Abstract: A controller is configured to acquire current terrain information indicating the current terrain in the travel direction of a work vehicle. the controller is configured to generate an inclined virtual surface extending form the current position of the work vehicle. The controller is configured to decide the soil volume of the current terrain located above the virtual surface. The controller is configured to set the virtual surface in which the soil volume of the current terrain becomes a predetermined target soil volume to be a virtual design surface. The controller is configured to generate a command signal to a work implement of the work vehicle to move the work implement along the virtual design surface.

Abstract: A work vehicle includes a vehicle body, a blade supported on the vehicle body, a pair of first hydraulic cylinders for moving the blade upward and downward, a pair of second hydraulic cylinders for tilting the blade forward, backward, leftward, and rightward, a pair of stroke sensors for detecting stroke amounts of the pair of first hydraulic cylinders, and a controller for controlling a position of the blade based on a difference in the stroke amounts of the pair of first hydraulic cylinders when, in a state where one second hydraulic cylinder is at the one stroke end or the other stroke end, the other second hydraulic cylinder is driven from one stroke end to the other stroke end.

Abstract: A work vehicle includes a vehicle body, a blade supported on the vehicle body, a pair of first hydraulic cylinders for moving the blade upward and downward, a pair of second hydraulic cylinders for tilting the blade forward, backward, leftward, and rightward, a pair of stroke sensors for detecting stroke amounts of the pair of first hydraulic cylinders, and a controller for controlling a position of the blade based on a difference in the stroke amounts of the pair of first hydraulic cylinders when, in a state where one second hydraulic cylinder is at the one stroke end or the other stroke end, the other second hydraulic cylinder is driven from one stroke end to the other stroke end.

Abstract: A bulldozer includes a blade pivotably attached to a vehicle body, a blade operation lever, and a blade control section. The blade operation lever outputs a lowering instruction signal, a holding instruction signal, and a raising instruction signal for the blade. The blade control section controls a height of the blade according the signal input. The blade control section can lower the blade to a predetermined position when the lowering instruction signal and the holding instruction signal are input in order after a transmission has been switched from a state, which is different from an advancing state, to the advancing state. The blade control section can raise the blade to a predetermined position when the raising instruction signal and the holding instruction signal are input in order after a transmission has been switched from a state, which is different from a reversing state, to the reversing state.

Abstract: A blade control system includes an angle obtaining part, an open ratio setting part and a lift cylinder controlling part. The angle obtaining part is configured to obtain an angle of a lift frame with respect to a designed surface. The open ratio setting part is configured to set an open ratio based on the angle. The lift cylinder controlling part is configured to open a proportional control valve at the open ratio for elevating the blade when a distance between the designed surface and an edge of a blade is determined to be less than or equal to a threshold.

Abstract: An engine output control system is for a work vehicle composed of an engine, a travel device and a power transmission unit, the power transmission unit including a torque converter and transmitting an output of the engine to the travel device via the torque converter. The engine output control system includes a speed ratio computation portion and an engine output reduction control portion. The speed ratio computation portion is configured and arranged to compute a speed ratio of the torque converter. The engine output reduction control portion is configured and arranged to reduce an output torque of the engine without changing a target speed of the engine when the computed speed ratio is equal to or less than a speed ratio threshold set in advance. The speed ratio threshold is a speed ratio at which a torque ratio of the torque converter is greater than a torque ratio corresponding to a maximum efficiency.

Abstract: When a blade load is reduced from a value greater than or equal to a first set load value to a value less than the first set load value, a blade control device is configured to set a virtual designed surface to be closer to a blade than a designed surface is, and is configured to allow the blade to pivot above the virtual designed surface.

Abstract: When a blade load is reduced from a value greater than or equal to a first set load value to a value less than the first set load value, a blade control device is configured to set a virtual designed surface to be closer to a blade than a designed surface is, and is configured to allow the blade to pivot above the virtual designed surface.

Abstract: An automatic transmission system for a bulldozer includes an automatic speed stage shifting section that switches among speed stages depending on a vehicle speed, a speed stage maintaining section that maintains a currently selected speed stage until a predetermined speed stage shifting disobedient time elapses after completion of a speed stage shifting while disobeying a switching instruction from the automatic speed stage shifting section, a load detecting section that detects a vehicle load, and a control restricting section that restricts a control processing of the maintaining section for causing it to obey the shifting section's instruction when the vehicle load is a predetermined load or greater even before the disobedient time elapses.

Abstract: A bulldozer includes a blade pivotably attached to a vehicle body, a blade operation lever, and a blade control section. The blade operation lever outputs a lowering instruction signal, a holding instruction signal, and a raising instruction signal for the blade. The blade control section controls a height of the blade according the signal input. The blade control section can lower the blade to a predetermined position when the lowering instruction signal and the holding instruction signal are input in order after a transmission has been switched from a state, which is different from an advancing state, to the advancing state. The blade control section can raise the blade to a predetermined position when the raising instruction signal and the holding instruction signal are input in order after a transmission has been switched from a state, which is different from a reversing state, to the reversing state.

Abstract: A blade control system of the present invention includes a determining part which is configured to determine whether or not a load acting on a blade exceeds a first threshold, and a tilt controlling part which is configured to supply a hydraulic oil to a tilt cylinder for causing the blade to perform a rightward tilt action and a leftward tilt action when the determining part determines that the load acting on the blade exceeds the first threshold.

Abstract: A blade control system includes an angle obtaining part, an open ratio setting part and a lift cylinder controlling part. The angle obtaining part is configured to obtain an angle of a lift frame with respect to a designed surface. The open ratio setting part is configured to set an open ratio based on the angle. The lift cylinder controlling part is configured to open a proportional control valve at the open ratio for elevating the blade when a distance between the designed surface and an edge of a blade is determined to be less than or equal to a threshold.

Abstract: A blade control system of the present invention includes an angle obtaining part, an open ratio setting part and a lift cylinder controlling part. The angle obtaining part is configured to obtain an angle of a lift frame with respect to a designed surface. The open ratio setting part is configured to set an open ratio based on the angle. The lift cylinder controlling part is configured to open a proportional control valve at the open ratio for elevating the blade when a distance between the designed surface and an edge of a blade is determined to be less than or equal to a threshold.

Abstract: A blade control system of the present invention includes a determining part which is configured to determine whether or not a distance between a designed surface and a cutting edge of a blade is less than or equal to a threshold to be determined based on a speed, and a lift cylinder controlling part which is configured to supply hydraulic oil to a lift cylinder for starting elevation of the blade when the determining part determines that the distance is less than or equal to the threshold.

Abstract: A blade system of the present invention includes: a blade angle calculating part configured to calculate sum of a forwardly tilting angle of a vehicle body with respect to a reference surface and a blade lifting angle of a lift frame with respect to a reference position; a difference angle calculating part configured to calculate a difference angle by subtracting a predetermined angle from the sum of the forwardly tilting angle and the blade lifting angle; an opening ratio setting part configured to set an opening ratio of a proportional control valve based on the difference angle; and a lift controlling part configured to control the proportional control valve in accordance with the opening ratio set by the opening ratio setting part until a predetermined period of time is elapsed after onset of dozing by a blade.

Abstract: A transmission control device includes a load increase rate computation portion and a transmission control portion. The load increase rate computation portion is configured to compute an increase rate of a load acting on the work vehicle. The transmission control portion is configured to shift a high-speed gear down to a low-speed gear with producing a lock-up state in which a lock-up clutch is engaged when the load increase rate is less than a load increase rate threshold in shifting the high-speed gear down to the low-speed gear, and producing a torque converter state in which the lock-up clutch is disengaged when the load increase rate is equal to or greater than the load increase rate threshold in shifting the high-speed gear down to the low-speed gear.

Abstract: A blade control system includes a first open ratio setting part for setting a first open ratio of a proportional control valve based on a difference angle between a blade angle and a slope angle; a second open ratio setting part for setting a second open ratio of the proportional control valve based on a difference load between a blade load and a target blade load; and a lift controlling part for controlling the proportional control valve in accordance with the second open ratio when the blade load is out of a predetermined load range and for controlling the proportional control valve in accordance with the first open ratio when the blade load is within the predetermined load range.

Abstract: A brake device lubrication device includes a lubricant supply unit and a control unit. The control unit includes a braking timer, a release timer and a storage unit. The control unit is configured to control the lubricant supply unit so as to supply a predetermined first supply amount of lubricant to a brake device when the brake device is in a braking state, to acquire a delay time corresponding to a braking time counted by the braking timer from a relationship of correspondence between the braking time and the delay time stored by the storage unit when the brake device is switched from the braking state to a released state, and to switch a supply amount of lubricant from the first supply amount to a second supply amount which is smaller than the first supply amount when the release time counted by the release timer reaches the acquired delay time.

Abstract: A blade control system first open ratio setting part for setting a first open ratio of a proportional control valve based on a difference angle between a blade angle and a slope angle; a second open ratio setting part for setting a second open ratio of the proportional control valve based on a difference load between a blade load and a target blade load; and a lift controlling part for controlling the proportional control valve in accordance with the second open ratio when the blade load is out of a predetermined load range and for controlling the proportional control valve in accordance with the first open ratio when the blade load is within the predetermined load range.

Abstract: A blade system of the present invention includes: a blade angle calculating part configured to calculate sum of a forwardly tilting angle of a vehicle body with respect to a reference surface and a blade lifting angle of a lift frame with respect to a reference position; a difference angle calculating part configured to calculate a difference angle by subtracting a predetermined angle from the sum of the forwardly tilting angle and the blade lifting angle; an opening ratio setting part configured to set an opening ratio of a proportional control valve based on the difference angle; and a lift controlling part configured to control the proportional control valve in accordance with the opening ratio set by the opening ratio setting part until a predetermined period of time is elapsed after onset of dozing by a blade.