Abstract: A hydraulic control system for a transmission is provided with a power source, two drive wheels, a power transmission device, a hydraulic pump, a main valve, and a controller. The power transmission device is configured to be set to a plurality of speed stages. The main valve is disposed between the hydraulic pump and the power transmission device and adjusts the main pressure of hydraulic fluid supplied from the hydraulic pump to the power transmission device. The controller controls the main valve. The controller sets the main pressure to a pressure value derived by correcting a clutch holding pressure of the set speed stage based on a load applied to each of the drive wheels.

Abstract: A hydraulic circuit includes a hydraulic pump configured to supply lubricating oil, a resisting apparatus configured to maintain an oil pressure of the lubricating oil supplied from the hydraulic pump, an oil supply channel configured to guide the lubricating oil from the hydraulic pump to the resisting apparatus, and an optical detector configured to measure a degree of contamination of the lubricating oil flowing through the oil supply channel.

Abstract: A first carrier rotates integrally with an input shaft. A third sun gear and a fourth sun gear rotate integrally with a first intermediate shaft. A third carrier rotates integrally with a second ring gear. A fourth carrier rotates integrally with a third ring gear, and outputs power. A first clutch couples a first ring gear and a second sun gear to the first intermediate shaft. A second clutch couples the first carrier to a second carrier. A third clutch couples the second carrier to the first intermediate shaft. A first brake brakes rotation of a first sun gear. A second brake brakes rotation of the second ring gear and the third carrier. A third brake brakes rotation of a fourth ring gear.

Abstract: A first carrier rotates integrally with an input shaft. A third sun gear and a fourth sun gear rotate integrally with a first intermediate shaft. A third carrier rotates integrally with a second ring gear. A fourth carrier rotates integrally with a third ring gear, and outputs power. A first clutch couples a first ring gear and a second sun gear to the first intermediate shaft. A second clutch couples the first carrier to a second carrier. A third clutch couples the second carrier to the first intermediate shaft. A first brake brakes rotation of a first sun gear. A second brake brakes rotation of the second ring gear and the third carrier. A third brake brakes rotation of a fourth ring gear.

Abstract: A planetary gear type gearbox includes a front-stage transmission section and rear-stage transmission section. The front-stage transmission section is for transmitting power from an input shaft to an intermediate shaft. The front-stage transmission section includes first, second and third clutches, two sets of planetary gear trains axially adjoining to each other. The first planetary gear train includes a sun gear, a carrier, a ring gear and planet gears. The second planetary gear train includes a sun gear, a carrier, a ring gear and two sets of planet gears. In the activation of second and third clutches, power is inputted into the carrier from the input shaft and is then outputted from the ring gear of the first planetary gear train.

Abstract: In a motor grader, when a cylinder hydraulic pressure detected by a cylinder-hydraulic-pressure-detecting section is less than a predetermined threshold value, a control section makes a determination that the motor grader is in a running state and uses a running-hydraulic-pressure waveform corresponding to the running state to control the hydraulic pressure supplied to a clutch. When the cylinder hydraulic pressure is greater than or equal to the threshold value, the control section makes a determination that the motor grader is in a working state and uses a working-hydraulic-pressure waveform corresponding to the working state to control the hydraulic pressure supplied to the clutch.

Abstract: A planetary gear type gearbox includes a front-stage transmission section and rear-stage transmission section. The front-stage transmission section is for transmitting power from an input shaft to an intermediate shaft. The front-stage transmission section includes first, second and third clutches, two sets of planetary gear trains axially adjoining to each other. The first planetary gear train includes a sun gear, a carrier, a ring gear and planet gears. The second planetary gear train includes a sun gear, a carrier, a ring gear and two sets of planet gears. In the activation of second and third clutches, power is inputted into the carrier from the input shaft and is then outputted from the ring gear of the first planetary gear train.

Abstract: In a motor grader, when a cylinder hydraulic pressure detected by a cylinder-hydraulic-pressure-detecting section is less than a predetermined threshold value, a control section makes a determination that the motor grader is in a running state and uses a running-hydraulic-pressure waveform corresponding to the running state to control the hydraulic pressure supplied to a clutch. When the cylinder hydraulic pressure is greater than or equal to the threshold value, the control section makes a determination that the motor grader is in a working state and uses a working-hydraulic-pressure waveform corresponding to the working state to control the hydraulic pressure supplied to the clutch.

Abstract: To provide a transmission capable of: reducing horsepower loss by reducing the amount of lubricating oil for a power transmission system including speed gears when the present speed gear is a specified gear of the speed gears; and securing the lubricating oil amount for the transmission system during a shift performed when the present gear is the specified speed gear. The transmission includes: the power transmission system; a lubricating oil amount reducing mechanism for reducing the lubricating oil amount supplied to the power transmission system when the present gear is the specified speed gear; and controller for determining a shift point vehicle speed pertaining to the specified speed gear based on a preset shift map, and activating the oil amount reducing mechanism, when a difference between the shift point vehicle speed and actual vehicle speed exceeds a first predetermined value and while the specified speed gear is the present gear.

Abstract: To provide a transmission capable of: reducing horsepower loss by reducing the amount of lubricating oil for a power transmission system including speed gears when the present speed gear is a specified gear of the speed gears; and securing the lubricating oil amount for the transmission system during a shift performed when the present gear is the specified speed gear. The transmission includes: the power transmission system; a lubricating oil amount reducing mechanism for reducing the lubricating oil amount supplied to the power transmission system when the present gear is the specified speed gear; and controller for determining a shift point vehicle speed pertaining to the specified speed gear based on a preset shift map, and activating the oil amount reducing mechanism, when a difference between the shift point vehicle speed and actual vehicle speed exceeds a first predetermined value and while the specified speed gear is the present gear.

Abstract: A fluid pressure control valve apparatus for a clutch or a brake which is small in size and capable of reducing occurrence of malfunction of a pressure control valve caused by dust caught therein is provided. For this purpose, a fluid pressure control valve apparatus (2) for controlling a pressure of a fluid and feeding it to a clutch or a brake includes a pressure control valve (30) for controlling fluid pressure, an electromagnetic proportional pilot operated valve (50) for issuing an operation command for the pressure control valve with pilot pressure according to a command current to a proportional solenoid (40), and a flow detecting valve (10) for detecting a flow of the fluid to be fed to the clutch or the brake from the pressure control valve to detect completion of filling in the clutch or the brake.

Abstract: A fluid pressure control valve apparatus for a clutch or a brake which is small in size and capable of reducing occurrence of malfunction of a pressure control valve caused by dust caught therein is provided. For this purpose, a fluid pressure control valve apparatus (2) for controlling a pressure of a fluid and feeding it to a clutch or a brake includes a pressure control valve (30) for controlling fluid pressure, an electromagnetic proportional pilot operated valve (50) for issuing an operation command for the pressure control valve with pilot pressure according to a command current to a proportional solenoid (40), and a flow detecting valve (10) for detecting a flow of the fluid to be fed to the clutch or the brake from the pressure control valve to detect completion of filling in the clutch or the brake.