A pressure compensator, particularly for oleodynamic applications, comprising two cylinders: a compensator cylinder in which is slidingly engaged a first piston comprising a first piston rod, and a reducing cylinder, in which is slidingly engaged a second piston comprising a second piston rod axially connected to the first piston rod; said compensator cylinder being coupled to a main oleodynamic cylinder; said compensator cylinder having a size so designed as to provide the same area ratio as that of the main cylinder, thereby to a set position of said main cylinder piston corresponding a precise position of the first piston of the compensator cylinder; said reducing cylinder comprising at least a low-pressure chamber coupled to a pressure gauge; a displacement of the reducing cylinder piston rod either increases or decreases a pressure in said low-pressure chamber, proportionately to a working pressure in the main cylinder.

A clutch actuating device has an actuating cylinder with piston and rod-side chamber, a multiplier cylinder with piston-side and rod-side chambers separated by a piston, a rod(s) interconnecting the pistons, and a directional control valve. The valve has a pilot port, ports in fluid connection with piston-side and rod-side chambers of the multiplier cylinder, and a port in fluid connection with a secondary source. When a first fluid pressure (P1) from a first pressure source is applied to the pilot port and rod-side chamber of the actuating cylinder, a second fluid pressure (P2) is applied to the piston-side chamber of the multiplier cylinder by the secondary source. This results in the first and second fluid pressures (P1 and P2) acting on the piston of the actuating cylinder to produce a clutch actuation fluid pressure.

A clutch actuating device has an actuating cylinder with piston and rod-side chamber, a multiplier cylinder with piston-side and rod-side chambers separated by a piston, a rod(s) interconnecting the pistons, and a directional control valve. The valve has a pilot port, ports in fluid connection with piston-side and rod-side chambers of the multiplier cylinder, and a port in fluid connection with a secondary source. When a first fluid pressure (P1) from a first pressure source is applied to the pilot port and rod-side chamber of the actuating cylinder, a second fluid pressure (P2) is applied to the piston-side chamber of the multiplier cylinder by the secondary source. This results in the first and second fluid pressures (P1 and P2) acting on the piston of the actuating cylinder to produce a clutch actuation fluid pressure.

A clutch actuating device has an actuating cylinder with piston and rod-side chamber, a multiplier cylinder with piston-side and rod-side chambers separated by a piston, a rod(s) interconnecting the pistons, and a directional control valve. The valve has a pilot port, ports in fluid connection with piston-side and rod-side chambers of the multiplier cylinder, and a port in fluid connection with a secondary source. When a first fluid pressure (P1) from a first pressure source is applied to the pilot port and rod-side chamber of the actuating cylinder, a second fluid pressure (P2) is applied to the piston-side chamber of the multiplier cylinder by the secondary source. This results in the first and second fluid pressures (P1 and P2) acting on the piston of the actuating cylinder to produce a clutch actuation fluid pressure.

A hydraulic system includes: a first bi-directional pump connected to a head-side chamber of a single-rod cylinder by a head-side line and connected to a rod-side chamber of the single-rod cylinder by a rod-side line; and a second bi-directional pump connected to the head-side line by a supply/discharge line, the second bi-directional pump being a variable displacement pump. The hydraulic system further includes a low-pressure selection valve connected to the head-side line by a first discharge line and connected to the rod-side line by a second discharge line, wherein the low-pressure selection valve allows the second discharge line or the first discharge line to communicate with a relief line on which a relief valve is located.