Abstract: In a vehicle wet-type multi-plate brake device, a piston sleeve 61 is slidably provided between an inner-peripheral surface of a hydraulic piston hole 57 accommodating a piston 55 and an outer-peripheral surface of the piston 55, and has a sliding resistance to move together with the piston 55. A return plate 67 is capable of coming into contact with only the sleeve 61 and of moving by a predetermined distance together with the sleeve 61. When a hydraulic pressure is supplied to an oil chamber 59, the piston 55 and the sleeve 61 move together by a predetermined distance C against a returning force of the return plate 67, and then only the piston 55 slides until coming into contact with a brake plate so that a positional relationship between the piston 55 and the sleeve 61 is constantly maintained and a stroke of the piston 55 is constantly maintained.

Abstract: In a vehicle wet-type multi-plate brake device, an automatic control mechanism is provided which has a simple structure and constantly maintains a piston stroke of a hydraulic piston, the mechanism being reliably operated. A piston sleeve 61 is slidably provided between an inner-peripheral surface of a hydraulic piston hole 57 accommodating a hydraulic piston 55 and an outer-peripheral surface of the hydraulic piston 55, and has a sliding resistance so as to move together with the hydraulic piston 55. Additionally, a return plate 67 is disposed so as to be capable of coming into contact with only the piston sleeve 61 and of moving by a predetermined distance together with the piston sleeve 61.