Clutch actuating device

A hydraulic clutch actuating device operable via a clutch lever, comprising:

• a master cylinder having an output of hydraulic fluid at a first fluid pressure when the clutch lever is pulled;
• an actuating cylinder having a piston, rod-side chamber, and a clutch actuation chamber, the rod-side chamber being in fluid connection with the output of the master cylinder;
• a passage interconnecting the rod-side chamber with the clutch actuation chamber of the actuating cylinder, a check-valve being located in the passage;
• a slave cylinder in fluid connection with the clutch actuation chamber of the actuating cylinder;
• a multiplier cylinder having a piston-side chamber and a rod-side chamber separated by a piston;
• a rod or a series of interconnecting rods extending from the piston of the multiplier cylinder through the rod-side chamber of the multiplier cylinder to the piston of the actuating cylinder through the rod-side chamber of the actuating cylinder;
• a secondary pressure source;
• and
• a directional control valve including a pilot port in fluid connection with the output of the master cylinder, a port in fluid connection with the piston-side chamber of the multiplier cylinder, and a port in fluid connection with the secondary pressure source;
• and
• wherein, when the first fluid pressure (P1) from the master cylinder is simultaneously applied to the pilot port of the directional control valve and the 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 pressure source via the directional control valve, such that the second fluid pressure (P2) transmitted by the rod or series of rods and the first fluid pressure (P1) jointly act on the piston of the actuating cylinder to produce a clutch actuation fluid pressure that is applied to the slave cylinder.