Floating brake caliper with a body partially made of plastic material

Abstract

A brake caliper (10) comprises a stationary metal support portion (14) attachable to a two-wheeled vehicle, two brake pads (12, 13) with associated support plates (12b, 13b) having at least one side surface (18a, 18b) extending, in use, in a substantially radial direction relative to a rotation axis of a wheel of the vehicle. A sliding block (15) comprises two metal end plates (21, 22) between which a rigid body (24) made of plastic material is arranged and locked. The stationary support portion (14) has an abutment surface (25) facing one (18a) of the side surfaces (18a, 18b) of each support plate (12b, 13b). The plastic block forms a recess (27) that accommodates the brake pads and allows the brake pads to achieve a stable contact position against the contact surface of the stationary support area during braking.

Description

Technical area

[0001] The present invention relates to a floating brake caliper partially made of a plastic material. The present brake caliper is particularly, but not exclusively, applicable to two-wheeled vehicles, such as bicycles. State of the art

[0002] Floating brake calipers for two-wheeled vehicles typically comprise a stationary support portion fixed to the vehicle and a sliding block that can slide relative to the support portion and the brake disc along a direction parallel to the rotational axis of the brake disc. The sliding block has a C-shaped overall configuration and includes a bridge portion, to each of whose distal ends is connected a lateral portion extending transversely to the bridge portion. This geometry allows the sliding block to span the brake disc, with the lateral portions facing the braking surfaces of the brake disc. One side of the lateral portion, facing the brake disc, is usually configured to house a cylinder or piston.A brake pad is positioned between the piston and the braking surface of the brake disc. During braking, the pad is pressed toward the brake disc by the piston to generate braking force. The loads generated during braking are primarily transferred from the pads to the sliding block.

[0003] As is well known, the sliding block of a brake caliper for two-wheeled vehicles is made of a metallic material, typically aluminum or steel, with the goal of withstanding the loads it is subjected to during braking and transferring these loads to the vehicle structure. The manufacturing costs of these sliding blocks are high due to the choice of materials and the manufacturing process.

[0004] US 2022 / 0381304 A1 discloses a brake caliper comprising two brake pads, a stationary support portion mountable on the vehicle, and a block axially movable relative to the stationary portion. The brake pads are axially movable and can be arranged to face two opposing braking surfaces of the brake disc, each brake pad having a support plate with at least one side surface extending, in use, in a substantially radial direction relative to a rotational axis of a vehicle wheel.

[0005] Conventionally, the sliding block consists of a single monolithic metal body having a substantially C-shaped overall shape, with two lateral wings connected by a connecting area; between the lateral wings and the connecting area there is an empty space to allow the passage of a peripheral part of a rotating brake disc and to accommodate the two brake pads in an area axially extending between the lateral wings. Overview of the invention

[0006] A primary objective of the present invention is to provide a lightweight brake caliper. Another objective of the present invention is to provide an economical brake caliper. Another scope of the invention is to provide a brake caliper that can efficiently transfer thermal loads to the environment and braking loads to the vehicle structure.

[0007] The above and other objects and advantages, which will be explained in more detail below, are achieved by a brake caliper having the features recited in independent claim 1. Preferred embodiments of the invention are recited in the dependent claims.

[0008] Briefly, a floating brake caliper for two-wheeled vehicles comprises one or more pistons, two brake pads, each comprising a support plate having at least one side extending in the direction of a rotation axis of a wheel, a stationary support portion fixed to the vehicle and comprising an abutment surface facing one of the sides of each support plate, and a sliding block axially movable with respect to the stationary portion and arranged in a bridge, being mounted on a brake disc in use. The sliding block comprises first and second end plates and a connecting element for the end plates made of metal material. The sliding block further comprises a rigid body made of plastic material, arranged and locked between the end plates and having a recess for accommodating the brake pads.The recess in the rigid plastic body allows the brake pads to reach a stable stopping position against the contact surface of the stationary carrier area during braking. Short description of the drawings

[0009] The features and advantages of the present invention will become apparent from the following description, which is given as a non-limiting example. Reference is made to the accompanying drawings, in which: Fig. Figure 1 is a perspective view of an embodiment of a brake caliper according to the invention; Fig. 2 a perspective view of the brake caliper from Fig. 1 from a different perspective; Fig. 3 an exploded perspective view of the brake caliper from Fig. 1 is; Fig. 4 an exploded perspective view of some of the Fig. 3 components shown; Fig. Figure 5 is an exploded perspective view of a block forming part of the brake caliper; Fig. 6 a perspective view of the block from Fig. 5 is in an assembled state; Fig. Figure 7 is a perspective view of a stationary portion of the carrier forming part of the brake caliper; Fig. 8 is a perspective view of a state in which a radially extending side of a brake pad abuts against an abutment surface of the stationary support portion of the brake caliper during braking; Fig. 9 a perspective view of the Fig. 8, shown with the stationary area in partial transparency to show some hidden parts; Fig. Figure 10 is a perspective view of a rigid plastic body forming part of the brake caliper; Fig. 11 a perspective view of the rigid body in Fig. 9 from a different perspective; Fig. 12 a longitudinal cross-sectional view of the brake caliper in Fig. 1 is; Fig. 13 a cross-sectional view of the brake caliper in Fig. 1 is; Fig. 14 is a cross-sectional view of an alternative embodiment of a brake caliper according to the invention; Fig. 15 is a perspective view of a brake caliper coupled to a vehicle frame and spanning a brake disc; and Fig. 16 a perspective view from a different angle of the brake calliper, frame and brake disc from Fig. 15 is. Detailed description

[0010] With reference to the Fig. 1 to 3, a brake caliper according to an embodiment of the invention is described. A brake caliper for two-wheeled vehicles is indicated overall by 10. The brake caliper typically has a C-shaped overall form, such that it can be mounted in a known manner in a bridge-like or overlapping manner over a brake disc (visible in the Fig. 12, Fig. 13) can be ordered.

[0011] The brake calliper 10 defines a transverse axis x ( Fig. 1-3), which is parallel to the axis of rotation of the brake disc. In the present description and the claims, terms and expressions indicating positions, directions and orientations, such as "axial" and "transverse", refer to an axis that, in the assembled state, is parallel to the axis of rotation of the wheel with which the brake caliper is associated. The term "longitudinal" is to be understood as referring to a direction orthogonal to the direction defined here as transverse and parallel to the direction of travel of the vehicle. The term "radial", on the other hand, is to be understood as referring to an axis of rotation of the brake disc and thus to directions that are radial to the transverse axis x and lie in vertical planes orthogonal to the transverse axis x. The term "tangential" is to be understood with respect to the rotation of the brake disc.

[0012] The brake calliper 10 comprises at least one piston 11, two brake pads 12, 13, a stationary support portion 14 and a sliding block 15 ( Fig. 3), which is located transversely to the stationary support area 14.

[0013] The piston 11 is typically cylindrically shaped and has a cylindrical lateral surface 16 and a longitudinal base surface 17.

[0014] According to one embodiment, the piston 11 is made of plastic material, for example phenolic resins (PF).

[0015] The brake pads 12, 13 are arranged on opposite sides of the brake disc and are axially movable along the transverse axis x.

[0016] The structural and functional characteristics of a floating-type brake caliper are known and therefore will not be described in detail here. It should simply be recalled that, during braking, the supply of pressurized fluid to a hydraulic chamber inside the caliper pushes one or more pistons transversely against a first brake pad and toward a first side of the brake disc. Once a first brake pad has made contact with the brake disc, the pressure of the piston forces the sliding block to move orthogonally to the plane of the brake disc, bringing a second brake pad into contact with a second side of the brake disc, opposite the first side.

[0017] Each brake pad 12, 13 comprises a carrier plate 12b, 13b, to one side of which a respective layer 12a, 13a of friction material is securely applied so as to face, in use, the respective one of the two opposing braking surfaces of the brake disc. The friction material may typically be a sintered material. In order to withstand the loads occurring during braking, the carrier plates 12b, 13b are typically made of a metallic material, such as iron and its alloys. As is known, the actuation of the piston 11 brings the friction materials 12a, 13a into contact with the braking surfaces of the brake disc during braking. The brake pads described and illustrated herein may be of conventional design.

[0018] The carrier plate 13b has an engagement surface 13c ( Fig. 3) which can be engaged by the piston 11 in order to absorb a transverse axial thrust from it during the braking process.

[0019] In addition, the carrier plates 12b, 13b of the brake pads 12, 13 each have a pair of opposite side surfaces 18a, 18b ( Fig. 3, Fig. 8, Fig. 9) lying in two respective transverse planes oriented, when mounted on the vehicle, in substantially radial directions toward the wheel's rotational axis. Each side surface 18a, 18b of the support plates 12b, 13b defines a respective radially extending or elongated lateral surface having a radial dimension greater than an axial dimension.

[0020] According to one embodiment, the stationary support portion 14 has a generally elongated shape in a longitudinal direction ( Fig. 2), or in a tangential direction, taking into account the condition of the caliper in use, mounted on a vehicle, with respect to the direction of rotation of the brake disc. The stationary portion 14 can be considered a spacer or adapter that can be manufactured in various sizes and shapes to fit the brake caliper and thus adapt to different vehicles.

[0021] The stationary area 14 can have two holes 19, 20 ( Fig. 7) or other means or mounting seats that allow the stationary support area 14, and thus the brake calliper 10, to be fixed to the vehicle chassis.

[0022] Preferably, the stationary support portion 14 is made of metal material, such as aluminum or steel, to ensure a firm and stable attachment to the vehicle.

[0023] In a floating brake caliper 10, the sliding block 15 can slide with respect to the stationary portion 14 in the axial direction, ie along a direction parallel to the transverse axis x.

[0024] The sliding block 15 is axially displaceable toward the stationary portion 14 and is configured to span a peripheral portion of a rotating brake disc in use ( Fig. 15, Fig. 16).

[0025] As in Fig. As shown in Figure 6, the sliding block 15 has a substantially C-shaped overall configuration, with two axially spaced lateral wings 15a, 15b connected by a connecting portion 15c. A space or gap 15d is identified between the lateral wings 15a, 15b and the connecting portion 15c. The space 15d accommodates the two brake pads 12, 13 between the lateral wings 15a, 15b and, in use, allows the passage of a peripheral portion of the brake disc between the brake pads.

[0026] The lateral wings 15a, 15b, the connecting area 15c and the gap 15d of the sliding block 15 are formed by several components assembled together: two opposite end plates 21, 22, a connecting element 23 and a plastic body 24 which is clamped between the end plates 21, 22.

[0027] As in the Fig. 5 and Fig. 6, the sliding block 15 comprises two opposite end plates 21, 22, which are axially spaced from one another and arranged at respective axially or transversely opposite ends of the sliding block 15: a first end plate 21 and a second end plate 22. The sliding block 15 further comprises an axial or transverse connecting element 23 which rigidly connects the two end plates 21, 22, and a body 24 made of plastic material which is arranged between the first end plate 21 and the second end plate 22 and is firmly locked by the connecting element 23.

[0028] The end plates 21, 22 and the connecting element 23 are made of a metal material, preferably steel.

[0029] The end plates 21, 22 extend in respective geometric planes orthogonal to the transverse axis x and are transversely spaced apart. The connecting element 23 extends axially to rigidly connect the end plates 21, 22. The end plates 21, 22 are axially spaced apart such that, in the assembled state, they lie on opposite sides of the brake disc.

[0030] Advantageously, the connecting element 23 can be designed as a transversely extended pin or rod, which, in addition to the structural function of connecting the end plates 21, 22, can also serve for mounting the brake pads 12, 13. For this purpose, the support plates 12b, 13b can each have a through hole 12d, 13d ( Fig. 3) into which the connecting pin 23 can be inserted.

[0031] The sliding block 15 further comprises a rigid body 24 made of plastic material, which is arranged and locked between the first end plate 21 and the second end plate 22 by the connecting element 23.

[0032] The operation of a floating brake caliper is generally considered known; therefore, in the following part of this description, only the elements relevant to the implementation of the floating brake caliper according to the invention are described. For the implementation of parts and elements not shown in detail, such as hydraulic connections, reference can be made to any solution relating to a floating brake caliper of known design.

[0033] The stationary area 14 of the brake calliper 10 comprises at least one contact surface 25 ( Fig. 7) which is manufactured in such a way that it corresponds to one (the side surface 18a) of the two side surfaces 18a, 18b of each support plate 12b, 13b ( Fig. 8 and Fig. 9) is facing.

[0034] The contact surfaces 25 and the side surface 18a of each support plate 12b, 13b may be flat. Alternative embodiments (not shown) may provide for the contact surfaces 25 of the stationary support portion 14 and the side surface 18a of each support plate 12b, 13b to have corresponding, at least partially matching shapes to form an expanded contact surface for more efficient transmission of braking loads. For example, the surfaces 25a and 18a may have a corresponding and matching curvature.

[0035] The contact surface 25 can be formed by a protruding area 26 ( Fig. 8) of the stationary support area 14.

[0036] In an alternative embodiment, the stationary portion 14 may be formed as a monoblock with a single contact surface 25. In an alternative embodiment, the contact surface 25 may comprise at least two separate and / or parallel surfaces. In a further embodiment, not shown, the contact surface 25 may be maintained on an element formed separately from the stationary portion 14 and fixedly attached thereto by means of a mechanical fastening means, such as a screw or bolt, or by locking. Other embodiments may provide for the stationary portion 14 to be formed as a single part with the bicycle fork.

[0037] The rigid body 24 made of plastic material has a recess 27 that forms the space or gap 15d between the lateral wings 15a, 15b to accommodate the brake pads and, during use, allows the passage of a peripheral portion of the brake disc between the pads. The recess 27 is configured such that the side 18a of each support plate 12b, 13b can achieve a stable bearing position against the bearing surface 25 of the stationary support portion 14 during braking.

[0038] Since the rigid body 24 is made of plastic, it can advantageously be manufactured by injection molding using materials such as polyamide (PA66). In particular, polyamide reinforced with glass or carbon fibers in varying proportions, e.g., 30% or 50% (PA66GF30, PA66GF50), can be used.

[0039] According to one embodiment, the rigid body 24 may have an overall L-shaped form comprising an upper part 28 (or radially outer) part and a lateral part 29 ( Fig. 7 and Fig. 8).

[0040] The upper part 28 of the rigid body 24 may extend in a substantially axial direction and have a curved shape to correspond to the shape of the support plates 12b, 13b of the brake pads 12, 13.

[0041] Furthermore, the upper part 28 may be provided as a bridge formation that allows the first end plate 21 and the second end plate 22 to be connected on opposite sides of the rigid body 24.

[0042] The lateral part 29 ( Fig. 1) of the rigid body 24 can be formed in the longitudinal direction and have at least two through holes 30, 31 ( Fig. 10) that are spaced apart and arranged opposite one another with respect to the transverse axis x. Preferably, the two holes 30, 31 can be parallel to the transverse axis x.

[0043] As in Fig. As shown in Figure 12, the brake caliper 10 may also include two pins 32, 33 fixed and integral with the stationary support portion 14. The pins 32, 33 may pass through the two holes 30, 31 formed through the lateral portion 29 of the rigid body 24, thus guiding the axial movement of the sliding block 15 relative to the stationary support portion 14 during braking.

[0044] The pins 32, 33 may be horizontally oriented, ie they may be substantially parallel to the transverse axis x, and spring elements 32a, 33a may be arranged between them and the rigid body 24.

[0045] The rigid body 24, which is arranged and locked between the first plate 21 and the second plate 22 by the connecting element 23, remains integrally connected thereto.

[0046] The rigid body 24 has an inner surface 34 facing the piston 11 and the brake pads 12, 13, and an outer surface 35 opposite the inner surface 34 ( Fig. 10 and Fig. 11). The outer surface 35 may have an outer recess 36, and the inner surface 34 may have an inner cylindrical cavity 37.

[0047] Preferably, the rigid body 24 forms an axial passage 38 extending from the outer surface 35 to the inner surface 34. In particular, the passage 38 connects the outer surface 35 to the inner cylindrical cavity 37.

[0048] Manufacturing the rigid body 24 from plastic by injection molding is particularly advantageous for obtaining a one-piece, lightweight rigid body. Furthermore, manufacturing by casting is advantageous in terms of time and machining costs, allowing the brake caliper to be manufactured more economically. In fact, this technology allows the rigid body 24 to form the outer recess 36, the cylindrical cavity 37, and the passage 38 in a single step, without requiring subsequent steps and without the need to remove any material.

[0049] The outer recess 36 on the outer surface 35 of the rigid body 24 may be configured to accommodate the first plate 21 ( Fig. 3). In particular, the outer recess 36 may have a shape corresponding to a contour 21a or edge of the first plate 21 to accommodate and lock the first plate 21, thereby preventing its relative movement with respect to the rigid body 24.

[0050] The inner cylindrical cavity 37 on the inner surface 34 of the rigid body 24 may have a cylindrical side wall 39 and a base wall 40 ( Fig. 10). The inner cylindrical cavity 37 is configured to at least partially accommodate the piston 11 and to form a hydraulic chamber 41 therewith for receiving and actuating the piston 11. In particular, the inner cylindrical cavity 37 can have a diameter that substantially corresponds to a diameter of the piston 11.

[0051] The passage 38 may be provided through the lateral part 29 of the rigid body 24 coaxially with the transverse axis x. The passage 38 is preferably cylindrical, such that it accommodates at least one hydraulic connector 42 and brings an inlet channel 43 into fluid communication with the hydraulic chamber 41 ( Fig. 13).

[0052] During braking, brake fluid flows from the inlet channel 43 into the hydraulic chamber 41, expanding it and thereby actuating the floating brake caliper 10. Specifically, during braking, the piston 11 is pushed axially toward the brake pad 13, which approaches a braking surface of the brake disc. As a result of the pressure of the brake fluid in the hydraulic chamber, the rigid body 24 and the first end plate 21 move in an axial direction opposite to the piston, thereby pushing the second end plate 22 and the brake pad 12 toward a second surface of the brake disc, opposite to the first.

[0053] The brake pad 10 may further comprise at least one annular elastic sealing element 44 ( Fig. 12 and Fig. 13), typically having a rectangular or square cross-sectional area, which can provide a sliding contact seal between the cylindrical surface 16 of the piston 11 and the cylindrical wall 39 of the inner cylindrical cavity 37 of the rigid body 24.

[0054] In a preferred embodiment ( Fig. 13), the annular sealing element 44 is partially housed in a groove 45 made in the cylindrical surface 16 of the piston 11. In such an embodiment, the elastic annular sealing element 44 acts in sliding contact against the cylindrical wall 39 of the inner cylindrical cavity 37 of the rigid body 24. This embodiment is particularly advantageous when the rigid body 24 is obtained by a casting process, since the cylindrical surface 39 of the inner cylindrical cavity 37 of the rigid body can be made smooth and free of undercuts, without requiring additional machining of the component and using a casting mold with a simplified shape.

[0055] The sealing element 44 can be mounted in a radially compressed state between the groove 45 on the piston 11 and the cylindrical wall 39 of the rigid body 24. During braking, the sealing element 44 is elastically deformed in the axial direction due to the relative axial movement of the piston 11 and the rigid body 24 in opposite directions. After the braking action is terminated, the elastic element 44 returns to its undeformed state and pushes the piston 11 away from the brake pad 13, which in turn is pushed away from the braking surface of the brake disc by a spring 46. Simultaneously, the rigid body 24 and the first plate 21 are moved in an axial direction opposite to the piston 11, thereby pushing the second plate 22 away from the brake pad 12, which in turn is pushed away from the braking surface of the brake disc by the spring 46.This pushing away of the brake pads 12, 13 from the brake disc can advantageously be reinforced by a release effect of the spring elements 32a, 33a mounted between the pins 32, 33 and the rigid body 24.

[0056] In an alternative embodiment ( Fig. 14), the groove 45 accommodating the annular elastic sealing element 44 may be formed on the cylindrical wall 39 of the inner cylindrical cavity 37 of the rigid body 24. In such an embodiment, the sealing elements may act against the cylindrical surface 16 of the piston 11.

[0057] In one embodiment, the brake caliper 10 can be mounted on a frame 51 ( Fig. 15 and Fig.16) of a two-wheeled vehicle and arranged so that it spans a brake disc 50 such that the friction material layer 12a, 13a of the brake pads 12, 13 each faces one of the two opposite braking surfaces of the brake disc 50.

[0058] As can be seen, it is advantageous that the contact surface 25 for the brake pads is provided by the metallic stationary portion of the carrier 14, which is rigidly fixed (or integral) to the fork, rather than by the caliper body as in conventional non-floating calipers. In this floating caliper, the caliper body is loaded only by the hydraulic pressure exerted on the disc by the compression force of the brake pads, and not by the transmission of braking torque to the fork.

[0059] Although specific embodiments of the invention have been disclosed, it is to be understood that this disclosure is provided for illustrative purposes only and that the invention is in no way limited thereby. Various modifications will be apparent to those skilled in the art in light of the above examples. The scope of the invention is limited only by the appended claims. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] US 2022 / 0381304 A1

[0004]

Claims

[1] Brake calliper (10) for two-wheeled vehicles, the calliper defining a transverse axis (x) and comprising: two brake pads (12, 13) which are axially movable and can be arranged, in use, facing two opposite brake disc braking surfaces, each brake pad (12, 13) having a carrier plate (12b, 13b) with at least one side surface (18a, 18b) which, in use, extends in a substantially radial direction to an axis of rotation of a vehicle wheel; a stationary support portion (14) made of metal material and attachable to or integral with a two-wheeled vehicle, the stationary support portion (14) comprising at least one abutment surface (25) facing, in use, one (18a) of the side surfaces (18a, 18b) of each support plate (12b, 13b); a sliding block (15) axially displaceable with respect to the stationary support portion (14), the sliding block being configured, in use, to be arranged to straddle a brake disc, the sliding block (15) having a substantially C-shaped overall configuration with two lateral wings (15a, 15b) connected by a connecting portion (15c) to a space (15d) defined between the two lateral wings (15a, 15b) and the connecting portion (15c), the space accommodating the two brake pads (12, 13) between the lateral wings (15a, 15b) and allowing the passage of a peripheral portion of the brake disc between the brake pads; characterized by that the sliding block (15) comprises: - a first metal end plate (21) and a second metal end plate (22), each forming one of the axially spaced lateral wings (15a, 15b) arranged on opposite sides of the brake disc in use; - a metal connecting element (23) rigidly connecting the first end plate (21) and the second end plate (22); and - a rigid body (24) made of a plastic material, arranged and locked between the first end plate (21) and the second end plate (22) and forming a recess (27) providing the space (15d) in which the two brake pads (12, 13) are housed; wherein the lateral side (18a) of each support plate (12b, 13b) has a bearing position against the bearing surface (25) of the stationary region (14) through the recess (27) of the rigid body (24) during the braking operation. [2] Brake caliper (10) according to claim 1, wherein the rigid body (24) has an outer surface (35), an inner surface (34) opposite the outer surface (35) and facing the piston (11), at least one inner cylindrical cavity (37) formed in the inner surface (34) for partially accommodating at least one corresponding piston (11) and for defining a hydraulic chamber (41) therein, and an axial passage (38) extending between the inner cylindrical cavity (37) and the outer surface (35) for establishing fluid communication between the hydraulic chamber (41) and a hydraulic connector (42) for conveying brake fluid to the brake caliper. [3] Brake caliper (10) according to claim 1 or 2, wherein the rigid body (24) has an outer surface (35), an inner surface (34) opposite the outer surface (35) and facing the piston (11), and an outer recess (36) formed in the outer surface (35) of the rigid body (24) and configured to accommodate the first end plate (21). [4] Brake caliper (10) according to claim 3, wherein the outer recess (36) of the rigid body (24) has a shape corresponding to a contour (21a) of the first end plate (21) to accommodate and lock the first end plate (21), thereby preventing its relative movement with respect to the rigid body (24). [5] Brake caliper (10) according to claim 2, comprising at least one resilient annular sealing element (44) mounted in a groove (45) formed in a cylindrical surface (16) of the piston (11) and acting in sliding contact against the cylindrical wall (39) of the inner cylindrical cavity (37). [6] Brake caliper (10) according to claim 1, wherein the caliper further comprises at least two axially elongated pins (32, 33) fixed to and integral with the stationary support portion (14) and configured to guide axial movement of the sliding block (15) relative to the stationary support portion (14). [7] Brake caliper (10) according to one of the preceding claims, wherein the connecting element (23) is an axially elongated pin connecting the first end plate (21) to the second end plate (22). [8] Brake caliper (10) according to one of the preceding claims, wherein the stationary support portion (14) is formed as a single piece integral with a fork of the two-wheeled vehicle.

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