Vehicle driving mechanism having a synchromesh gearbox with an additional clutch in each of two power branches

A mechanism for driving motor vehicles comprising:

• a synchromesh gearbox, with fixed gears, idler gears and synchronized shift clutches forming two power branches;
• each power branch has on a first shaft at least two fixed gears and on a second shaft at least two idler gears and at least two synchronized shift clutches;
• each power branch contains one wet friction clutch and at least two non-consecutive speeds;
• in each speed, power flows via a gear set formed by a fixed gear and an idler gear, via a synchronized shift clutch and a friction clutch;
• said friction clutch is a disc clutch with inner discs and outer discs;
• a cooling oil flows from a bore in one shaft and cools said inner and outer discs;
• a switch piston and a cylinder housing form actuation means having an annular chamber;
• fluid pressure in said chamber pushes said switch piston axially against said inner discs and said outer discs and engages said friction clutch;
• and
• return springs disengage said friction clutch;
• the improvement comprising:
• said switch piston (39 or 139), with an axial extension (48 or 148), forms a sliding sleeve of a piston valve (3, 48, or 3, 148) for controlling the flow of the cooling oil to the inner discs (12 or 112) and outer discs (8 or 108);
• said switch piston (39 or 139) shuts off the cooling oil flow when said friction clutch (2 or 102) is disengaged or almost completely disengaged and supplies cooling oil flow almost immediately after said switch piston (39 or 139) begins to engage said friction clutch (2 or 102) and, upon engagement, a large amount of cooling oil flows through radial grooves in said inner discs (12 or 112);
• an inner disc carrier (9 or 109) for said inner discs (12 or 112) is situated axially, for common rotation, between said cylinder housing (35) having a radial annular chamber (56 or 156) and a compensating cylinder (14 or 114) having a compensating piston (17 or 117);
• a compression spring (20 or 120), axially situated between said inner disc carrier (9 or 109) and said switch piston (39 or 139) forms a weak return spring and a prestressed cup spring (19 or 119) axially situated between said compensating cylinder (14 or 114) and said compensating piston (17 or 117), forms a strong return spring for disengaging said friction clutch (2 or 102);
• pins (23 or 123) in bores (24 or 124) of said inner disc carrier (9 or 109), situated axially between said compensating piston (17 or 117) and said switch piston (39 or 139), transmit axial force to and from said compensating piston (17 or 117) and said switch piston (39 or 139);
• said pins (23 or 123) being active only during the beginning of disengagement and during the end of engagement of said friction clutch (2 or 102);
• wherein said friction clutch (2 or 102) also serves to start up the motor vehicle and said return springs having a maximum force of 5% to 20% of a maximum force of said switch piston (39 or 139).