Abstract: A percussion tool has a cooling air channel for guiding a cooling air flow from a cooling air fan to an outside wall of a cylinder of an internal combustion engine. The cooling air channel is tapered to the extent that partial cooling air flows guided between the respective cooling fins are branched off the main cooling air flow. In such a way, the flow rate of the cooling air flow in the cooling air channel remains substantially constant, resulting in optimized engine cooling. The cooling air channel may be divided into two cooling air channels downstream of the cylinder. One of the cooling air channels guides cooling air to an exhaust gas system of the internal combustion engine, while the other cooling air channel guides cooling air to an outside wall of the guide housing of a hammer mechanism.

Abstract: A vibrating plate for compacting soil comprises an upper mass; a lower mass, which is elastically coupled to the upper mass and which has at least one soil contact plate, and; a vibration generator device that acts upon the soil contact plate. The vibration generator device comprises at least four unbalanced masses that can each be rotationally driven about a rotation axis, the rotation axis of at least two of the unbalanced masses being arranged at an angle to the rotation axes of the other unbalanced masses. One of the unbalanced masses depicts a reference unbalanced mass that does not require its own phase adjusting device. On the other hand, a separate phase adjusting device is assigned to each of the other unbalanced masses, enabling the phase position of these unbalanced masses to be individually adjusted with regard to the reference unbalanced mass.

Abstract: A vibrating plate comprises a vibration generator device, which can be controlled in such a manner that the direction of the action of force can be set at a number of locations, particularly in more than two locations. In addition, an advance adjusting device is provided for controlling the vibration generator device whereby the direction of the action of force is set in a position in which a maximum possible advance of the vibrating plate is reached. The direction of the action of force can be changed according to a change in the surroundings of the vibrating plate, particularly to the slope and/or the hardness of a subsoil to be compacted by a soil contact plate. Alternatively, the direction of the action of force can be changed according to the wishes of the operator.

Abstract: A percussive mechanism, which is provided in the form of an, e.g. pneumatic spring percussive mechanism, comprises an electrodynamic linear drive, a drive piston, which can be reciprocally moved inside a percussive mechanism housing by the linear drive, and a percussive piston. An additional hollow space is provided in front of and/or behind the drive piston and can be isolated at least in part from the surrounding area so that a pneumatic spring can be created in the additional hollow space. The pneumatic spring slows the drive piston at its returning points and facilitates a returning motion without loading the electrodynamic linear drive.

Abstract: A percussion tool has a cooling air channel for guiding a cooling air flow from a cooling air fan to an outside wall of a cylinder of an internal combustion engine. The cooling air channel is tapered to the extent that partial cooling air flows guided between the respective cooling fins are branched off the main cooling air flow. In such a way, the flow rate of the cooling air flow in the cooling air channel remains substantially constant, resulting in optimized engine cooling. The cooling air channel may be divided into two cooling air channels downstream of the cylinder. One of the cooling air channels guides cooling air to an exhaust gas system of the internal combustion engine, while the other cooling air channel guides cooling air to an outside wall of the guide housing of a hammer mechanism.

Abstract: A soil compaction device has a vibrated contact element that makes contact with the soil during a contact phase and that is exposed to a contact force exerted by the soil and travels over a contact distance. A dynamic stiffness of the soil is formed from the gradient of the contact force and from the contact distance. Furthermore, a contact surface parameter to take account of the actual contact surface of the contact element with the soil is determined. The dynamic deformation modulus is then the product of the contact surface parameter and the dynamic stiffness. The method allows the determination of the dynamic deformation modulus, and hence of the soil stiffness, during the compaction operation.

Abstract: A vibrating plate serving as a tamping device comprises an upper mass equipped with a drive and comprises at least two lower masses, which are coupled to the upper mass while being able to oscillate relative to the upper mass. Each of the lower masses comprises a soil contacting plate and at least one oscillator assigned to this soil contacting plate. The oscillators can be controlled differently so that, in addition to an advancing and compacting action, a turning moment can be executed about a vertical axis (Z).

Abstract: An implement has an internal combustion engine and a hydraulic system that can be driven by the internal combustion engine for bringing about a working movement. Furthermore, an energy accumulator is provided for the storage of energy in an accumulation phase in which the output delivered by the internal combustion engine is greater than the output currently required by the hydraulic system, and for the delivery of energy in a discharge phase in which the output delivered by the internal combustion engine is smaller than the output currently required by the hydraulic system. The energy accumulator thus serves for balancing output peaks and valleys such that the internal combustion engine may always be operated within an optimum range of rotational speeds.

Abstract: A vibrating plate comprises a vibration generator device, which can be controlled in such a manner that the direction of the action of force can be set at a number of locations, particularly in more than two locations. In addition, an advance adjusting device is provided for controlling the vibration generator device whereby the direction of the action of force is set in a position in which a maximum possible advance of the vibrating plate is reached. The direction of the action of force can be changed according to a change in the surroundings of the vibrating plate, particularly to the slope and/or the hardness of a subsoil to be compacted by a soil contact plate. Alternatively, the direction of the action of force can be changed according to the wishes of the operator.

Abstract: A vibration plate has an upper mass having a drive and a lower mass which is mounted so it is elastically moveable relative to the upper mass. The lower mass has a vibration generator and a ground contact plate. The drive is coupled by a belt drive to the vibration generator. The belt drive has a drive disk which is provided on the drive, an output disk which is provided on the vibration generator, and a belt which circulates between the drive disk and the output disk. To this end, at least two further deflection rollers are provided for guiding the belt.

Abstract: A vibrating plate serving as a tamping device comprises an upper mass (1) equipped with a drive and comprises at least two lower masses (2a, 2b), which are coupled to the upper mass (1) while being able to oscillate relative to the upper mass (1). Each of the lower masses (2a; 2b) comprises a soil contacting plate (6) and at least one oscillator (7) assigned to this soil contacting plate (6). The oscillators (7) can be controlled differently so that, in addition to an advancing and compacting action, a turning moment can be executed about a vertical axis (Z).

Abstract: A percussive mechanism, which is provided in the form of an, e.g. pneumatic spring percussive mechanism, comprises an electrodynamic linear drive, a drive piston, which can be reciprocally moved inside a percussive mechanism housing by the linear drive, and a percussive piston. An additional hollow space is provided in front of and/or behind the drive piston and can be isolated at least in part from the surrounding area so that a pneumatic spring can be created in the additional hollow space. The pneumatic spring slows the drive piston at its returning points and facilitates a returning motion without loading the electrodynamic linear drive.

Abstract: A vibrating plate for compacting soil comprises an upper mass; a lower mass, which is elastically coupled to the upper mass and which has at least one soil contact plate, and; a vibration generator device that acts upon the soil contact plate. The vibration generator device comprises at least four unbalanced masses that can each be rotationally driven about a rotation axis, the rotation axis of at least two of the unbalanced masses being arranged at an angle to the rotation axes of the other unbalanced masses. One of the unbalanced masses depicts a reference unbalanced mass that does not require its own phase adjusting device. On the other hand, a separate phase adjusting device is assigned to each of the other unbalanced masses, enabling the phase position of these unbalanced masses to be individually adjusted with regard to the reference unbalanced mass.

Abstract: The invention relates to an oil supply for an internal combustion engine, comprising an oil supply device for the supply of oil to a piston, reciprocating in a cylinder. The oil supply device is embodied such that at least at a point at which the piston is in the region of bottom dead centre, oil is introduced directly into a region below the piston, by means of the oil supply device, in particular, beneath the piston crown and within the piston skirt. The oil supply device thus comprises at least one tube element, extending into a region beneath the piston crown. The tube element terminates as close as possible to a gudgeon pin, when the piston is at bottom dead center. A targeted lubrication of the mechanically and thermally highly loaded gudgeon pin can thus be guaranteed. It is also possible by means of the oil supply to supply transfer ports of a two-stroke engine with oil, counteracting a tendency to coke up.

Abstract: A vibrating plate comprises an upper mass with a drive, a lower mass with a soil contact plate (12), and a vibration generator device, which belongs to the lower mass and which acts upon the soil contact plate (12). The vibration generator device comprises at least two individual exciters (13) each having an unbalanced shaft (2). The individual exciters (13) can be individually controlled with regard to the rotational speed and/or phase position of the respectively assigned unbalanced shaft (2). A mechanical coupling of the unbalanced shafts (2) is thus unnecessary. The unbalanced shaft (2) of an individual exciter (3) can be rotationally driven by a hydraulic motor (4). The position of the unbalanced shaft (2) is determined in at least one position by a position indicator (7).

Abstract: A vibrator for a ground compaction apparatus includes two parallel shafts which are coupled to one another be rotatable in opposite directions and on each of which is at least one unbalanced mass is disposed. A phase adjusting mechanism is used for modifying the phase angle of the two unbalanced masses relative to each other. In order to do so, the actual phase angle of the two unbalanced masses is detected with the help of proximity sensors or the like. A regulating device compares the actual phase angle with a desired phase angle that is predefined by the operator and controls the phase adjusting mechanism in such a way that the difference between the actual phase angle and the desired phase angle is minimal.

Abstract: A concrete finishing trowel comprising at least one rotor which is mounted on a frame and is provided with a rotatably driven shaft and several blades that are mounted on the driven shaft. A blade deflection mechanism moves the blades on a path that deviates from a circular path relative to the drive shaft.

Abstract: A soil compaction device has a vibrated contact element that makes contact with the soil during a contact phase and that is exposed to a contact force exerted by the soil and travels over a contact distance. A dynamic stiffness of the soil is formed from the gradient of the contact force and from the contact distance. Furthermore, a contact surface parameter to take account of the actual contact surface of the contact element with the soil is determined. The dynamic deformation modulus is then the product of the contact surface parameter and the dynamic stiffness. The method allows the determination of the dynamic deformation modulus, and hence of the soil stiffness, during the compaction operation.

Abstract: The invention relates to a hand-held working tool, having a first unit, powered by a vibration on operation and a second unit which may be displaced relative to the first unit. A vibration isolation device is arranged between the first and second unit, having an actuator, for generation of a control force. An operational force acting in the working direction (A) between the first and the second unit may be at least partly compensated by the control force. The actuator is pneumatically operated and comprises an air spring for vibration isolation. A working piston in an air spring percussion device on the working tool serves to supply compressed air for the air spring. Alternatively, the compressed air can be supplied by the oscillating relative movement between the first unit and the second unit.

Abstract: A boring and/or percussion hammer comprises an electrodynamic linear drive and a pneumatically damped percussion mechanism which is provided with a drive piston driven by the linear drive during the reciprocating movement thereof, an impact piston and a pneumatic spring arranged between the drive and impact pistons. An air-supply device comprises a pumping element, which is linearly forth and back movable for generating airflow. The pumping element is connected to the drive piston in such a way that the movement thereof is transmitted to said pumping element, thereby the cooling air is transported by an air channel for cooling heat generated elements.