock are integrally incorporated in a throttle lever case, a partially toothless driven gear is intermittently rotated via a partially toothless drive gear 4 rotated by a lever 6, and the intermittent rotation of the partially toothless driven gear turns on/off the engine stop switch and opens/closes the fuel open/close cock.

Abstract: In a vibration compaction machine such as a rammer, a lining wear dust is prevented from accumulating inside a clutch drum due to oblique attachment of a centrifugal clutch, such that the input shaft side is high and the output shaft side is low because of a forward tilted posture of the machine body. Discharge ports for a lining wear dust are opened with a spacing therebetween in a corner section of a disk-shaped wall surface and an annular circumferential surface of a clutch drum in a centrifugal clutch that is disposed obliquely so that the input shaft is high and an output shaft is low, the discharge ports being obtained by cutting out portions of the annular circumferential surface close to the corner section.