Abstract

A hydraulic actuation unit, particularly for controlling the starting and stopping of hydraulic motors, comprising: - a first main circuit (2) and a second main circuit (3), which are adapted to connect selectively a supply of pressurized working liquid and a tank to a hydraulic motor (100); - a first recirculation circuit (4) and a second recirculation circuit (5) for returning respectively a fraction of the working liquid from the second main circuit (3) to the first main circuit (2) and vice versa; - a counterbalancing valve (6), which comprises a shuttle (7) that can switch to a first end position (PI) and to a second end position (P2), which correspond to the actuation of the motor (100) with mutually opposite directions of rotation, and comprises a first passage channel (8) and a second passage channel (9), which are arranged respectively along the first main circuit (2) and along the second main circuit (3); - a first discharge channel (10) and a second discharge channel (11), for the connection respectively of the first main circuit (2) to the second recirculation circuit (5) and of the second main circuit (3) to the first recirculation circuit (4). The shuttle (7) comprises a first check valve (50) and a second check valve (70) respectively arranged in the first passage channel (8) and in the second passage channel (9). The first check valve (50) comprising at least one first flow control element (51) that can move from an open position, for the passage of the working liquid along the first passage channel (8) and therefore along the first main circuit (2), to a closure position, for closing the first passage channel (8) and therefore the first main circuit (2) and vice versa. The second check valve (70) comprises at least one second flow control element (71) that can move from an open position for the passage of the working liquid along the second passage channel (9) and therefore along the second main circuit (3) to a closure position for the closure of the second passage channel (9) and therefore of the second main circuit (3) and vice versa. The peculiarity of the invention resides in that the first check valve (50) and the second check valve (70) respectively are provided with first damping means (52) and second damping means (72) in order to slow down the passage movement respectively of the first flow control element (51) and of the second flow control element (71) from the respective closure position to the respective open position.

IPC Classes  ?

• F03C 1/04 - Reciprocating-piston liquid engines with multiple cylinders, characterised by the number or arrangement of cylinders with cylinders in star- or fan-arrangement