HYDRAULIC SYSTEM OF INDUSTRIAL VEHICLE

A hydraulic system (1) of an industrial vehicle (2) includes an oil tank (5) in which hydraulic oil is retained; a hydraulic pump (6, 16) that draws in the hydraulic oil from the tank (5) and supply the oil to a loading actuator (9, 10) and a brake unit (15); a brake valve (18) that controls the hydraulic oil to be supplied to the brake unit (15) according to an operation of a brake operation tool (14); a hydraulic oil cooler (19) that cools the hydraulic oil; a cooling passage (20) that allows the hydraulic oil to flow toward the cooler (19) and further allows the oil cooled in the cooler (19) to flow toward the brake unit (15); and a switching valve (21, 50) that switches between a first oil passage (21a, 50a) that cuts off a supply of the hydraulic oil from the hydraulic pump (16) to the cooling passage (20) and a second oil passage (21b, 50b) that allows the supply of the hydraulic oil from the hydraulic pump (16) to the cooling passage (20).