| 摘要 |
<p>A 4-wheel tractor having brakes (28, 30) on the rear wheels (20, 22) only and a FWD clutch (44) for selectively drivingly coupling the front wheels (66, 68) to the rear wheels (20, 22), is provided with a control circuit (80, 82), operative during rear wheel braking, for controlling the clutch (44) so that the front wheels (66, 68) are intermittently coupled to and uncoupled from the rear wheels (20, 22). Brake pedals (32, 36) which individually control the rear wheel brakes (28, 30), and a hand brake (87) all control switches connected to a controller. A FWD switch (88) is also connected to the controller. A ground speed sensor (92) applies to the controller a signal representing the speed of the tractor. If the tractor speed is above 15mph at the time both brake pedals (32, 36) are depressed, the controller selectively controls a solenoid (54) so that the clutch (44) is selectively engaged and disengaged in a first sequence if the FWD switch (88) is ON but selectively controls the solenoid (54) so that the clutch is selectively engaged and disengaged in a second sequence if the FWD switch (88) is in an OFF or an AUTO position. Operation of the clutch (44) effects intermittent front wheel braking as the rear wheels (20, 22) are braked so that front wheel skidding is reduced during hard braking. <IMAGE></p> |
