A system for retarding the speed of a railcar comprises a brake; a hydraulic actuator moving the brake between a closed position in which the brake applies braking pressure on the wheel of a railcar, and an open position in which the brake does not apply braking pressure on the wheel of the railcar; a hydraulic circuit provided with a pump arrangement for supplying hydraulic fluid to the hydraulic actuator; and a control circuit coupled to the hydraulic circuit for controlling the flow of hydraulic fluid to move the brake between the closed and open positions.

A railway wheel includes: a wheel including a plate portion; and a brake disc including a circular plate portion whose front face side is a sliding surface, and a plurality of fin portions which are radially projected on a back face of the circular plate portion, wherein two of the brake discs are fastened in a region within the sliding surface. Regarding an area of a section crossing a space between the brake disc and the wheel along a circumferential direction, a minimum section portion in which the sectional area is minimum is present in a region formed by an outer peripheral surface of the circular plate portion and an inner peripheral surface of the rim portion, and the outer peripheral surface of the circular plate portion follows the inner peripheral surface of the rim portion in a region extending to the outer side from the minimum section portion.

A railway wheel includes: a wheel including a plate portion; and a brake disc including a circular plate portion whose front face side is a sliding surface, and a plurality of fin portions which are radially projected on a back face of the circular plate portion, wherein two of the brake discs are fastened in a region within the sliding surface. Regarding an area of a section crossing a space between the brake disc and the wheel along a circumferential direction, a minimum section portion in which the sectional area is minimum is present in a region formed by an outer peripheral surface of the circular plate portion and an inner peripheral surface of the rim portion, and the outer peripheral surface of the circular plate portion follows the inner peripheral surface of the rim portion in a region extending to the outer side from the minimum section portion.

A brake disc of the present invention is a brake disc that stops the rotation of an axle when a brake pad is pressed on a surface of the brake disc, including a disc main body that is attached to a rotary body integrally rotating with the axle; and a plurality of build-up layers laminated on a surface of the disc main body, in which the build-up layers are laminated on the surface of the disc main body by means of laser metal deposition welding.

A brake disc of the present invention is a brake disc that stops the rotation of an axle when a brake pad is pressed on a surface of the brake disc, including a disc main body that is attached to a rotary body integrally rotating with the axle; and a plurality of build-up layers laminated on a surface of the disc main body, in which the build-up layers are laminated on the surface of the disc main body by means of laser metal deposition welding.

A parking brake unit of a brake device for braking a wheel includes a first piston having a first engaging part on an inner circumference thereof, the first piston being configured to move in first direction by pressure of the hydraulic fluid supplied to a pressure chamber defined in the back thereof, a first biasing member configured to bias the first piston in second direction, opposite to the first direction, a second piston slidably provided on the inner circumference of the first piston, the second piston having a second engaging part on an outer circumference thereof, and an engaging member configured to cause the first engaging part and the second engaging part to engage with each other, in which the second piston causes a brake lining to move in direction bringing the wheel to be in a braking state, when the first piston moves in the second direction.

A parking brake unit of a brake device for braking a wheel includes a first piston having a first engaging part on an inner circumference thereof, the first piston being configured to move in first direction by pressure of the hydraulic fluid supplied to a pressure chamber defined in the back thereof, a first biasing member configured to bias the first piston in second direction, opposite to the first direction, a second piston slidably provided on the inner circumference of the first piston, the second piston having a second engaging part on an outer circumference thereof, and an engaging member configured to cause the first engaging part and the second engaging part to engage with each other, in which the second piston causes a brake lining to move in direction bringing the wheel to be in a braking state, when the first piston moves in the second direction.

The invention relates to a railway braking system (1) comprising a first pneumatic distribution device (51) formed by a first distributor provided with a single inlet opening (54a,b) connected to a source for supplying pneumatic pressure mediums (73) and with a single outlet opening (55a,b) connected to a parking brake chamber (25) in order to optionally supply a parking brake (7) with a second pneumatic pressure medium so as to place said brake in either of inoperative and operative configurations, and a second pneumatic distribution device (61) formed by a second distributor provided with a single inlet opening (64a,b) connected to said supply source and with a single outlet opening (65a,b) connected to a service pressure chamber (13) in order to supply a service brake (6) with a third pneumatic pressure medium of which the pressure value is predetermined, so as to apply a predetermined braking force when said parking brake is in the operative configuration thereof.

The invention relates to a railway braking system (1) comprising a first pneumatic distribution device (51) formed by a first distributor provided with a single inlet opening (54a,b) connected to a source for supplying pneumatic pressure mediums (73) and with a single outlet opening (55a,b) connected to a parking brake chamber (25) in order to optionally supply a parking brake (7) with a second pneumatic pressure medium so as to place said brake in either of inoperative and operative configurations, and a second pneumatic distribution device (61) formed by a second distributor provided with a single inlet opening (64a,b) connected to said supply source and with a single outlet opening (65a,b) connected to a service pressure chamber (13) in order to supply a service brake (6) with a third pneumatic pressure medium of which the pressure value is predetermined, so as to apply a predetermined braking force when said parking brake is in the operative configuration thereof.

A parking brake reduced in size and simplified is installed on a rod-protruding side of a cylinder of a caliper braking device. A second piston is provided within the second cylinder that is coaxially coupled with the cylinder and movable coaxially relative to the rod. A one-way clutch is provided to switch ON/OFF due to a releasing/pressing by the second piston with respect to a switch disposed facing a cylinder side surface of the second piston. A parking operation auxiliary spring is provided on the side of the cylinder within a second cylinder, and a manual release piston is provided in a space of the second cylinder. A parking release lever pushes a manual release rod at the tip end of the manual release piston, pushing the second piston in the direction of retraction of the rod, at the same time as the manual release rod pushes into the rod.