Hydraulic system for work machine, and work machine

A hydraulic system for a work machine, comprising:

• a hydraulic pump to supply a pilot fluid;
• a hydraulic switch valve to be switched to a plurality of switching positions based on a pilot pressure, the pilot pressure being a pressure of the pilot fluid supplied from the hydraulic pump;
• a direction switch valve to apply a first pilot pressure to the hydraulic switch valve to switch the hydraulic switch valve into one of the plurality of switching positions;
• and
• a speed reducing device to reduce a speed of changing the pilot pressure to be changed to the first pilot pressure,
• wherein the speed reducing device includes
• a second fluid tube connecting the direction switch valve to the hydraulic switch valve,
• a second throttle to reduce the pilot pressure in the second fluid tube,
• a third an other fluid tube connecting the hydraulic switch valve to a tank to which the pilot fluid is to be discharged from the hydraulic switch valve, and
• a third an other throttle to reduce an amount of the pilot fluid flowing in the third other fluid tube,
• wherein the second throttle and the third other throttle reduce the speed of changing the pilot pressure.

A hydraulic system for a work machine, comprising:

• a hydraulic pump to supply a pilot fluid;
• a hydraulic switch valve to be switched to a plurality of switching positions based on a pilot pressure, the pilot pressure being a pressure of the pilot fluid supplied from the hydraulic pump;
• a direction switch valve to apply a first pilot pressure to the hydraulic switch valve to switch the hydraulic switch valve into one of the plurality of switching positions;
• a pressure applying device to apply a second pilot pressure to the hydraulic switch valve, the second pilot pressure being lower than the first pilot pressure;
• and
• a speed reducing device to reduce a speed of changing the pilot pressure, the pilot pressure being to be applied to the hydraulic switch valve and to be changed to the first pilot pressure.

A hydraulic system for a work machine, comprising:

• a hydraulic pump to supply a pilot fluid;
• a hydraulic switch valve to be switched to a plurality of switching positions based on a pilot pressure, the pilot pressure being a pressure of the pilot fluid supplied from the hydraulic pump;
• a direction switch valve to apply a first pilot pressure to the hydraulic switch valve to switch the hydraulic switch valve into one of the plurality of switching positions;
• a pressure applying device to apply a second pilot pressure to the hydraulic switch valve, the second pilot pressure being lower than the first pilot pressure;
• a second fluid tube connecting the direction switch valve to the hydraulic switch valve;
• a fourth an other fluid tube connecting the hydraulic pump to the direction switch valve;
• and
• a discharge fluid tube which is connected to the direction switch valve and through which the pilot fluid in the second fluid tube is to be introduced from the direction switch valve,
• wherein the direction switch valve is switchable between a first position and a second position, the direction switch valve being switched to the first position such that the second fluid tube communicates with the discharge fluid tube to relieve the pilot fluid in the second fluid tube, the direction switch valve being switched to the second position such that the fourth other fluid tube communicates with the second fluid tube to apply the first pilot pressure to the hydraulic switch valve.

A hydraulic system for a work machine, comprising:

• a hydraulic pump to supply a pilot fluid;
• a hydraulic switch valve to be switched to a plurality of switching positions based on a pilot pressure, the pilot pressure being a pressure of the pilot fluid supplied from the hydraulic pump;
• a direction switch valve to apply a first pilot pressure to the hydraulic switch valve to switch the hydraulic switch valve into one of the plurality of switching positions;
• a speed reducing device to reduce a speed of changing the pilot pressure to be changed to the first pilot pressure;
• a second fluid tube connecting the direction switch valve to the hydraulic switch valve;
• a fourth an other fluid tube connecting the hydraulic pump to the direction switch valve;
• and
• a discharge fluid tube which is connected to the direction switch valve and through which the pilot fluid in the second fluid tube is to be introduced from the direction switch valve,
• wherein the direction switch valve is switchable between a first position and a second position, the direction switch valve being switched to the first position such that the second fluid tube communicates with the discharge fluid tube to relieve the pilot fluid in the second fluid tube, the direction switch valve being switched to the second position such that the fourth other fluid tube communicates with the second fluid tube to apply the first pilot pressure to the hydraulic switch valve.

A hydraulic system for a work machine, comprising:

• a hydraulic pump to supply a pilot fluid;
• a hydraulic switch valve to be switched to a plurality of switching positions based on a pilot pressure, the pilot pressure being a pressure of the pilot fluid supplied from the hydraulic pump;
• a direction switch valve to apply a first pilot pressure to the hydraulic switch valve to switch the hydraulic switch valve into one of the plurality of switching positions;
• a pressure applying device to apply a second pilot pressure to the hydraulic switch valve, the second pilot pressure being lower than the first pilot pressure;
• and
• a second fluid tube connecting the direction switch valve to the hydraulic switch valve,
• wherein the direction switch valve is a proportional valve to change an aperture to change a pilot pressure that is a pressure of the pilot fluid flowing in the second fluid tube,
• and wherein the pressure applying device is to set the aperture of the proportional valve to maintain the pilot pressure in the second fluid tube to be less than the first pilot pressure.

A hydraulic system for a work machine, comprising:

• a hydraulic pump to supply a pilot fluid;
• a hydraulic switch valve to be switched to a plurality of switching positions based on a pilot pressure, the pilot pressure being a pressure of the pilot fluid supplied from the hydraulic pump;
• a direction switch valve to apply a first pilot pressure to the hydraulic switch valve to switch the hydraulic switch valve into one of the plurality of switching positions;
• a speed reducing device to reduce a speed of changing the pilot pressure to be changed to the first pilot pressure;
• a second fluid tube connecting the direction switch valve to the hydraulic switch valve;
• and
• a speed controller to control a speed of changing the pilot pressure to be changed to the first pilot pressure,
• wherein the direction switch valve is a proportional valve to change an aperture to change the pilot pressure in the second fluid tube,
• and wherein the speed controller includes the speed reducer reducing device to change a reduce the speed of changing the aperture of the proportional valve to reduce the speed of changing the pilot pressure to be changed to the first pilot pressure.

A hydraulic system for a work machine, comprising:

• a hydraulic pump to supply a pilot fluid;
• a hydraulic switch valve to be switched to a plurality of switching positions based on a pilot pressure, the pilot pressure being a pressure of the pilot fluid supplied from the hydraulic pump;
• a direction switch valve to apply a first pilot pressure to the hydraulic switch valve to switch the hydraulic switch valve into one of the plurality of switching positions;
• a speed reducing device to reduce a speed of changing the pilot pressure to be changed to the first pilot pressure;
• a second fluid tube connecting the direction switch valve to the hydraulic switch valve;
• and
• a speed controller including the speed reducer reducing device to change a reduce the speed of changing the pilot pressure to be changed to the first pilot pressure;
• and
• a first travel sensor to detect a travel speed,
• wherein the direction switch valve is a proportional valve to change an aperture to change the pilot pressure in the second fluid tube,
• wherein the speed controller is to set a speed of changing the aperture of the proportional valve to a first changing speed corresponding to a first speed when the travel speed is the first speed, and to set the speed of changing the aperture of the proportional valve to a second changing speed corresponding to a second speed when the travel speed is the second speed,
• and wherein the first changing speed is lower than the second changing speed.

A hydraulic system for a work machine, comprising:

• a hydraulic pump to supply a pilot fluid;
• a hydraulic switch valve to be switched to a plurality of switching positions based on a pilot pressure, the pilot pressure being a pressure of the pilot fluid supplied from the hydraulic pump;
• a direction switch valve to apply a first pilot pressure to the hydraulic switch valve to switch the hydraulic switch valve into one of the plurality of switching positions;
• a speed reducing device to reduce a speed of changing the pilot pressure to be changed to the first pilot pressure;
• a second fluid tube connecting the direction switch valve to the hydraulic switch valve;
• a speed controller including the speed reducer reducing device to change a reduce the speed of changing the pilot pressure to be changed to the first pilot pressure;
• and
• a second travel sensor to detect an operation being in traveling and an operation being in non-traveling a travel detector to detect whether a travel speed is zero in a non-traveling state or the travel speed is greater than zero in a traveling state,
• wherein the direction switch valve is a proportional valve to change an aperture to change the pilot pressure in the second fluid tube,
• wherein the speed controller is to set a speed of changing the aperture of the proportional valve to a third changing speed corresponding to a state of the traveling state and to a fourth an other changing speed corresponding to a state of the non-traveling state,
• and wherein the third changing speed is lower than the fourth other changing speed.