초록 ▼

Clutch-clutch-brake steering unit having hydraulically actuated cylinders for controlling same to control rotation of a track-drive sprocket in a crawler tractor. Specifically, one of the clutch cylinders and a brake cylinder provided in the unit have an inlet-outlet port in common, and are so arran

Clutch-clutch-brake steering unit having hydraulically actuated cylinders for controlling same to control rotation of a track-drive sprocket in a crawler tractor. Specifically, one of the clutch cylinders and a brake cylinder provided in the unit have an inlet-outlet port in common, and are so arranged on a spring-applied-brake, hydraulically-applied-clutch basis that a single pressure signal in the inlet-outlet port alternately operates the cylinders to apply the brake and release the one clutch, to apply the one clutch and release the brake or, by proper modulation, to partially engage either, i.e., slip the clutch or drag the brake to intermediate degrees as desired. And, to nearly the same extent, the other clutch cylinder and the brake cylinder provided in the unit have inlet-outlet ports in common and are similarly arranged that the absence or presence of a single pressure control signal in their inlet-outlet ports alternately operates the cylinders to apply the brake and release the other clutch, or to apply the other clutch and release the brake.

대표청구항 ▼

Transmission mechanism comprising a multi-ratio drive and braking train (38,38-2) having devices comprising at least one spring applied braking device and two drive devices, each drive device hydraulically disposed so as to be separately hydraulically paired with the braking device, a modulator valv

Transmission mechanism comprising a multi-ratio drive and braking train (38,38-2) having devices comprising at least one spring applied braking device and two drive devices, each drive device hydraulically disposed so as to be separately hydraulically paired with the braking device, a modulator valve (44-2) for modulating the output supplied by an operating fluid pressure source of operating fluid under pressure, having restricted common pressure ports (174, 200-2) common to the braking device and to different ones of those drive devices each of which is separately paired with the braking device, said modulator valve operable to selectively connect said operating fluid pressure source alternately to each such common pressure port; plural springs comprising one plurality of springs of one strength operative in the braking device (90B-2) for brake application and operatively overcome by the force of the operating fluid pressure for braking pressure neutralization and, thereupon, for filling the braking device and causing the springs to yield for complete brake release; and another plurality of the springs of one strength operative in the drive devices (96C-2, 97H-2) for drive disengagement and operatively overcome by the force of the operating fluid pressure for filling the drive devices and causing the springs of the latter to yield for initiating drive engagement; there being stronger springs in the spring-applied braking device (90B-2) than in each fluid-engaged drive device paired therewith so that filling of each of the latter (96C-2, 97H-2) and initiation of its engagement always precedes filling of the paired braking device through their respective port common therewith, thus inherently affording a cushioned drive engagement once initiated, due to the delay time required for fluid to flow through such common port.