Patent Description:
<CIT> discloses a brake caliper for applying a braking force to a wheel of a railway vehicle by forcing a brake pad against a disc that rotates integrally with the wheel. The brake caliper includes a cylinder device workable with a fluid such as compressed air and a caliper lever connected to the cylinder device and rotatable by the cylinder device such that the brake pad approaches or separates away from the disc.

<CIT> discloses a brake caliper according to the preamble of claim <NUM> and claims <NUM>.

The brake caliper is rotatably attached to a bogie, so that the disc and brake pad remain parallel to each other even if the bogie becomes inclined relative to the axle while the railway vehicle travels. With such arrangement, however, the brake caliper may be undesirably rotated by the vibration generated during the traveling of the railway vehicle. As a result, the brake pads may touch the disc even though no brake force is generated or no braking is applied. The same problem may arise in brake calipers used in disc brake devices used in industrial vehicles including not only railway vehicles but also trucks, buses, and vehicles for work at high level.

It is an object of the present invention to provide a brake caliper that makes it difficult for the body to rotate relative to the bracket. According to the present invention said object is solved by a brake caliper having the features of the independent claim <NUM>. Said object is solved by a brake caliper having the features of the independent claim <NUM>. Preferred embodiments are laid down in the dependent claims.

A brake caliper includes a pair of caliper levers, where each caliper lever retains a brake pad, an actuator for outputting a force to rotate the caliper levers such that the caliper levers press a disc, a body retaining the caliper levers in a rotatable manner and retaining the actuator, a bracket fixedly attached to a bogie, a coupling pin coupling the body to the bracket such that the body and the bracket are rotatable relative to each other around a rotational axis extending in a longitudinal direction of the caliper levers, and a friction applying unit penetrated by the coupling pin, the friction applying unit being configured to restrain rotation of the body by generating sliding friction at a contact surface of the friction applying unit where the friction applying unit touches the body or the bracket.

With such a design, the friction applying unit generates a frictional force against the relative rotation between the body and the bracket, making it difficult for the body to rotate relative to the bracket. This prevents unintended contact between the brake pads and the disc when the brake is not in operation. In addition, since the friction applying unit penetrated by the coupling pin generates sliding friction at the contact surface in the axial direction surrounding the coupling pin and prevents the rotation, friction is applied in a more stabilized manner than in a case where friction is applied only at part of the body or bracket.

A brake caliper includes a pair of caliper levers, where each caliper lever retains a brake pad, an actuator for outputting a force to rotate the caliper levers such that the caliper levers press a disc, a body retaining the caliper levers in a rotatable manner and retaining the actuator, a bracket fixedly attached to a bogie, a coupling pin supporting the body such that the body is rotatable relative to the bracket around a rotational axis extending in a longitudinal direction of the caliper levers, and a friction applying unit configured to restrain rotation of the coupling pin by generating sliding friction at a contact surface of the friction applying unit where the friction applying unit touches an end of the coupling pin in an axial direction, wherein the friction applying unit is provided in the body or the bracket.

With such a design, the friction applying unit generates a frictional force against the rotation relative to the coupling pin, thereby making it difficult for the body to rotate relative to the bracket. This prevents unintended contact between the brake pads and the disc when the brake is not in operation. In addition, since the friction applying unit generates sliding friction at the contact surface of the friction applying unit where the friction applying unit touches the end of the coupling pin in the axial direction and prevents the rotation, friction is applied in a more stabilized manner than in a case where friction is applied only at part of the body or bracket.

The present invention prevents unintended contact between brake pads and a disc while no braking is applied.

With reference to <FIG>, a first embodiment of a brake caliper will now be described.

As shown in <FIG> and <FIG>, a brake caliper <NUM> is mounted to a bogie (not shown) of a railway vehicle and configured to apply a braking force to a wheel of the bogie by pressing brake pads <NUM> against a disc <NUM> (see <FIG>) rotating integrally with an axle rotating the wheel. The brake caliper <NUM> and the disc <NUM> together constitute a disc brake device.

The brake caliper <NUM> includes a bracket <NUM> (see <FIG>) mounted to the bogie, a body <NUM> rotatably hung on the bracket <NUM>, and a pair of left and right caliper levers <NUM> and <NUM> held by the body <NUM>. The body <NUM> retains the pair of left and right caliper levers <NUM> and <NUM> turnably, so that the brake pads <NUM> are movable to a position where they sandwich the disc <NUM> and a position where they do not sandwich the disc <NUM>.

The brake caliper <NUM> also includes a cylinder device <NUM> for outputting a force through compressed air fed thereto and discharged therefrom, and the force causes the left and right caliper levers <NUM> and <NUM> to sandwich the disc <NUM> via the brake pads <NUM>. The compressed air fed to the cylinder device <NUM> is taken from a tank installed on the railway vehicle. The cylinder device <NUM> is removably mounted to the body <NUM>. Here, the cylinder device <NUM> corresponds to an actuator.

As shown in <FIG>, the bracket <NUM> includes a first bracket 21A and a second bracket 21B. The body <NUM> is disposed between the first bracket 21A and the second bracket 21B. A coupling pin <NUM> penetrates through the first bracket 21A, the body <NUM>, and the second bracket 21B to couple together the first bracket 21A, the body <NUM>, and the second bracket 21B. The body <NUM> has a base portion <NUM> through which the coupling pin <NUM> penetrates. The base portion <NUM> rotates about a rotational axis P that extends orthogonal to the axial direction of the axle of the bogie and extends along a direction in which the left and right caliper levers <NUM> and <NUM> extend (see <FIG>).

The brake caliper <NUM> is rotatably attached to the bogie, so that the disc <NUM> and brake pads <NUM> remain parallel to each other even if the bogie becomes inclined while the railway vehicle travels. With such arrangement, the brake caliper <NUM> may be undesirably rotated by the vibration generated during the traveling of the railway vehicle. As a result, the brake pads <NUM> may touch the disc <NUM> even though no brake force is generated or no braking is applied.

To address this issue, as shown in <FIG> and <FIG>, the brake caliper <NUM> includes a friction applying unit <NUM> for increasing the frictional force resulting from the relative movement between the bracket <NUM> and the body <NUM> as the body <NUM> rotates. The friction applying unit <NUM> is provided in the second bracket 21B. The friction applying unit <NUM> is penetrated by the coupling pin <NUM> and configured to, as the body <NUM> and the second bracket 21B rotate relative to each other, generate sliding friction at the contact surface of the body <NUM>, in the axial direction, surrounding the coupling pin <NUM>. The friction applying unit <NUM> serves as a rotation restraining unit for restraining the rotation of the coupling pin <NUM>. The friction applying unit <NUM> includes a friction ring <NUM>, which is a pressing member, for generating a frictional force when pressed against the body <NUM>. The friction ring <NUM> is penetrated by the coupling pin <NUM>. The friction applying unit <NUM> includes a spring <NUM>, which is an energizing member, for generating a frictional force by energizing the friction ring <NUM>. The spring <NUM> includes three disc springs. Alternatively, the spring <NUM> may include one, two or four or more disc springs, and the number of disc springs may be determined by a required energizing force. The spring <NUM> is penetrated by the coupling pin <NUM>.

The bracket <NUM> retain the coupling pin <NUM> at the respective ends thereof. In other words, the first bracket 21A retains a first end portion 22A of the coupling pin <NUM>, and the second bracket 21B retains a second end portion 22B of the coupling pin <NUM>. The first end portion 22A of the coupling pin <NUM> has a greater diameter than the second end portion 22B opposite the first end portion 22A. Accordingly, the coupling pin <NUM> is inserted into the body <NUM> from the side facing the first bracket 21A. The first end portion 22A of the coupling pin <NUM> is press-fit into the first bracket 21A. The coupling pin <NUM> is inserted into the second bracket 21B and fixedly secured by a bolt <NUM>. A ring <NUM> is sandwiched between the coupling pin <NUM> and the head of the bolt <NUM>. A first bushing <NUM> is attached to a portion of the body <NUM> that touches the first bracket 21A. The first bushing <NUM> is divided into a planar portion shaped like a disc and a tubular portion shaped like a cylinder. The planar portion of the first bushing <NUM> touches the first bracket 21A. The first bushing <NUM> is made of a softer material than the first bracket 21A. A second busing <NUM> is attached to a portion of the body <NUM> that touches the second bracket 21B and the friction ring <NUM>. The second bushing <NUM> is divided into a planar portion shaped like a disc and a tubular portion shaped like a cylinder. The planar portion of the second bushing <NUM> touches the second bracket 21B and the friction ring <NUM>. The second bushing <NUM> is made of a softer material than the second bracket 21B and the friction ring <NUM>. The second bushing <NUM> corresponds to a contact member.

As the spring <NUM> of the friction applying unit <NUM> energizes the body <NUM>, the second bracket 21B is energized in such a direction that the second bracket 21B separates away from the base portion <NUM> of the body <NUM>. As a result, the coupling pin <NUM> as well as the second bracket 21B is pulled, so that the first bracket 21A fixedly attached to the first end portion 22A of the coupling pin <NUM> is pressed against the base portion <NUM> of the body <NUM>. The friction applying unit <NUM> thus generates a frictional force at the contact surface between the body <NUM> and the second bracket 21B and also generates a frictional force at the contact surface between the first bracket 21A and the body <NUM>. If the body <NUM> attempts to rotate relative to the bracket <NUM>, sliding friction is generated between the friction ring <NUM> and the second bushing <NUM>, thereby restraining the rotation.

As shown in <FIG>, the body <NUM> includes a first support portion <NUM> that extends from below the base portion <NUM> toward the left and right caliper levers <NUM> and <NUM> to support the left and right caliper levers <NUM> and <NUM>. The body <NUM> also includes a second support portion <NUM> that extends from the center of the first support portion <NUM> toward the rear side in the longitudinal direction of the left and right caliper levers <NUM> and <NUM> to support the cylinder device <NUM>. The second support portion <NUM> is a plate-shaped member. The base portion <NUM>, the first support portion <NUM>, and the second support portion <NUM> of the body <NUM> are formed as a single unit body. When the bogie is tilted in the axial direction of the axle, the body <NUM> turns about the rotational axis P. This enables the brake pads <NUM> to always remain parallel to the disc <NUM>.

A left support portion 32A supporting the left caliper lever <NUM> is provided on the left portion of the first support portion <NUM>. A left rotation pin <NUM> penetrates the left support portion 32A to rotatably support the left caliper lever <NUM>. The left rotation pin <NUM> is rotatable relative to the left support portion 32A. An operation lever 35A is fixedly attached to the left rotation pin <NUM> and is operated by a driving force from the cylinder device <NUM>. A right support portion 32B supporting the right caliper lever <NUM> is provided on the right portion of the first support portion <NUM>. Right rotation pins <NUM> penetrate through upper and lower portions of the right support portion 32B respectively to rotatably support the right caliper lever <NUM>. The right rotation pins <NUM> are rotatable relative to the right support portion 32B.

As shown in <FIG>, the left caliper lever <NUM> includes a pair of left upper lever <NUM> and a left lower lever <NUM>. The left upper and lower levers <NUM> and <NUM> are spaced away from each other and face each other in the axial direction of the left rotation pin <NUM>. At the tip end portion of the left caliper lever <NUM>, a pad attachment member <NUM> is connected via two pad rotation pins <NUM>. To the pad attachment member <NUM>, the brake pad <NUM> is attached. The pad rotation pins <NUM> are rotatable relative to the left upper and lower levers <NUM> and <NUM>. The pad rotation pins <NUM> are fixedly attached to the pad attachment member <NUM>. The left upper and lower levers <NUM> and <NUM> are coupled together via a left lever coupling pin <NUM>.

The right caliper lever <NUM> includes a pair of a right upper lever <NUM> and a right lower lever <NUM>. The right upper and lower levers <NUM> and <NUM> are spaced away from each other and face each other in the axial direction of the right rotation pin <NUM>. At the tip end portion of the right caliper lever <NUM>, a pad attachment member <NUM> is connected via two pad rotation pins <NUM>. To the pad attachment member <NUM>, the brake pad <NUM> is attached. The pad rotation pins <NUM> are rotatable relative to the right upper and lower levers <NUM> and <NUM>. The pad rotation pins <NUM> are fixedly attached to the pad attachment member <NUM>. The right upper and lower levers <NUM> and <NUM> are coupled together via a right lever coupling pin <NUM>.

As shown in <FIG>, the cylinder device <NUM> is mounted to the second support portion <NUM> of the body <NUM>. The cylinder device <NUM> includes a service brake cylinder <NUM> and a parking brake cylinder <NUM>. The service brake cylinder <NUM> and the parking brake cylinder <NUM> are mounted to surfaces of the second support portion <NUM> that are perpendicular to the axle. The service brake cylinder <NUM> is mounted to the left-side surface of the second support portion <NUM> of the body <NUM>. The parking brake cylinder <NUM> is mounted to the right-side surface of the second support portion <NUM> of the body <NUM>. This means that the service and parking brake cylinders <NUM> and <NUM> sandwich the second support portion <NUM> of the body <NUM>. The surfaces of the second support portion <NUM> to which the service and parking brake cylinders <NUM> and <NUM> are mounted are parallel to the direction in which the left and right caliper levers <NUM> and <NUM> extend and are parallel to the surface of the brake pads <NUM>.

As shown in <FIG>, the service and parking brake cylinders <NUM> and <NUM> are each fixed to the second support portion <NUM> with four bolts. The service and parking brake cylinders <NUM> and <NUM> are bolted to the second support portion <NUM> at different positions. Therefore, the service and parking brake cylinders <NUM> and <NUM> can be mounted to and removed from the second support portion <NUM> independently from each other.

As shown in <FIG>, the second support portion <NUM> of the body <NUM> has an opening 33A formed in the middle thereof. The opening 33A is elongated in the longitudinal direction of the left and right caliper levers <NUM> and <NUM>. With such a design, in mounting and removing the service and parking brake cylinders <NUM> and <NUM>, they can be moved in the opening 33A in the longitudinal direction of the left and right caliper levers <NUM> and <NUM>.

The service brake cylinder <NUM> can be removed from the left-side surface of the second support portion <NUM> of the body <NUM> by taking off bolts. The parking brake cylinder <NUM> can be removed from the right-side surface of the second support portion <NUM> of the body <NUM> by taking off the bolts. The gap adjustment device <NUM> can be removed from the left and right caliper levers <NUM> and <NUM> by taking off bolts <NUM> and <NUM>. With such a design, the cylinder device <NUM> and the gap adjustment device <NUM> can be readily removed and mounted for inspection and replacement. Any number of bolts may be used to fix the cylinder device <NUM>.

The service brake cylinder <NUM> includes a first cylinder chamber <NUM>, a first piston <NUM>, a first rod <NUM>, and a first spring <NUM>. The first piston <NUM> moves within the first cylinder chamber <NUM>. The first rod <NUM> is fixed to the first piston <NUM> and projects from the first cylinder chamber <NUM>. The first spring <NUM> energizes the first piston <NUM> in such a direction that the first rod <NUM> is housed in the first cylinder chamber <NUM>. A first space <NUM> is defined in the first cylinder chamber <NUM> as the space not including the first spring <NUM>. The service brake cylinder <NUM> includes a first feeding port <NUM> for feeding compressed air into the first space <NUM> within the first cylinder chamber <NUM> (see <FIG>). The first feeding port <NUM> is provided outside the first cylinder chamber <NUM>. When the compressed air is fed into the first space <NUM> within the first cylinder chamber <NUM> of the service brake cylinder <NUM>, the first piston <NUM> is pushed such that the first rod <NUM> projects. When the compressed air is discharged from the first space <NUM> within the first cylinder chamber <NUM> of the service brake cylinder <NUM>, the first spring <NUM> pushes the first piston <NUM> so that the first rod <NUM> is accommodated in the first cylinder chamber <NUM>. The first rod <NUM> corresponds to an output rod of the service brake cylinder <NUM>. The first cylinder chamber <NUM> corresponds to a casing of the service brake cylinder <NUM>.

The parking brake cylinder <NUM> includes a second cylinder chamber <NUM>, a second piston <NUM>, a second rod <NUM>, and a second spring <NUM>. The second piston <NUM> moves within the second cylinder chamber <NUM>. The second rod <NUM> is fixed to the second piston <NUM> and projects from the second cylinder chamber <NUM> and extends into the first cylinder chamber <NUM>. The second spring <NUM> energizes the second piston <NUM> in such a direction that the second rod <NUM> projects from the second cylinder chamber <NUM>. A second space <NUM> is defined in the second cylinder chamber <NUM> as the space not including the second spring <NUM>. The parking brake cylinder <NUM> includes a second feeding port <NUM> (see <FIG>) for feeding compressed air into the second space <NUM> within the second cylinder chamber <NUM>. The second feeding port <NUM> is provided outside the second cylinder chamber <NUM>. When the compressed air is fed into the second space <NUM> within the second cylinder chamber <NUM> of the parking brake cylinder <NUM>, the second piston <NUM> is pushed such that the second rod <NUM> is accommodated into the second cylinder chamber <NUM>. When the compressed air is discharged from the second space <NUM> in the second cylinder chamber <NUM> of the parking brake cylinder <NUM>, the second spring <NUM> pushes the second piston <NUM>, so that the second rod <NUM> projects from the second cylinder chamber <NUM> and enters the first cylinder chamber <NUM>. As a result, the second rod <NUM> pushes the first piston <NUM>, so that the first rod <NUM> projects outside. The second rod <NUM> corresponds to an output shaft of the parking brake cylinder <NUM>. The second cylinder chamber <NUM> corresponds to a casing of the parking brake cylinder <NUM>.

The first cylinder chamber <NUM> includes a first projecting portion 71A that projects into the opening 33A. The second cylinder chamber <NUM> includes a second projecting portion 81A that projects into the opening 33A. The second projecting portion 81A is penetrated by the second rod <NUM>. The first projecting portion 71A is fitted around the second projecting portion 81A. With such arrangement, the first rod <NUM> of the service brake cylinder <NUM> and the second rod <NUM> of the parking brake cylinder <NUM> are positioned coaxially, and the output of the parking brake cylinder <NUM> is transmitted to the service brake cylinder <NUM>.

A rotatable roller 35B is attached to the tip end of the operation lever 35A. The first rod <NUM> of the cylinder device <NUM> has a receiving portion 73A provided in the tip end thereof. The receiving portion 73A is a through-hole for receiving therein the roller 35B while touching the roller 35B. The receiving portion 73A is configured to transmit the driving force from the first rod <NUM> to the operation lever 35A, while absorbing the lag between the linear movement of the first rod <NUM> and the rotational movement of the operation lever 35A.

As shown in <FIG> and <FIG>, the brake caliper <NUM> includes the gap adjustment device <NUM> for adjusting the gaps between the brake pads <NUM> and the disc <NUM>. The gap adjustment device <NUM> includes a gap adjuster <NUM> for adjusting the gaps and a gap outputting unit <NUM> for outputting a gap to the gap adjuster <NUM>. The gap outputting unit <NUM> includes a pulling unit <NUM> and a wire <NUM>. The pulling unit <NUM> is configured to pull the wire <NUM> to an extent determined by the amount of the movement of the first rod <NUM> of the cylinder device <NUM>. The gap adjuster <NUM> connects between the base end portion of the left caliper lever <NUM> and the base end portion of the right caliper lever <NUM>. The left caliper lever <NUM> and the gap adjuster <NUM> are rotatably coupled with each other with a pair of upper and lower bolts <NUM>. The right caliper lever <NUM> and the gap adjuster <NUM> are rotatably coupled with each other with a pair of upper and lower bolts <NUM>. The left caliper lever <NUM> and the gap adjuster <NUM> rotate about a rotational axis <NUM>, and the right caliper lever <NUM> and the gap adjuster <NUM> rotate about a rotational axis <NUM>.

The gap adjustment device <NUM> adjusts the distance between the base end portion of the left caliper lever <NUM> and the base end portion of the right caliper lever <NUM> to adjust the gaps between the brake pads <NUM> and the disc <NUM>. As the brake pads <NUM> wear off, the gap grows between the brake pads <NUM> and the disc <NUM>. To deal with this issue, the gap adjustment device <NUM> increases the distance between the base end portion of the left caliper lever <NUM> and the base end portion of the right caliper lever <NUM>, thereby reducing the distance between the brake pads <NUM> and the disc <NUM>.

In the gap adjustment device <NUM>, the pulling unit <NUM> pulls the wire <NUM> if the first rod <NUM> moves by a predetermined amount or more. In other words, if the first rod <NUM> protrudes and the amount of the protrusion reaches a predetermined value, the first rod <NUM> touches the pulling unit <NUM>, as a result of which the pulling unit <NUM> rotates and accordingly pulls the wire <NUM>.

As shown in <FIG>, the gap adjuster <NUM> includes a first casing <NUM> and a second casing <NUM>. The first casing <NUM> connects between the respective base end portions of the left upper and lower levers <NUM> and <NUM>. The first casing <NUM> is rotatably coupled with the left upper and lower levers <NUM> and <NUM> via the bolts <NUM>. The second casing <NUM> connects between the respective base end portions of the right upper and lower levers <NUM> and <NUM>. The second casing <NUM> is rotatably coupled with the right upper and lower levers <NUM> and <NUM> via the bolts <NUM>.

As shown in <FIG>, the first casing <NUM> includes an extension portion 121A having a cylindrical shape and extending toward the second casing <NUM>. A polygonal rod <NUM> shaped like a polygonal column is fixed to the first casing <NUM>. The polygonal rod <NUM> extends in the direction in which the extension portion 121A of the first casing <NUM> extends.

The tip end portion of the polygonal rod <NUM> protrudes out of the first casing <NUM>. The tip end portion of the polygonal rod <NUM> includes a hexagonal portion 123B shaped like a hexagonal column. The hexagonal portion 123B of the polygonal rod <NUM> can be manually rotated to adjust the gaps between the brake pads <NUM> and the disc <NUM>.

A cylindrical screw shaft <NUM> is fixed to the second casing <NUM> and extends toward the first casing <NUM>. The screw shaft <NUM> has a cylindrical space 124A formed therein. The space 124A is open at the first casing <NUM> side only. The space 124A in the screw shaft <NUM> receives the polygonal rod <NUM>. The screw shaft <NUM> has external threads 124B on the outer surface thereof excluding the portion fixed to the second casing <NUM>. The screw shaft <NUM> is supported by a support spring 122A. The tip end portion of the screw shaft <NUM> has a hexagonal portion 124C shaped like a hexagonal column. The hexagonal portion 124C of the screw shaft <NUM> can be manually rotated to adjust the gaps between the brake pads <NUM> and the disc <NUM>. With the above arrangement, the gap adjustment is accessible from both sides of the gap adjuster <NUM>. The gaps thus can be adjusted by a large amount at one time, resulting in increased efficiency and ease of the adjustment during maintenance work.

An adjustment nut <NUM> shaped like a cylinder is provided on the outer periphery of the screw shaft <NUM>. The inner wall of the adjustment nut <NUM> partially has internal threads 125A that are configured to engage with the external threads 124B of the screw shaft <NUM>. The adjustment nut <NUM> rotates relative to the screw shaft <NUM> while engaging with the external threads 124B of the screw shaft <NUM>. Specifically, as the screw shaft <NUM> moves away from the polygonal rod <NUM>, the adjustment nut <NUM> is rotated by the external threads 124B of the screw shaft <NUM> and the internal threads 125A of the adjustment nut <NUM>.

The adjustment nut <NUM> is positioned between the extension portion 121A of the first casing <NUM> and the screw shaft <NUM>. The outer periphery of the adjustment nut <NUM> has a ridge 125B provided thereon. The ridge 125B projects toward the inner wall of the extension portion 121A of the first casing <NUM>. Between the adjustment nut <NUM> and the extension portion 121A of the first casing <NUM>, an anti-vibration spring <NUM> is provided and energizes the ridge 125B toward the first casing <NUM> in the axial direction of the adjustment nut <NUM>. The anti-vibration spring <NUM> is formed of a coil spring and is provided on the outer periphery of the adjustment nut <NUM>. Since the ridge 125B of the adjustment nut <NUM> is energized by the anti-vibration spring <NUM>, this can reduce the effect of vibration. A contact clutch <NUM> is provided between the adjustment nut <NUM> and the extension portion 121A of the first casing <NUM>. When the ridge 125B is pushed toward the left caliper lever <NUM> in the axial direction, the contact clutch <NUM> contacts the surface of the ridge 125B that is perpendicular to the axial direction to control rotation of the adjustment nut <NUM>. A cylindrical cover <NUM> covering the first casing <NUM> is fixedly attached to the second casing <NUM>.

A wire attachment portion <NUM> is attached to a portion of the screw shaft <NUM> near the first casing <NUM>. To the wire attachment portion <NUM>, the wire <NUM> is connected. A one-way clutch <NUM> is provided between the adjustment nut <NUM> and the extension portion 121A of the first casing <NUM>. The wire attachment portion <NUM> is fixedly attached to the one-way clutch <NUM>. The one-way clutch <NUM> and the wire attachment portion <NUM> can integrally rotate. The one-way clutch <NUM> permits the adjustment nut <NUM> to rotate such that the gap adjuster <NUM> is elongated but prevents the adjustment nut <NUM> from rotating such that the gap adjuster <NUM> is shortened. A spring <NUM> is attached to the one-way clutch <NUM>. If the wire <NUM> is pulled by the pulling unit <NUM>, the one-way clutch <NUM> and the wire attachment portion <NUM> rotate clockwise as seen from the left side, so that the spring <NUM> is compressed. If the wire <NUM> is released from being pulled, the energizing force from the spring <NUM> rotates the one-way clutch <NUM> and the wire attachment portion <NUM>, as well as the adjustment nut <NUM>, in a reversed direction (anti-clockwise), elongating the gap adjuster <NUM>.

Next, the operation of the brake caliper <NUM> will now be described. With additional reference to <FIG>, a description is given of the operation of the brake caliper <NUM> and the gap adjustment device <NUM> performed before the brake pads <NUM> are worn.

While the railway vehicle travels, the traveling causing the railway vehicle to vibrate and the vibration causes the wheels and bogies to move relative to each other in the width direction (the thickness direction of the disc <NUM>), the vertical direction and the front-rear direction of the railway vehicle. If the wheels and bogies move relative to each other, the body <NUM> supported on the bracket <NUM>, which is attached to the bogie, is prevented by the friction applying unit <NUM> from rotating around the coupling pin <NUM> relative to the bracket <NUM>. The friction applying unit <NUM> generates a frictional force at the contact surface between the body <NUM> and the second bracket 21B, and also generates a frictional force at the contact surface between the first bracket 21A and the body <NUM>. Accordingly, the body <NUM> hardly rotates relative to the bracket <NUM> even if the railway vehicle vibrates while traveling. Here, if the brake pads <NUM> are pushed by the disc <NUM> and the body <NUM> resultantly receives a force from the disc <NUM> via the left or right caliper lever <NUM> or <NUM>, the body <NUM> rotates around the coupling pin <NUM>. In other words, the friction applying unit <NUM> is configured such that it can prevent the body <NUM> from rotating around the coupling pin <NUM> when the vibration is generated, while allowing the body <NUM> to rotate around the coupling pin <NUM> when the disc <NUM> touches the brake pads <NUM>.

As shown in <FIG>, the brake caliper <NUM> is configured such that compressed air is fed into the first space <NUM> in the service brake cylinder <NUM> of the cylinder device <NUM> to actuate the service brake. The first rod <NUM> of the service brake cylinder <NUM> moves in such a direction that it projects from the first cylinder chamber <NUM> along with the first piston <NUM>, thereby driving the operation lever 35A clockwise via the roller 35B. Here, if the brake pads <NUM> have not worn off very much and the amount of movement (protrusion) of the first rod <NUM> is thus less than a predetermined value, the first rod <NUM> does not touch the pulling unit <NUM>.

As the first rod <NUM> moves in such a direction that it projects from the first cylinder chamber <NUM>, the operation lever 35A rotates clockwise along with the left rotation pin <NUM>. The clockwise rotation of the left rotation pin <NUM> causes the left caliper lever <NUM> to rotate about the rotational axis <NUM> in such a direction that the left brake pad <NUM> contacts the disc <NUM>, as a result of which the left brake pad <NUM> contacts the disc <NUM>.

After the left brake pad <NUM> contacts the disc <NUM>, the left caliper lever <NUM> rotates clockwise about the pad rotation pin <NUM>. When the left caliper lever <NUM> rotates about the pad rotation pin <NUM>, the right caliper lever <NUM> rotates counterclockwise about the right rotation pin <NUM> via the rotational axis <NUM>, the gap adjuster <NUM> and the rotational axis <NUM>, as a result of which the right brake pad <NUM> contacts the disc <NUM>.

When the compressed air is discharged from the second space <NUM> within the parking brake cylinder <NUM> and the second rod <NUM> projects from the second cylinder chamber <NUM>, the second rod <NUM> pushes the first piston <NUM> and the first rod <NUM>, resulting in the same operation as when the first rod <NUM> projects from the first cylinder chamber <NUM>.

The following now describes how the brake caliper <NUM> and the gap adjustment device <NUM> operate with the brake pads <NUM> having worn out. When the brake pads <NUM> are worn out, the service brake cylinder <NUM> operates in the same manner with compressed air fed thereto. The amount of movement of the first rod <NUM> increases as the amount of wear of the brake pads <NUM> increases. If the amount of wear of the brake pads <NUM> increases to such an extent that the amount of movement of the first rod <NUM> becomes equal to or greater than a predetermined value, the gap adjustment device <NUM> comes into operation. Specifically, the gap adjuster <NUM> is elongated to shorten the gaps between the brake pads <NUM> and the disc <NUM>.

If the first rod <NUM> has moved by a predetermined amount or more, the tip end portion of the first rod <NUM> touches the pulling unit <NUM> and the pulling unit <NUM> rotates, as a result of which the wire <NUM> is pulled. If the wire <NUM> is pulled, the wire attachment portion <NUM> rotates clockwise together with the one-way clutch <NUM>. Here, if the first rod <NUM> has moved by a predetermined amount or more, this means that the gaps between the brake pads <NUM> and the disc <NUM> are equal to or greater than a prescribed value.

Subsequently, in the brake caliper <NUM>, when the left brake pad <NUM> and the right brake pad <NUM> sandwich the disc <NUM> to generate a compressive force in the gap adjuster <NUM>, the screw shaft <NUM> tends to rotate the adjustment nut <NUM> in the direction for shortening. Here, the rotation of the adjustment nut <NUM> is controlled by the frictional force between the contact clutch <NUM> and the ridge 125B of the adjustment nut <NUM> and by the one-way clutch <NUM>. Therefore, the screw shaft <NUM> does not move in the direction for shortening, and the sandwiching force of the brake caliper <NUM> is maintained, thus generating a braking force.

Subsequently, in the brake caliper <NUM>, when feeding of the compressed air to the service brake cylinder <NUM> is stopped to release the brake, the first rod <NUM> returns to the first cylinder chamber <NUM>. This means that the first rod <NUM> no longer touches the pulling unit <NUM> and that the pulling unit <NUM> no longer pulls the wire <NUM>. If the wire <NUM> is released from being pulled, the energizing force from the spring <NUM> rotates the one-way clutch <NUM> and wire attachment portion <NUM>, as well as the adjustment nut <NUM>, in a reversed direction (anti-clockwise). Here, the one-way clutch <NUM> does not rotate in the direction for elongation. The one-way clutch <NUM> thus rotates anti-clockwise together with the adjustment nut <NUM>. This enlarges the entire length of the gap adjuster <NUM>, resulting in a larger distance between the base end portion of the left caliper lever <NUM> and the base end portion of the right caliper lever <NUM> and smaller gaps between the brake pads <NUM> and the disc <NUM>.

Advantageous effects of the first embodiment will be now described.

With reference to <FIG>, a second embodiment of the brake caliper will now be described. The second embodiment is different from the first embodiment in that the friction applying unit <NUM> of the brake caliper is arranged near the first end portion 22A of the coupling pin <NUM>. The following description will be focused on the differences from the first embodiment.

As shown in <FIG>, the friction applying unit <NUM> is enclosed within the first bracket 21A. The friction applying unit <NUM> is penetrated by the coupling pin <NUM> and configured to, as the body <NUM> and the first bracket 21A rotate relative to each other, generate sliding friction at the contact surface of the body <NUM> in the axial direction, surrounding the coupling pin <NUM>. The friction applying unit <NUM> serves as a rotation restraining unit for restraining the rotation of the coupling pin <NUM>. The friction applying unit <NUM> includes the friction ring <NUM>, which is a pressing member, for generating a frictional force when pressed against the body <NUM>. The friction ring <NUM> is penetrated by the coupling pin <NUM>. The friction applying unit <NUM> includes the spring <NUM>, which is an energizing member, for generating a frictional force by energizing the friction ring <NUM>. The spring <NUM> includes three disc springs. Alternatively, the spring <NUM> may include one, two or four or more disc springs, and the number of disc springs may be determined by a required energizing force. The spring <NUM> is penetrated by the coupling pin <NUM>.

The first end portion 22A of the coupling pin <NUM> has a smaller diameter than the second end portion 22B opposite the first end portion 22A. Accordingly, the coupling pin <NUM> is inserted into the body <NUM> from the side facing the second bracket 21B. The coupling pin <NUM> is then inserted into the first bracket 21A and fixedly secured by the bolt <NUM> with the first bracket 21A and the ring <NUM> being placed therebetween. The first bushing <NUM> is attached to the portion of the body <NUM> that touches the first bracket 21A. The second end portion 22B of the coupling pin <NUM> is press-fit into the second bracket 21B. The second busing <NUM> is attached to the portion of the body <NUM> that touches the second bracket 21B and the friction ring <NUM>. The first bushing <NUM> corresponds to a contact member.

As the spring <NUM> of the friction applying unit <NUM> energizes the body <NUM>, the first bracket 21A is energized in such a direction that the first bracket 21A separates away from the base portion <NUM> of the body <NUM>. As a result, the coupling pin <NUM>, as well as the first bracket 21A, is pulled toward the first bracket 21A, so that the second bracket 21B fixedly attached to the second end portion 22B of the coupling pin <NUM> is pressed against the base portion <NUM> of the body <NUM>. The friction applying unit <NUM> thus generates a frictional force at the contact surface between the body <NUM> and the first bracket 21A and also at the contact surface between the second bracket 21B and the body <NUM>. If the body <NUM> attempts to rotate relative to the bracket <NUM>, sliding friction is generated between the friction ring <NUM> and the first bushing <NUM>, thereby restraining the rotation.

Advantageous effects of the second embodiment will be now described. The following advantageous effects are obtained in addition to the advantageous effects (<NUM>) to (<NUM>) of the first embodiment.

(<NUM>) If the first bushing <NUM> is worn out, a desired frictional force can be restored by replacing the first bushing <NUM> with a new one. This facilitates the maintenance work when compared with the case where the body <NUM>, bracket <NUM> and coupling pin <NUM> are replaced with their counterparts.

(<NUM>) Since the first end portion 22A of the coupling pin <NUM> has a smaller diameter than the second end portion 22B, the weight can be reduced. As the spring <NUM> fittingly surrounds the outer periphery of the first end portion 22A, the spring <NUM> is allowed to have a smaller diameter than in a case where the spring <NUM> is provided around the second end portion 22B. The friction applying unit <NUM> can achieve a reduced size.

With reference to <FIG>, a third embodiment of the brake caliper will now be described. The third embodiment is different from the first embodiment in that the friction applying unit <NUM> is arranged between the body <NUM> and the coupling pin. The following description will be focused on the differences from the first embodiment.

As shown in <FIG>, a first coupling pin 222A is provided between the body <NUM> and the first bracket 21A. Between the body <NUM> and the second bracket 21B, a second coupling pin 222B is provided. The first and second coupling pins 222A and 222B constitute a coupling pin <NUM>. The brake caliper <NUM> includes the friction applying unit <NUM> for generating sliding friction at the contact surface of the second coupling pin 222B in the axial direction against the relative rotation between the body <NUM> and the second coupling pin 222B. The friction applying unit <NUM> is provided in the body <NUM>. The friction applying unit <NUM> generates sliding friction at the contact surface of the second coupling pin 222B that defines the second coupling pine 222B in the axial direction and that is on the axis. The friction applying unit <NUM> serves as a rotation restraining unit for restraining the rotation of the second coupling pin 222B. The friction applying unit <NUM> includes the friction ring <NUM>, which is a pressing member, for generating a frictional force when pressed against the second coupling pin 222B. The friction applying unit <NUM> includes the spring <NUM>, which is an energizing member, for generating a frictional force by energizing the friction ring <NUM>. The spring <NUM> includes three disc springs. Alternatively, the spring <NUM> may include one, two or four or more disc springs, and the number of disc springs may be determined by a required energizing force.

The first coupling pin 222A is inserted into the first bracket 21A and fixedly secured by the first bracket 21A and a bolt <NUM>. The second coupling pin 222B is inserted into the second bracket 21B and fixedly secured by a bolt <NUM> with the second bracket 21B and the ring <NUM> being placed therebetween. The first bushing <NUM> is attached to the portion of the body <NUM> that touches the first bracket 21A. The second bushing <NUM> is attached to the portion of the body <NUM> that touches the second bracket 21B.

Since the spring <NUM> of the friction applying unit <NUM> energizes the friction ring <NUM>, the friction ring <NUM> is pressed against the second coupling pin 222B. This can generate sliding friction between the friction ring <NUM> and the second coupling pin 222B. If the body <NUM> attempts to rotate relative to the second bracket 21B, the sliding friction is generated between the friction ring <NUM> and the second coupling pin 222B, thereby restraining the rotation.

Advantageous effects of the third embodiment will be now described. The following advantageous effects are obtained in addition to the advantageous effect (<NUM>) of the first embodiment.

(<NUM>) A frictional force is generated against the relative rotation between the body <NUM> and the second bracket 21B, thereby making it difficult for the body <NUM> to rotate relative to the second bracket 21B. This can prevent unintended contact between the brake pads <NUM> and the disc <NUM> when the brake is not in operation. In addition, since sliding friction is generated at the contact surface of the coupling pin <NUM> in the axial direction and prevents the rotation, friction can be applied in a more stabilized manner than in a case where friction is applied only at part of the contact surface of the coupling pin <NUM> in the axial direction.

With reference to <FIG>, a fourth embodiment of the brake caliper will now be described. The fourth embodiment is different from the third embodiment in that the friction applying unit <NUM> is arranged between the body <NUM> and a first coupling pin 222A. The following description will be focused on the differences from the third embodiment.

As shown in <FIG>, the brake caliper <NUM> includes the friction applying unit <NUM> for generating sliding friction at the contact surface of the first coupling pin 222A in the axial direction against the relative rotation between the body <NUM> and the first coupling pin 222A. The friction applying unit <NUM> is enclosed within the body <NUM>. The friction applying unit <NUM> generates sliding friction at the contact surface of the first coupling pin 222A that defines the first coupling pin 222A in the axial direction and that is on the axis. The friction applying unit <NUM> serves as a rotation restraining unit for restraining the rotation of the first coupling pin 222A. The friction applying unit <NUM> includes the friction ring <NUM>, which is a pressing member, for generating a frictional force when pressed against the first coupling pin 222A. The friction applying unit <NUM> includes the spring <NUM>, which is an energizing member, for generating a frictional force by energizing the friction ring <NUM>. The spring <NUM> includes three disc springs. Alternatively, the spring <NUM> may include one, two or four or more disc springs, and the number of disc springs may be determined by a required energizing force.

Since the spring <NUM> of the friction applying unit <NUM> energizes the friction ring <NUM>, the friction ring <NUM> is pressed against the first coupling pin 222A. This can generate sliding friction between the friction ring <NUM> and the first coupling pin 222A. If the body <NUM> attempts to rotate relative to the first bracket 21A, sliding friction is generated between the friction ring <NUM> and the first coupling pin 222A, thereby restraining the rotation.

Advantageous effects of the fourth embodiment will be now described. The following advantageous effects are obtained in addition to the advantageous effect (<NUM>) of the first embodiment.

(<NUM>) A frictional force is generated against the relative rotation between the body <NUM> and the first bracket 21A, thereby making it difficult for the body <NUM> to rotate relative to the first bracket 21A. This can prevent unintended contact between the brake pads <NUM> and the disc <NUM> when the brake is not in operation. In addition, since sliding friction is generated at the contact surface of the first coupling pin 222A in the axial direction and prevents the rotation, friction can be applied in a more stabilized manner than in a case where friction is applied only at part of the contact surface of the coupling pin <NUM> in the axial direction.

With reference to <FIG>, a fifth embodiment of the brake caliper will now be described. The fifth embodiment is different from the first embodiment in that the friction applying unit <NUM> is arranged between the coupling pin <NUM> and the second bracket 21B. The following description will be focused on the differences from the first embodiment.

As shown in <FIG>, the brake caliper <NUM> includes the friction applying unit <NUM> for generating sliding friction at the contact surface of the coupling pin <NUM> in the axial direction against the relative rotation between the coupling pin <NUM> and the second bracket 21B. The friction applying unit <NUM> is enclosed within the second bracket 21B. The friction applying unit <NUM> generates sliding friction at the contact surface of the coupling pin <NUM> that defines the coupling pin <NUM> in the axial direction and that is on the axis. The friction applying unit <NUM> serves as a rotation restraining unit for restraining the rotation of the coupling pin <NUM>. The friction applying unit <NUM> includes the friction ring <NUM>, which is a pressing member, for generating a frictional force when pressed against the coupling pin <NUM>. The friction applying unit <NUM> includes a spring <NUM>, which is an energizing member, for generating a frictional force by energizing the friction ring <NUM>. The spring <NUM> includes three disc springs. Alternatively, the spring <NUM> may include one, two or four or more disc springs, and the number of disc springs may be determined by a required energizing force.

The first end portion 22A of the coupling pin <NUM> has a greater diameter than the second end portion 22B opposite the first end portion 22A. Accordingly, the coupling pin <NUM> is inserted into the body <NUM> from the side facing the first bracket 21A. The first end portion 22A of the coupling pin <NUM> is press-fit into the first bracket 21A. The second end portion 22B of the coupling pin <NUM> is press-fit into the second bracket 21B. In other words, after the spring <NUM> and the friction ring <NUM> are inserted into the second bracket 21B, the second end portion 22B of the coupling pin <NUM> is press-fit into the second bracket 21B. In this way, the friction applying unit <NUM> is completed. The coupling pin <NUM> is fixedly attached to the body <NUM>. Accordingly, as the body <NUM> rotates relative to the second bracket 21B, sliding friction is generated between the second end portion 22B of the coupling pin <NUM> and the second bracket 21B.

Advantageous effects of the fifth embodiment will be now described. The following advantageous effects are obtained in addition to the advantageous effects (<NUM>) and (<NUM>) of the first embodiment.

(<NUM>) A frictional force is generated against the relative rotation between the coupling pin <NUM> and the second bracket 21B, thereby making it difficult for the coupling pin <NUM> to rotate relative to the second bracket 21B. This can prevent unintended contact between the brake pads <NUM> and the disc <NUM> while the brake is not in operation. In addition, since sliding friction is generated at the contact surface of the coupling pin <NUM> in the axial direction and prevents the rotation, friction can be applied in a more stabilized manner than in a case where friction is applied only at part of the contact surface of the coupling pin <NUM> in the axial direction.

With reference to <FIG>, a sixth embodiment of the brake caliper will now be described. The sixth embodiment is different from the fifth embodiment in that the friction applying unit <NUM> is arranged between the coupling pin <NUM> and the first bracket 21B. The following description will be focused on the differences from the fifth embodiment.

As shown in <FIG>, the brake caliper <NUM> includes the friction applying unit <NUM> for generating sliding friction at the contact surface of the coupling pin <NUM> in the axial direction against the relative rotation between the coupling pin <NUM> and the first bracket 21A. The friction applying unit <NUM> is enclosed within the first bracket 21A. The friction applying unit <NUM> generates sliding friction at the contact surface of the coupling pin <NUM> that defines the coupling pin <NUM> in the axial direction and that is on the axis. The friction applying unit <NUM> serves as a rotation restraining unit for restraining the rotation of the coupling pin <NUM>. The friction applying unit <NUM> includes the friction ring <NUM>, which is a pressing member, for generating a frictional force when pressed against the coupling pin <NUM>. The friction applying unit <NUM> includes the spring <NUM>, which is an energizing member, for generating a frictional force by energizing the friction ring <NUM>. The spring <NUM> includes three disc springs. Alternatively, the spring <NUM> may include one, two or four or more disc springs, and the number of disc springs may be determined by a required energizing force.

The first end portion 22A of the coupling pin <NUM> has a greater diameter than the second end portion 22B opposite the first end portion 22A. Accordingly, the coupling pin <NUM> is inserted into the body <NUM> from the side facing the first bracket 21A. The first end portion 22A of the coupling pin <NUM> is press-fit into the first bracket 21A. The second end portion 22B of the coupling pin <NUM> is press-fit into the second bracket 21B. In other words, after the spring <NUM> and the friction ring <NUM> are inserted into the first bracket 21A, the first end portion 22A of the coupling pin <NUM> is press-fit into the first bracket 21A. In this way, the friction applying unit <NUM> is completed. The coupling pin <NUM> is fixedly attached to the body <NUM>. Accordingly, as the body <NUM> rotates relative to the first bracket 21A, sliding friction is generated between the first end portion 22A of the coupling pin <NUM> and the first bracket 21A.

Advantageous effects of the sixth embodiment will be now described. The following advantageous effects are obtained in addition to the advantageous effects (<NUM>) and (<NUM>) of the first embodiment.

(<NUM>) A frictional force is generated against the relative rotation between the coupling pin <NUM> and the first bracket 21A, thereby making it difficult for the coupling pin <NUM> to rotate relative to the first bracket 21A. This can prevent unintended contact between the brake pads <NUM> and the disc <NUM> when the brake is not in operation. In addition, since sliding friction is generated at the contact surface of the coupling pin <NUM> in the axial direction and prevents the rotation, friction can be applied in a more stabilized manner than in a case where friction is applied only at part of the contact surface of the coupling pin <NUM> in the axial direction.

The foregoing embodiments can be modified as described below. The above embodiments and the following modifications can be implemented in combination to the extent where they are technically consistent with each other.

In the first, second, fifth and sixth embodiments, the first and second end portions 22A and 22B of the coupling pin <NUM> have different diameters. The first and second end portions 22A and 22B of the coupling pin <NUM>, however, may have the same diameter.

In the first to fourth embodiments, the bolts <NUM> are used to fixedly secure the coupling pin <NUM>, <NUM> onto the bracket <NUM>. The bolts <NUM>, however, may not be used as long as the coupling pin <NUM>, <NUM> can be fixedly secured onto the bracket <NUM>.

In the foregoing embodiments, the first bushing <NUM> is provided. The embodiments of the present invention, however, may be practiced without the first bushing <NUM>. In the foregoing embodiments, the second bushing <NUM> is provided. The embodiments of the present invention, however, may be practiced without the second bushing <NUM>.

Although the energizing member or spring <NUM> is formed by the disc springs in the above-described embodiments, other structures or mechanisms may be used instead of the disc springs as long as they can push the pressing member or friction ring <NUM>. For instance, the energizing member may be formed of a different type of springs such as a coil spring or an elastic member such as an O-ring. As a further alternative example, the energizing member may be constituted by a first permanent magnet and a second permanent magnet that is attached to the pressing member. Here, the first and second permanent magnets are arranged such that like poles of the first and second permanent magnets face each other. In this case, the pressing member is pushed by a repulsive force generated between the first permanent magnet and the second permanent magnet.

The foregoing embodiments may be practiced without the energizing member. The foregoing embodiments employ the cylinder device <NUM> as the actuator, but may use other devices such as motor devices as the actuator.

Claim 1:
A brake caliper (<NUM>) comprising:
a pair of caliper levers (<NUM>, <NUM>), each caliper lever (<NUM>, <NUM>) retaining a brake pad (<NUM>);
an actuator (<NUM>) for outputting a force to rotate the caliper levers (<NUM>, <NUM>) such that the caliper levers (<NUM>, <NUM>) press a disc (<NUM>);
a body (<NUM>) retaining the caliper levers (<NUM>, <NUM>) in a rotatable manner and retaining the actuator (<NUM>);
a bracket (<NUM>) fixedly attached to a bogie; and
a coupling pin (<NUM>) coupling the body (<NUM>) to the bracket (<NUM>) such that the body (<NUM>) and the bracket (<NUM>) are rotatable relative to each other around a rotational axis extending in a longitudinal direction of the caliper levers (<NUM>, <NUM>);
characterized in that the brake caliper (<NUM>) comprises a friction applying unit (<NUM>) penetrated by the coupling pin (<NUM>), the friction applying unit (<NUM>) being configured to restrain rotation of the body (<NUM>) by generating sliding friction at a contact surface of the friction applying unit (<NUM>) where the friction applying unit (<NUM>) touches the body (<NUM>) or the bracket (<NUM>).