Provided in a tamping unit for tamping a track are squeezing drives (14) for a squeezing motion of tamping tines. In a hydraulic cylinder (19)having a squeezing piston (17) with a piston rod (18)of the squeezing drive (14), a first pressure chamber (20) for producing the squeezing motion (8) is provided. Additionally arranged is a second pressure chamber (21) for producing an opening motion directed opposite to the squeezing motion, and a third pressure chamber (22) provided for producing vibrations.

A hydraulic vibration generation device or hydraulic motor is provided. The device includes a manifold having an inner volume with a pressure chamber extending into the inner volume, a fluid inlet orifice and a fluid outlet orifice. The device further includes a vibration generating member having a grooved drive and an off-center weight and retaining plates. The inner volume receives the vibration generating member within the inner volume. The vibration generating member rotates and generates vibration in response to hydraulic fluid flowing into the manifold through the inlet orifice and directed through the pressure chamber, relieves pressure upon exiting the pressure chamber and out of the manifold through the outlet orifice. Also provided a hydraulic motor with a same manifold and pressure chamber, but with a power generating member having the same groove drive without and off-center weight. Rotation of the power generating member generates power.

A vibration system for a compactor drum including a central support structure fixedly mounted within the compactor drum. The vibration system also includes a first vibratory exciter coupled to the central support structure. The vibration system further includes a second vibratory exciter coupled to the central support structure. The second vibratory exciter is longitudinally spaced apart from the first vibratory exciter. The vibration system includes a stabilizer element coupled to, and extending between, the first and second vibratory exciters. The stabilizer element is parallel to the central support structure.

A vibration exciter with load compensation for the dynamic excitation of test specimens includes a base, an actuator, an armature which can be moved by the actuator in an excitation direction relative to the base and guided by a linear guiding element parallel to the excitation direction, and a pneumatic load compensator which compensates for the gravity force of at least the armature and the test specimen being excited. A high-quality low-perturbation exciter signal is generated by minimizing friction and other nonlinearities occurring during the load compensation. The linear guiding element of the vibration exciter with load compensation includes an air bearing, and the load compensator includes the linear guiding element.

A vibration exciter with load compensation for the dynamic excitation of test specimens includes a base, an actuator, an armature which can be moved by the actuator in an excitation direction relative to the base and guided by a linear guiding element parallel to the excitation direction, and a pneumatic load compensator which compensates for the gravity force of at least the armature and the test specimen being excited. A high-quality low-perturbation exciter signal is generated by minimizing friction and other nonlinearities occurring during the load compensation. The linear guiding element of the vibration exciter with load compensation includes an air bearing, and the load compensator includes the linear guiding element.

A tamping machine, particularly for regenerating railway ballasts, includes: a supporting frame, a vibrating tamping hammer pivoted to the frame, and a hydraulic actuator engaged with a thrusting portion of the tamping hammer. The actuator includes first and second axially aligned sections engaged with each other, one of which is engaged with the thrusting portion of the tamping hammer and the other section is engaged with an abutment portion. The first section is extendable while the second section is supplied by distributing means having an alternate cyclical operation for enabling the tamping hammer to vibrate. The second section is a jacket extending between a first and second longitudinal ends, and a piston slidingly movable inside the jacket. The jacket is closed at the first and second longitudinal ends; the piston exhibits an overall axial size defined by respective thrusting opposite faces of the piston itself, which is entirely contained inside the jacket.

A tamping machine, particularly for regenerating railway ballasts, includes: a supporting frame, a vibrating tamping hammer pivoted to the frame, and a hydraulic actuator engaged with a thrusting portion of the tamping hammer. The actuator includes first and second axially aligned sections engaged with each other, one of which is engaged with the thrusting portion of the tamping hammer and the other section is engaged with an abutment portion. The first section is extendable while the second section is supplied by distributing means having an alternate cyclical operation for enabling the tamping hammer to vibrate. The second section is a jacket extending between a first and second longitudinal ends, and a piston slidingly movable inside the jacket. The jacket is closed at the first and second longitudinal ends; the piston exhibits an overall axial size defined by respective thrusting opposite faces of the piston itself, which is entirely contained inside the jacket.

An apparatus is provided for compacting the ballast bed of a track, comprising a machine frame which is movable on the track with a stabiliser unit which runs on rollers on the track and is equipped with a vibration drive for producing a vibration in a plane parallel to the track. The stabiliser unit is preferably equipped with tension rollers engaging around the rail head. The stabiliser unit is linked in a height-adjustable manner to the machine frame with an adjusting drive and can be moved against the track under load. In order to provide advantageous constructional conditions it is provided that the vibration drive comprises at least one cylinder vibrator which is formed by a hydraulic cylinder and is triggered via a proportional or servo valve.

A method for adjusting the position of an eccentric mass from the axis of rotation of a mechanism comprises rotating an eccentric mass about an axis of rotation, and moving the eccentric mass closer or further away from the axis of rotation solely by the changing the speed of rotation of the eccentric mass about the axis of rotation.

An ultrasonic probe and an ultrasonic detecting device provided with the ultrasonic probe. The ultrasonic probe includes: an ultrasonic transducer array configured to transmit and receive ultrasonic waves; a conducting device disposed at the front end of the ultrasonic transducer array, and the conducting device includes a fluid chamber filled with fluid. The fluid chamber has an opening and an energy receiving port which are in communication with each other, and the opening is disposed on a front surface of the conducting device and covered by an elastic film; an energy applying device, connected to the energy receiving port to apply energy to the fluid within the fluid chamber to make the elastic film vibrate so as to generate a shear wave.