Engine brake arm buffer mechanism

Abstract

A buffer mechanism for an engine braking rocker arm includes an elastic body disposed between the rocker arm and the rocker arm shaft. The elastic body abuts against both the rocker arm and the rocker arm shaft, and its elastic deformation applies a force between the rocker arm and the rocker arm shaft. This creates a resistance to the rocker arm's movement on the rocker arm shaft, keeping the rocker arm in a non-collision position. In this non-collision position, one end of the rocker arm avoids the drive of the engine camshaft, and the other end avoids interaction with the engine valves. In this embodiment, the rocker arm does not move during engine ignition, eliminating mechanism slippage, friction, and oil consumption, significantly reducing usage frequency.

Description

Technical Field:

[0001] This embodiment relates to the field of mechanics, and more particularly to engines, and especially to a buffer mechanism for an engine brake rocker arm. Background technology:

[0002] Cummins Engine Company disclosed a dedicated brake rocker arm in U.S. Patent No. 5,626,116 (1997). The dedicated brake rocker arm houses a hydraulic brake drive mechanism, including a hydraulic piston. When engine braking is not required, the hydraulic piston in the dedicated brake rocker arm is in the retracted position, the dedicated brake rocker arm is separated from the valve, and the movement of the dedicated brake cam is skipped (lost), resulting in no braking valve movement. When engine braking is required, the hydraulic piston in the dedicated rocker arm is in the extended position, and the dedicated rocker arm transmits the movement of the dedicated brake cam to one of the two exhaust valves, generating the valve movement for engine braking.

[0003] US Patent 5,975,251 (1999) discloses a locking device for a dedicated brake rocker arm. In the non-braking (ignition) state, the dedicated brake rocker arm is locked to the rocker arm shaft, with both ends suspended, neither contacting the brake cam nor the brake valve. This locking device was used on the dedicated brake rocker arm of the Cummins ISX engine, but it was found to be unreliable. The rocker arm would swing back and forth on the rocker arm shaft and impact, causing engine damage. Clearly, during braking, the rocker arm can rotate freely on the rocker arm shaft and cannot be positioned, potentially leading to collisions with the cam or valve, resulting in poor reliability.

[0004] Existing dedicated brake rocker arms utilize springs to bias them against a cam, making them driveed by the cam. For example, in Chinese utility model patent CN201666172U, the rocker arm is biased against the brake cam by a spring mounted between a bracket and a pressure plate. This requires adding a special spring bracket to the engine, occupying significant space, making installation inconvenient, and costly. Since the rocker arm is constantly driven by the brake cam (moving during ignition and braking), it experiences useless movement during engine ignition, greatly increasing its usage frequency, wear, and impact. Furthermore, the spring must have a large preload to maintain constant contact between the engine brake rocker arm and the camshaft during camshaft rotation (preventing it from disengaging). Summary of the Invention:

[0005] The purpose of this embodiment is to provide a buffer mechanism for an engine brake rocker arm. This buffer mechanism for an engine brake rocker arm aims to solve the technical problems in the prior art, such as poor reliability of the locking mechanism of the engine brake rocker arm, the rocker arm requiring a spring with a large preload and a special bracket, large space occupation, inconvenient installation and high cost, as well as the rocker arm generating useless movement during engine ignition, increasing the frequency of use, wear and fuel consumption.

[0006] This embodiment discloses a buffer mechanism for an engine braking rocker arm. The rocker arm is rotatably mounted on the engine rocker arm shaft. The buffer mechanism applies a force between the rocker arm and the rocker arm shaft to increase the movement resistance of the rocker arm on the rocker arm shaft and keep the rocker arm in a non-collision position on the rocker arm shaft. In the non-collision position, one end of the rocker arm avoids the drive of the engine cam and the other end of the rocker arm avoids the action of the engine valve. The buffer mechanism includes an elastic body disposed between the rocker arm and the rocker arm shaft. The elastic body abuts against the rocker arm and the rocker arm shaft respectively. The elastic deformation of the elastic body applies a force between the rocker arm and the rocker arm shaft.

[0007] Optionally, the rocker arm has a receiving space, and the elastic body is disposed in the receiving space, with the elastic body abutting against the inner wall of the receiving space and the rocker arm shaft respectively.

[0008] Optionally, the receiving space is a receiving groove, the rocker arm includes a rocker arm shaft mounting hole for mounting the rocker arm shaft, the receiving groove is disposed in the rocker arm shaft mounting hole, and the elastic body abuts against the groove wall of the receiving groove and the rocker arm shaft respectively.

[0009] Optionally, the receiving groove is a circumferential groove extending circumferentially along the mounting hole of the rocker arm shaft, and the elastic body includes an arc-shaped spring, which is disposed on one side of the rocker arm shaft and placed within the circumferential groove. The arc-shaped spring includes a curved protrusion in the middle and two ends.

[0010] The curved protrusion and the two ends respectively abut against the groove wall of the circumferential groove and the rocker arm, or the curved protrusion and the two ends respectively abut against the rocker arm and the groove wall of the circumferential groove.

[0011] Optionally, the elastomer includes a leaf spring located in a slot on the rocker arm.

[0012] Optionally, the receiving groove is an annular groove extending circumferentially around the mounting hole of the rocker arm shaft, and the elastic body includes a C-type spring, which is arranged in a ring around the outside of the rocker arm shaft and placed in the annular groove. The C-type spring includes a curved protrusion in the middle and two ends.

[0013] The curved protrusion and the two ends respectively abut against the groove wall of the annular groove and the rocker arm, or the curved protrusion and the two ends respectively abut against the rocker arm and the groove wall of the annular groove.

[0014] Optionally, the C-type spring includes a leaf spring or a wire spring.

[0015] Optionally, the receiving space is a receiving hole, the rocker arm includes a rocker arm shaft mounting hole for mounting the rocker arm shaft, the receiving hole intersects with the rocker arm shaft mounting hole, the wall of the receiving hole and the wall of the rocker arm shaft mounting hole form a communicating connection, and the elastic body is disposed within the receiving hole.

[0016] A portion of the elastomer abuts against the wall of the receiving hole, and a portion of the elastomer abuts against the rocker arm through the connection port.

[0017] Optionally, the receiving hole is perpendicular to the rocker arm shaft mounting hole.

[0018] Optionally, the elastic body includes an open elastic pin, the opening of which faces either side of the rocker arm, the cylindrical surface of which abuts against the rocker arm shaft, and the force between the rocker arm and the rocker arm shaft causes the open elastic pin to deform circumferentially, and the opening becomes smaller.

[0019] Optionally, the elastomer includes a headed elastic pin, the headed elastic pin including an elastic pin body and an elastic pin head disposed at one end of the elastic pin body, the diameter of the elastic pin head being larger than the diameter of the elastic pin body, wherein the elastic pin head abuts against the wall of the receiving hole, and the elastic pin body abuts against the rocker arm shaft.

[0020] Optionally, the elastomer and the rocker arm may come into contact, and / or the elastomer and the rocker arm shaft may come into contact.

[0021] Compared with existing technologies, this embodiment offers positive and significant advantages. This embodiment positions the rocker arm in a position where it does not collide with either the brake cam or the engine valve, and is not driven by the brake cam. In the non-braking (ignition) state of the engine, the rocker arm does not move at all, reducing wear and fuel consumption, and enhancing reliability and durability. Furthermore, the rocker arm buffer mechanism of this embodiment does not occupy space (especially not increasing height) or add weight; it has a compact structure, is easy to install, has good reliability, and is low in cost. Attached image description:

[0022] Figure 1 This is a schematic diagram of the buffer mechanism of the engine brake rocker arm in Embodiment 1, wherein the engine is in a braking state (brake piston extended).

[0023] Figure 2 This is a schematic diagram of the buffer mechanism of the engine brake rocker arm in Embodiment 1, wherein the engine is in the ignition (brake piston retracted) state.

[0024] Figure 3 This is a schematic diagram of the elastomer in Example 1.

[0025] Figure 4 This is a schematic diagram of the buffer mechanism of the engine brake rocker arm in Embodiment 2, wherein the engine is in the ignition (brake piston retracted) state and the rocker arm is in position.

[0026] Figure 5 This is a schematic diagram of the engine brake rocker arm buffer mechanism in Example 3.

[0027] Figure 6 This is a schematic diagram of the engine brake rocker arm buffer mechanism in Example 4. Detailed implementation method:

[0028] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0029] It should be understood that the structures, proportions, sizes, etc., illustrated in the accompanying drawings of this specification are only used to complement the content disclosed in the specification for those skilled in the art to understand and read, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportional relationships, or adjustments to the size, without affecting the effects and purposes that the present invention can achieve, should still fall within the scope of the technical content disclosed in the present invention. Furthermore, the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., used in this specification to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing the embodiments of this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0030] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a replaceable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application based on the specific circumstances.

[0031] Example 1:

[0032] like Figure 1 and Figure 2 As shown, the engine brake rocker arm 210 (hereinafter referred to as rocker arm 210) is oscillatingly mounted on the rocker arm shaft 205 (the engine exhaust rocker arm can be mounted side-by-side with the engine brake rocker arm 210 on the same rocker arm shaft, but is not shown here). One end of the rocker arm 210 (here, the roller 235, or a pushrod mechanism) has an engine cam (brake cam 230), and the other end has an engine valve 301 (the valve stem of valve 301 has a valve stem cap 405, the valve bridge 400 presses on the valve stem cap 405, and the exhaust rocker arm acts on the center of the valve bridge 400 to drive the two exhaust valves). The engine braking mechanism 100 is installed inside the rocker arm 210 above the valve 301.

[0033] When engine braking is required, the engine braking control mechanism (not shown) activates the fuel supply, the braking mechanism 100 opens, the brake piston 160 extends downwards, and the rocker arm 210 is in the position shown. Figure 1 The connection positions are shown. Valve 301 is connected to the extended brake piston 160 via valve stem cap 405 (or directly via valve bridge 400); simultaneously, roller 235 is connected to the base circle 229 of brake cam 230. The movement of brake boss 231 (which may also have EGR or BGR bosses) on brake cam 230 is transmitted to engine valve 301 via rocker arm 210 and the extended brake piston 160 within the rocker arm, generating the valve movement required for engine braking. Of course, the engine ignition valve movement (including exhaust valve movement) generated by the conventional valve drive mechanism (not shown) is always present and does not interfere with the braking valve movement (the valve opening phases and heights for ignition and braking are different).

[0034] During normal ignition (non-engine braking) operation, the engine braking control mechanism (not shown) disconnects and discharges oil, the brake piston 160 retracts, and the rocker arm 210 tends to (automatically positioned by the cams 230 at both ends of the rocker arm 210 and the valve 301) as... Figure 2The two non-collision positions shown mean that one end of the rocker arm 210 has no interaction with the brake cam 230 (brake boss 231) and the other end has no interaction with the valve 301 (valve cap 405). In particular, a gap 212 is formed between the rocker arm 210 and the base circle 229 of the brake cam 230 (the gap 212 is set by the adjusting screw 105 and the locking nut 115, and its size is not less than the lift of the brake cam, that is, not less than the height of the brake boss 231). This makes the rocker arm 210 not driven by the cam 230, the movement of the cam 230 is lost, and no valve movement for engine braking is generated. Note that the valve movement for engine ignition (including exhaust valve movement) is generated by a conventional valve drive mechanism (not shown) and is not affected by the engine brake.

[0035] In practical applications, due to the bumps / vibrations generated by vehicle operation, the rocker arm 210 in the engine ignition state will not collide with either of the two positions on the rocker arm shaft 205. Figure 2 The rocker arm 210 may be disturbed, causing it to collide with the cam 230 and / or the valve 301. To eliminate this disturbance, the damping mechanism of the engine brake rocker arm in this embodiment is provided.

[0036] Reference Figures 1 to 3 The buffer mechanism 50 includes an elastic body 51 located between the rocker arm 210 and the rocker arm shaft 205. The elastic body 51 abuts against both the rocker arm 210 and the rocker arm shaft 205, allowing direct contact between them. The elastic deformation of the elastic body 51 applies a force between the rocker arm 210 and the rocker arm shaft 205, creating resistance to the movement of the rocker arm 210 on the rocker arm shaft 205, thus maintaining the rocker arm 210 in a "no-collision" position on the rocker arm shaft 205. Figure 2 In this way, one end of the rocker arm 210 avoids the drive of the cam 230 (clearance 212), and the other end of the rocker arm 210 avoids interaction with the engine valve 301. Once the rocker arm 210 is no longer driven by the cam 230, there will be no fly-off, and a complex, large, and expensive anti-fly-off mechanism is unnecessary. Abutment can be understood as a connection with a forceful action. Abutment can be a direct contact and forceful action between two parts (contact abutment), or a non-direct contact and forceful action, etc. Contact can be a fixed connection or a non-fixed connection. Specifically, the elastic body and the rocker arm make contact abutment, and / or the elastic body and the rocker arm shaft make contact abutment. For example, the elastic body contacts A, A contacts the rocker arm, and the elastic body and the rocker arm have non-contact abutment. For example, Figure 1 and Figure 2 In the middle, the elastomer and the rocker arm are in contact and abut each other.

[0037] In one embodiment of the present invention, the rocker arm 210 is provided with a receiving space, and an elastic body 51 is disposed in the receiving space. The elastic body 51 abuts against the inner wall of the receiving space and the rocker arm shaft 205 respectively.

[0038] In one embodiment of the present invention, the receiving space is a receiving groove, the rocker arm 210 includes a rocker arm shaft mounting hole 2051 for mounting the rocker arm shaft, the receiving groove is disposed within the rocker arm shaft mounting hole 2051, and the elastic body 51 abuts against the groove wall of the receiving groove and the rocker arm shaft 205 respectively. In one embodiment of the present invention, the elastic body 51 abuts against the rocker arm 210 and the rocker arm shaft 205 respectively.

[0039] In one embodiment of the present invention, the receiving groove is a circumferential groove 53 extending circumferentially along the rocker arm shaft mounting hole 2051. The elastic body includes an arc-shaped spring 51, which is disposed on one side of the rocker arm shaft 205 and placed within the circumferential groove 53. The arc-shaped spring 51 includes a curved protrusion 511 disposed in the middle and two ends 512, wherein the curved protrusion 511 and the two ends 512 respectively abut against the groove wall of the circumferential groove 53 and the rocker arm 210, or the curved protrusion 511 and the two ends 512 respectively abut against the rocker arm 210 and the groove wall of the circumferential groove 53. The curved protrusion 511 may abut against the bottom groove wall of the circumferential groove 53, and the two ends 512 may abut against the rocker arm 210. It should be noted that the ends 512 refer to the areas at both ends of the arc-shaped spring 51, and are not necessarily the outermost part, but may be at a certain distance from the outermost part.

[0040] In one embodiment of the present invention, the arc spring 51 can be a leaf spring ( Figure 3 ), located in the circumferential groove 53 on the rocker arm 210 ( Figure 1 and Figure 2 The width of the circumferential groove 53 is approximately greater than the width of the arc spring 51, and the length of the circumferential groove 53 is approximately greater than the length of the arc spring 51 after deformation. Note that the buffer mechanism 50 increases the motion (rotation) resistance of the rocker arm 210 on the rocker arm shaft 205, which increases frictional work (which is beneficial for increasing engine braking power), but does not increase engine fuel consumption, because no fuel is injected during engine braking, while the braking rocker arm 210 is stationary during engine ignition (no rotation means no frictional work).

[0041] Example 2:

[0042] Figure 4 This is a schematic diagram of the engine brake rocker arm buffer mechanism in Embodiment 2 in the engine ignition (brake piston retracted) state. This embodiment only describes the differences from Embodiment 1; the similarities will not be repeated.

[0043] The receiving groove is an annular groove 54 extending circumferentially around the rocker arm shaft mounting hole 2051. The annular groove 54 is a 360° annular groove. The elastic body includes a C-type spring 52, which is arranged in a ring around the outside of the rocker arm shaft 205 and placed in the annular groove 54. The C-type spring 52 includes a bent protrusion 521 in the middle and two ends 522. The bent protrusion 521 and the two ends 522 respectively abut against the groove wall of the annular groove 54 and the rocker arm 205, or the bent protrusion 521 and the two ends 522 respectively abut against the rocker arm 205 and the groove wall of the annular groove 54.

[0044] C-type spring 52 may include leaf springs and wire springs.

[0045] Example 3:

[0046] This embodiment only describes the differences from Embodiment 1; similarities will not be repeated. (Refer to...) Figure 5 In this embodiment, the accommodating space is an accommodating hole 74. The rocker arm 210 includes a rocker arm shaft mounting hole 2051 for mounting the rocker arm shaft. The accommodating hole 74 intersects with the rocker arm shaft mounting hole 2051. The hole wall of the accommodating hole 74 and the hole wall of the rocker arm shaft mounting hole 2051 form a communicating connection port 2052. An elastic body is disposed in the accommodating hole 74. A portion of the elastic body abuts against the hole wall of the accommodating hole 2051, and a portion of the elastic body abuts against the rocker arm 210 through the connection port 202.

[0047] In one embodiment of the present invention, the receiving hole 74 is perpendicular to the rocker arm shaft mounting hole 2051.

[0048] In one embodiment of the present invention, the elastic body includes an open elastic pin 72, which includes an opening and a cylindrical surface. The opening is provided between the cylindrical surfaces. The opening of the open elastic pin 72 faces either side of the rocker arm 210. The cylindrical surface of the open elastic pin abuts against the rocker arm shaft. The force between the rocker arm and the rocker arm shaft causes the open elastic pin to undergo circumferential deformation, and the opening becomes smaller.

[0049] It should be noted that the planes on both sides of the rocker arm 210 are approximately perpendicular to the axial direction of the rocker arm shaft mounting hole 2051.

[0050] Example 4:

[0051] Figure 6The engine braking rocker arm buffer mechanism of Embodiment 4 is described in this embodiment only, focusing on the differences from Embodiments 1 and 3; similarities are not repeated. The buffer mechanism 80 includes a headed elastic pin 82, which includes an elastic pin body 85 and an elastic pin head 81 disposed at one end of the elastic pin body 85. The diameter of the elastic pin head 81 is larger than the diameter of the elastic pin body 85. The elastic pin head 81 abuts against the wall of the receiving hole 84, and the elastic pin body 85 abuts against the rocker arm shaft.

[0052] The headed elastic pin 82 is located within the receiving hole 84 on the rocker arm 210. The diameter of the receiving hole 84 is the same as the diameter of the elastic pin head 81 of the headed elastic pin 82. The receiving hole 84 is perpendicular to the rocker arm shaft 205, which can be understood as the receiving hole 84 being perpendicular to the rocker arm shaft mounting hole 2051. Note that after the rocker arm 210 is mounted on the rocker arm shaft 205, the headed elastic pin 82 undergoes elastic (bending) deformation, thereby generating a force between the rocker arm 210 and the rocker arm shaft 205.

[0053] The examples above are illustrative of this embodiment and not intended to limit it. In fact, those skilled in the art can readily modify and vary this embodiment within its scope and principles. For example, a certain function described or illustrated in one specific mechanism can be used in another specific mechanism, resulting in a new mechanism. The rocker arm in the embodiment can be other types of rocker arms besides an engine braking rocker arm, such as an EGR rocker arm or a rocker arm for engine variable valve actuation. Furthermore, the engine braking mechanism within the rocker arm can be of different types, and besides braking mechanisms, it can also be other mechanisms such as EGR. Also, the position and installation method of the buffer mechanism can be different. In addition, the form and installation of the elastomer can also be different. Therefore, this embodiment will include the above modifications and variations, provided they fall within the scope of the appended claims or equivalent claims.

Claims

1. A buffer mechanism for an engine brake rocker arm, characterized in that: The rocker arm is rotatably mounted on the rocker arm shaft of the engine. The buffer mechanism applies a force between the rocker arm and the rocker arm shaft to increase the movement resistance of the rocker arm on the rocker arm shaft and keep the rocker arm in a non-collision position on the rocker arm shaft. In the non-collision position, one end of the rocker arm avoids the drive of the engine cam and the other end of the rocker arm avoids the action of the engine valve. The buffer mechanism includes an elastic body disposed between the rocker arm and the rocker arm shaft. The elastic body abuts against the rocker arm and the rocker arm shaft respectively. The elastic deformation of the elastic body applies a force between the rocker arm and the rocker arm shaft.

2. The buffer mechanism of the engine brake rocker arm as described in claim 1, characterized in that: The rocker arm has a receiving space, and the elastic body is disposed in the receiving space. The elastic body abuts against the inner wall of the receiving space and the rocker arm shaft respectively.

3. The buffer mechanism of the engine brake rocker arm as described in claim 2, characterized in that: The accommodating space is an accommodating groove, the rocker arm includes a rocker arm shaft mounting hole for mounting the rocker arm shaft, the accommodating groove is disposed in the rocker arm shaft mounting hole, and the elastic body abuts against the groove wall of the accommodating groove and the rocker arm shaft respectively.

4. The buffer mechanism of the engine brake rocker arm as described in claim 3, characterized in that: The receiving groove is a circumferential groove extending circumferentially along the mounting hole of the rocker arm shaft. The elastic body includes an arc-shaped spring, which is disposed on one side of the rocker arm shaft and placed within the circumferential groove. The arc-shaped spring includes a curved protrusion in the middle and two ends. The curved protrusion abuts against the wall of the circumferential groove and the two ends abut against the rocker arm, or the curved protrusion abuts against the rocker arm and the two ends abut against the wall of the circumferential groove. Optionally, the elastomer includes a leaf spring located in a slot on the rocker arm.

5. The buffer mechanism of the engine brake rocker arm as described in claim 3, characterized in that: The receiving groove is an annular groove extending circumferentially around the mounting hole of the rocker arm shaft. The elastic body includes a C-type spring, which is arranged in a ring around the outside of the rocker arm shaft and placed within the annular groove. The C-type spring includes a curved protrusion in the middle and two ends. The curved protrusion abuts against the wall of the annular groove and the two ends abut against the rocker arm, or the curved protrusion abuts against the rocker arm and the two ends abut against the wall of the annular groove. Optionally, the C-type spring includes a leaf spring or a wire spring.

6. The buffer mechanism of the engine brake rocker arm as described in claim 2, characterized in that: The receiving space is a receiving hole, the rocker arm includes a rocker arm shaft mounting hole for mounting the rocker arm shaft, the receiving hole intersects with the rocker arm shaft mounting hole, the hole wall of the receiving hole and the hole wall of the rocker arm shaft mounting hole form a communicating connection, the elastic body is disposed in the receiving hole, wherein a portion of the elastic body abuts against the hole wall of the receiving hole, and a portion of the elastic body abuts against the rocker arm through the connection.

7. The buffer mechanism of the engine brake rocker arm as described in claim 6, characterized in that: The receiving hole is perpendicular to the rocker arm shaft mounting hole.

8. The buffer mechanism of the engine brake rocker arm as described in claim 6, characterized in that: The elastic body includes an open elastic pin, the opening of which faces either side of the rocker arm. The cylindrical surface of the open elastic pin abuts against the rocker arm shaft. The force between the rocker arm and the rocker arm shaft causes the open elastic pin to deform circumferentially, and the opening becomes smaller.

9. The buffer mechanism of the engine brake rocker arm as described in claim 6, characterized in that: The elastic body includes a headed elastic pin, which includes an elastic pin body and an elastic pin head disposed at one end of the elastic pin body. The diameter of the elastic pin head is larger than the diameter of the elastic pin body. The elastic pin head abuts against the wall of the receiving hole, and the elastic pin body abuts against the rocker arm shaft.

10. The buffer mechanism of the engine brake rocker arm as described in claim 6, characterized in that: The elastomer and the rocker arm are in contact, and / or the elastomer and the rocker arm shaft are in contact.

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