| 摘要 |
<p>899,739. Controlling clutches; clutch-brake combinations. CATERPILLAR TRACTOR CO. July 25, 1960 [Aug. 26, 1959], No. 25773/60. Class 80 (2). [Also in Groups XXXI and XXXIV] In a vehicle having a fluid-actuated transmission clutch and fluid-actuated brakes, means are provided for automatically releasing the clutch upon operation of the brakes and to delay release of the clutch until the brakes are fully applied. The brake system comprises a master cylinder 12 supplying the wheel cylinders 15 through a line 14, the piston 13 of the master cylinder being operated by fluid pressure acting on a piston 16 and being received from a'supply 20 through lines 21 and 22 controlled by a valve 23 normally held closed by a spring 24. A closed hydraulic circuit comprising a piston 29, cylinder 30, line 31 and a piston 32 is provided for actuating the valve 23 from the brake pedal 26. The transmission 35 comprises one or more hydraulically operated clutches normally held in the closed position and receiving pressure fluid from a pump 36 through a line 39 provided with a conventional control valve 38 for normal operation. A valve 42 normally held open by a spring 41 is provided in the line 39 and may be closed by a piston 49, the line 39 then being opened to reservoir so as to disengage the clutch or clutches, the piston 49 being operated by air pressure through a line 52 under the control of a valve 53 connected by an adjustable screw 54 to a brake pedal 46 normally held by a spring 47 in a position whereby the valve 53 is closed. An arm 56 extends from the pedal 26 to beneath the pedal 46. Upon depressing pedal 26, the brakes are applied. Upon depressing pedal 46, the clutch(es) are disengaged and additionally the brakes are applied through arm 56. A check valve 58 is provided in the brake-actuating line 22, offering little resistance to the application of the brakes but retarding their release, the return fluid having to pass through a small orifice 59. Upon release of the pedal 46, the check valve ensures that the transmission is engaged before complete release of the brakes, and upon depressing the pedal 46, the spring 41 retards the operation of the valve 42 to an extent which enables the brakes to be applied before the clutch(es) are disengaged. The air escaping from the brake line 22 is vented to atmosphere through a line 60. A line 61 is also provided to avoid locking the piston 16.</p> |
