Vibration exciter for construction machines

A vibration exciter for a construction machine comprising:

• (a) at least one axis having at least first and second imbalance masses;
• and
• (b) a pivot motor for adjustment of a rotational position of at least one of the first and second imbalance masses;
• wherein the pivot motor comprises a pivot motor shaft comprising an axial bore, a pivot motor housing mounted to rotate on the pivot motor shaft, a lance disposed in torque-proof manner projecting into the axial bore, said lance comprising at least first and second channels for supplying hydraulic oil to the pivot motor, said first and second channels ending in first and second ring grooves on an outside portion of the lance, at least in certain regions, at a distance from one another, and at least first and second pressure chambers for receiving the hydraulic oil for driving the pivot motor;
• wherein the pivot motor shaft comprises radial bores for connecting the first and second ring grooves with the first and second pressure chambers;
• and
• wherein a fit between the lance and the axial bore of the pivot motor shaft is structured as a tight slide bearing near the first and second ring grooves.