Friction coupling control system

In a vehicle (10) having a brake control system (8), a brake (18) movable between engaged and disengaged positions, a seat (44,46), and an electrical switch (28) movable between first (27) and second (29) positions in response to a load being removed from and being placed on said seat, the improvement comprising:

• a linkage assembly (62) having first (64) and second (66) over center positions and being connected to said brake (18) and said vehicle (10), said linkage assembly (62) being movable between a first over center position (64) at which said brake is engaged (15) and a second over center position (66) at which said brake is disengaged (17);
• first and second electrical circuits (38,42) and first and second solenoids (48,50), each connected in a respective electrical circuit (38,42), said first and second electrical circuits (38,42) each being connected to said seat responsive electrical switch (28) and to a respective one of said first and second solenoids (48,50);
• said first and second solenoids (48,50) being connected to said vehicle (10) at spaced apart positions and on opposite sides of said linkage assembly (62);
• said first solenoid (48) being actuated in response to said seat responsive switch (28) being in one of said first and second positions (27,29) and the other of said solenoids (50) being actuated in response to the seat responsive switch (28) being in the other of said first and second positions (27,29), said solenoids being of a construction sufficient for moving said linkage assembly (62) between said first and second over center positions (64,66);
• and
• means (70) for deactivating one of said first and second solenoids (48,50) in response to said linkage assembly (62) being at one of said first (64) and second (66) over center positions.

In a lift truck (10) having a parking brake control system (8), a friction parking brake (18) moveable between a brake engaged (15) and disengaged (17) position, a seat (44), and an electrical switch (28) moveable between a first and second position (27,29) in response to deflection of said seat (44), the improvement comprising:

• a linkage assembly (62) having a first (64) and second (66) over center position and being connected to said brake (18) and said vehicle (10), said linkage assembly (62) being moveable between a first position (64) at which said brake is engaged (15) and a second position (66) at which said brake is disengaged (17);
• said linkage assembly (62) being of a construction sufficient for maintaining said brake (18) at the engaged position (15) at the first over center position (64) and for maintaining said brake at the disengaged position (17) at the second over center position (66);
• a first electrical circuit (38) having a first solenoid (48) and being connected to said first solenoid (48) and said switch (28), said first solenoid (48) being actuatable in response to said switch (28) being at said first position (27) and said first solenoid (48) being engageable with said linkage assembly (62) and being of a construction sufficient for moving said linkage assembly (62) to the first position (64);
• a second electrical current (42) having a second solenoid (50) and being connected to said second solenoid (50) and said switch (28), said second solenoid (50) being actuatable in response to said switch (28) being at said second position (29) and said second solenoid (50) engageable with said linkage assembly (62) and being of a construction sufficient for moving said linkage assembly (62) to said second position (66);
• and
• a switch assembly (72) connected to said first (28) and second circuits (42) and actuatable by said linkage assembly (62) at said first (64) and second positions (66) of said linkage assembly (62), said switch being of a construction sufficient for deactivating said first and second solenoids (48,50).

A friction coupling control system (8) having a frame (12), a friction coupling (18) mounted on said frame (12) and being movable between an engaged (15) and disengaged (17) position, comprising:

• a linkage assembly (62) having first (64) and second (66) over center positions and being connected to said friction coupling (18) and said frame (12), said linkage assembly (62) being movable between a first over center position (64) at which said friction coupling (18) is maintained at the engaged position (15) and a second over center position (66) at which said friction coupling (18) is maintained at the disengaged position (17);
• an electrical switch (28) having a first and second position (27,29) and being movable between said first and second positions (27,29);
• first and second electrical circuits (38,42) and first and second solenoids (48,50), said first electrical circuit (38) being connected to said first solenoid (48) and said electrical switch (28) and said second electrical circuit (42) being connected to said second solenoid (50) and said electrical switch (28), said first solenoid (48) being actuatable in response to said electrical switch (28) being at one of said first and second positions (27,29) to move said linkage assembly (62) to one of said first and second over center positions (64,66) and said second solenoid (50) being actuatable in response to said electrical switch (28) being at the other of said first and second positions (29,27) to move said linkage assembly (62) to the other of said first and second over center positions (64,66);
• and
• means (70) for deactivating one of said first and second solenoids (48,50) in response to actution of said deactivating means by said linkage assembly (62) at one of said first (64) and second (66) over center positions of said linkage assembly and for deactivating the other of said first and second solenoids (50,48) in response to actuation of said deactivating means by said linkage assembly (62) at the other of said first (64) and second (66) over center positions of said linkage assembly.