A hydraulic circuit comprising: a first working fluid supply; a second working fluid supply; a confluence valve connected to the first working fluid supply to control a flow of working fluid provided by the first working fluid supply; a first control valve and a second control valve connected to the second working fluid supply to control a flow of working fluid provided by the second working fluid supply; a first fluid passage comprising a first portion and connected to the confluence valve to move the confluence valve; a second fluid passage comprising a second portion fluidly communicating with the first portion of the first fluid passage, the second fluid passage extending from the second portion through the second control valve; a third fluid passage comprising a third portion fluidly communicating with the first portion of the first fluid passage and the second portion of the second fluid passage, the third fluid passage extending from the third portion; a first valve opening and closing the third fluid passage; a fourth fluid passage comprising a fourth portion and connected to the first valve to move the first valve; a fifth fluid passage comprising a fifth portion fluidly communicating with the fourth portion of the fourth fluid passage, the fifth fluid passage extending from the fifth portion through the first control valve, wherein, when the first control valve and the second control valve are in non-neutral positions, respectively, the fifth fluid passage and the second fluid passage are closed, thereby generating a first pressure within the fifth portion of the fifth fluid passage and a second pressure within the second portion of the second fluid passage, so that the first pressure is applied to the first valve through the fourth fluid passage to move the first valve to close the third fluid passage and the second pressure is applied to the confluence valve through the first fluid passage to move the confluence valve to a confluence position, and when the confluence valve is in the confluence position, the confluence valve directs working fluid from the first working fluid supply to the second control valve, characterized in that the hydraulic circuit further comprises a second valve provided on the first fluid passage; and a seventh fluid passage extending from the second valve, wherein the second valve has at least a first position and a second position, and the second valve allows fluid communication between the first fluid passage and the seventh fluid passage in the first position and blocks fluid communication between the first fluid passage and the seventh fluid passage in the second position. a first working fluid supply; a second working fluid supply; a confluence valve connected to the first working fluid supply to control a flow of working fluid provided by the first working fluid supply; a first control valve and a second control valve connected to the second working fluid supply to control a flow of working fluid provided by the second working fluid supply; a first fluid passage comprising a first portion and connected to the confluence valve to move the confluence valve; a second fluid passage comprising a second portion fluidly communicating with the first portion of the first fluid passage, the second fluid passage extending from the second portion through the second control valve; a third fluid passage comprising a third portion fluidly communicating with the first portion of the first fluid passage and the second portion of the second fluid passage, the third fluid passage extending from the third portion; a first valve opening and closing the third fluid passage; a fourth fluid passage comprising a fourth portion and connected to the first valve to move the first valve; a fifth fluid passage comprising a fifth portion fluidly communicating with the fourth portion of the fourth fluid passage, the fifth fluid passage extending from the fifth portion through the first control valve, wherein, when the first control valve and the second control valve are in non-neutral positions, respectively, the fifth fluid passage and the second fluid passage are closed, thereby generating a first pressure within the fifth portion of the fifth fluid passage and a second pressure within the second portion of the second fluid passage, so that the first pressure is applied to the first valve through the fourth fluid passage to move the first valve to close the third fluid passage and the second pressure is applied to the confluence valve through the first fluid passage to move the confluence valve to a confluence position, and when the confluence valve is in the confluence position, the confluence valve directs working fluid from the first working fluid supply to the second control valve, characterized in that the hydraulic circuit further comprises a second valve provided on the first fluid passage; and a seventh fluid passage extending from the second valve, wherein the second valve has at least a first position and a second position, and the second valve allows fluid communication between the first fluid passage and the seventh fluid passage in the first position and blocks fluid communication between the first fluid passage and the seventh fluid passage in the second position.