Construction machine

Abstract

The work device (8) is provided with: a lower boom (9) and an upper boom (10) rotatably installed on the upper rotating body (3); an intermediate arm (11) and an arm (12) rotatably installed on the front end of the upper boom (10); a work tool (13) installed on the front end of the arm (12); a work tool cylinder (22) installed on the arm (12) to rotate the work tool (13); and a connecting rod (16) rotatably installed on the front end side of the arm (12) and connecting the work tool cylinder (22) and the work tool (13). The work tool cylinder (22) is arranged on the lower surface (12B) side of the arm (12), and a cylinder guard (23) is fixed to the first connecting rod (17) of the connecting rod (16). The cylinder guard (23) is synchronously displaced with the extension and retraction action of the work tool cylinder (22) and is interposed between the work tool (13) and the work tool cylinder (22), thereby protecting the work tool cylinder (22).

Description

Technical Field

[0001] This disclosure relates to an engineering machine equipped with a working device operated by a hydraulic cylinder. Background Technology

[0002] A hydraulic excavator, a type of construction machinery, consists of a self-propelled lower traveling body and a rotating upper body mounted on the lower traveling body. A working device is installed on the front side of the upper rotating body. Furthermore, when demolishing structures with significant ground height, such as high-rise buildings, a demolition working device is installed on the front side of the upper rotating body for demolition operations.

[0003] Demolition equipment typically comprises: a boom rotatably connected at its base to a rotating frame on an upper rotating body; a stick rotatably connected to the front end of the boom; and a crusher or other auxiliary tool rotatably connected to the front end of the stick. A boom cylinder is installed between the rotating frame and the boom to raise and lower the boom, and a stick cylinder is installed between the boom and the stick to rotate the stick at the front end of the boom. An auxiliary tool cylinder (accessory cylinder) is installed between the stick and the auxiliary tool to rotate the auxiliary tool at the front end of the stick; this auxiliary tool cylinder is typically located on the upper surface of the stick.

[0004] In demolition sites of high-rise buildings or covered areas, the working tools have a narrower range of motion compared to the boom, and they mostly operate below the upper surface of the boom. Therefore, the working tool cylinder, located on the upper surface of the boom, is usually the part with the greatest ground height, posing a higher risk of contact with the ceiling, reinforcing steel, or other structural elements of the building to be demolished.

[0005] Therefore, in the prior art, a cylinder guard has been proposed, comprising a tube-side guard with one end mounted on the tube side of the tool cylinder and a rod-side guard with one end mounted on the rod side, wherein the other end of the tube-side guard and the other end of the rod-side guard are movably connected. The cylinder guard has a guide on the other end of the tube-side guard, and the other end of the rod-side guard is supported by the guide to slide. Thus, the tool cylinder can be covered from above by the tube-side guard and the rod-side guard throughout its entire stroke (Patent Document 1).

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2014-15780 Summary of the Invention

[0009] However, in the cylinder guard of Patent Document 1, the rod-side guard slides relative to the guide of the pipe-side guard through the extension and retraction of the working tool cylinder. This results in the problem that debris such as steel bars and concrete from demolition work can be carried into the sliding part between the rod-side and pipe-side guards, hindering the smooth sliding of the rod-side guard. Furthermore, in addition to the pipe-side and rod-side guards, bolts, pins, and other mounting components are also required to install them onto the pipe and rod. Therefore, the cylinder guard of Patent Document 1 suffers from increased component quantity, increased installation time, and increased manufacturing cost.

[0010] The purpose of this invention is to provide an engineering machine that can protect the cylinder of the working tool.

[0011] The engineering machinery of the present invention comprises a self-propelled vehicle body and a working device mounted on the vehicle body. The working device includes: a boom rotatably mounted on the vehicle body; a stick rotatably mounted on the front end of the boom; a working tool rotatably mounted on the front end of the stick; a working tool cylinder, one end of which is mounted on the stick to rotate the working tool; and a connecting rod rotatably mounted on the front end of the stick and connecting the other end of the working tool cylinder to the working tool. The working tool cylinder is disposed on the lower surface of the stick opposite to the boom when the stick is folded to the boom side. A cylinder guard is provided on the connecting rod, which rotates synchronously with the extension and retraction of the working tool cylinder and is located between the working tool and the working tool cylinder.

[0012] According to the present invention, the cylinder guard rotates synchronously with the extension and retraction of the tool cylinder, moving integrally with the connecting rod while positioned between the tool and the tool cylinder. As a result, for example, when using the tool for demolition work, the cylinder guard can prevent debris flying from the building from colliding with the tool cylinder, thereby protecting the tool cylinder. Attached Figure Description

[0013] Figure 1 This is a left-side view of a hydraulic excavator used for demolition operations, according to an embodiment of the present invention.

[0014] Figure 2 This is a left-side view showing the boom, connecting rod, and cylinder guard when the tool cylinder is in the retracted state.

[0015] Figure 3 This is a left-side view of the boom, connecting rod, and cylinder guard when the working tool cylinder is in the retracted or extended state.

[0016] Figure 4 This is a left-side view showing the boom, connecting rod, and cylinder guard when the tool cylinder is in the extended state.

[0017] Figure 5 From Figure 2 Observe the main view of the boom, connecting rod, tool cylinder, and cylinder guard in the direction of arrow VV.

[0018] Figure 6 This is a three-dimensional diagram representing a single cylinder protective component.

[0019] Figure 7 This is a left-side view showing a hydraulic excavator performing demolition work on a building.

[0020] Figure 8 This is a left-side view of a work device used for demolition work when the work tool cylinder is in the retracted state.

[0021] Figure 9 This is a left-side view of a work device that performs demolition work while the work tool cylinder is in a state between retracted and extended.

[0022] Figure 10 This is a left-side view of a work device used for demolition work when the work tool cylinder is in the extended position. Detailed Implementation

[0023] The following description will take the application of the engineering machinery embodiment of the present invention to a hydraulic excavator for demolition operations as an example, and will be explained in detail with reference to the accompanying drawings. Furthermore, in this embodiment, the travel direction of the hydraulic excavator is defined as the forward-backward direction, and the direction orthogonal to the travel direction is defined as the left-right direction.

[0024] The hydraulic excavator 1 for demolition operations comprises: a self-propelled tracked lower traveling body 2; an upper rotating body 3 rotatably mounted on the lower traveling body 2; and a working device 8 disposed at the front of the upper rotating body 3. The lower traveling body 2 and the upper rotating body 3 constitute the body of the hydraulic excavator 1. The hydraulic excavator 1 is suitable for demolition operations of structures with large ground height, such as high-rise buildings.

[0025] The upper rotating body 3 comprises: a rotating frame 4 serving as a base; a counterweight 5 disposed at the rear end of the rotating frame 4; a compartment 6 disposed on the front left side of the rotating frame 4; and an equipment housing 7 disposed on the front side of the counterweight 5. The compartment 6 is divided into a cab for the operator to operate the hydraulic excavator 1. Inside the compartment 6 are a travel lever / pedal device for controlling the movement of the lower traveling body 2, and an operating lever device for controlling the rotation of the upper rotating body 3 and the operation of the working device 8 (all not shown). The equipment housing 7 houses mounted equipment such as the engine, hydraulic pump, and heat exchanger (not shown).

[0026] A support bracket (not shown) is integrally provided on the front end side of the rotating frame 4, which rises from the base plate in a mountain shape. This support bracket supports the base end side of the lower boom 9 (described later) so that it can rotate, and also supports the base end side of the boom cylinder 19 so that it can rotate.

[0027] The multi-boom type working device 8 is installed at the front end of the rotating frame 4 that constitutes the upper rotating body 3. The working device 8 is configured to include: a lower boom 9 and an upper boom 10 that constitute the boom, an intermediate stick 11 and a stick 12 that constitute the stick, a working tool 13, and a connecting rod 16.

[0028] The base end of the lower boom 9 is rotatably mounted to the front end of the rotating frame 4 (the support bracket). The base end of the upper boom 10 is fixed to the front end of the lower boom 9 using fasteners such as bolts. The base end of the intermediate stick 11 is rotatably connected to the front end of the upper boom 10 using pins 11A. A first bracket 11B and a second bracket 11C are arranged adjacent to each other on the intermediate stick 11. The base end of the stick 12 is rotatably connected to the front end of the intermediate stick 11 using pins 11D.

[0029] The boom 12 is formed as a rectangular cylindrical body with a quadrilateral cross-section, surrounded by an upper surface 12A, a lower surface 12B, and left and right side surfaces 12C. For example... Figure 10 As shown, when the stick 12 is folded towards the upper boom 10, the lower surface 12B of the stick 12 is opposite to the upper boom 10. A first bracket 12D and a second bracket 12E are arranged adjacent to each other on the lower surface 12B of the stick 12. At the front end of the stick 12, a joint device 14 for the working tool 13 is rotatably connected using a pin 12F.

[0030] The working tool 13 is rotatably mounted on the front end of the boom 12. In this embodiment, the working tool 13 is composed of the joint device 14 and the crusher 15.

[0031] The coupling device 14 is used to replace various auxiliary devices such as buckets, grab buckets, and crushers 15, which are mounted on the front end of the boom 12 according to the work requirements of the hydraulic excavator 1. In this embodiment, the crusher 15 for dismantling operations is mounted on the coupling device 14, and the coupling device 14 and the crusher 15 together constitute the working tool 13. Figure 2 As shown, the connector device 14 has a base component 14A, a fixed hook 14B fixed to the base component 14A, and a movable hook 14C. The movable hook 14C is movably disposed on the base component 14A and can move in a direction relative to the fixed hook 14B, either closer to or further away from it.

[0032] The crusher 15 used for demolition operations is rotatably mounted to the front end of the boom 12 via a coupling device 14. Two pins 15A are provided on the base end side of the crusher 15, which engage with the fixed hook 14B and movable hook 14C of the coupling device 14, thereby fixing the crusher 15 to the coupling device 14. The crusher 15 has left and right claw components 15B that are opened and closed by hydraulic cylinders. The left and right claw components 15B crush buildings and the like, and to prevent the debris from falling, the debris is placed in a stable location nearby.

[0033] Connecting rod 16 is located at the front end of boom 12, connecting the working tool cylinder 22 (described later) and the working tool 13. For example... Figures 2 to 5 As shown, the connecting rod 16 is composed of a first connecting rod 17 and a second connecting rod 18. By rotating synchronously with the extension and retraction of the working tool cylinder 22, the working tool 13 rotates relative to the boom 12.

[0034] The first connecting rod 17 consists of a pair of connecting rod plates extending in a straight line, facing each other in the left-right direction across the boom 12. The middle portion of the first connecting rod 17 is rotatably connected via pin 17A to a position adjacent to the connecting portion (pin 12F) of the joint device 14 on the front end side of the boom 12. One end 17B of the first connecting rod 17 is located on the lower surface 12B side of the boom 12 and is connected to the rod 22B of the working tool cylinder 22. The other end 17C of the first connecting rod 17 is located on the upper surface 12A side of the boom 12 and is connected to the second connecting rod 18. Two seat screws (not shown) are respectively provided on the left and right ends 17B sides of the first connecting rod 17.

[0035] The second link 18 is disposed between the other end 17C of the first link 17 and the connector device 14, connecting the two. One end of the second link 18 in the longitudinal direction is rotatably connected to the other end 17C of the first link 17 via pin 18A. The other end of the second link 18 in the longitudinal direction is rotatably connected to a position in the base component 14A of the connector device 14 away from pin 12F by pin 18B.

[0036] A pair of boom cylinders 19 (two cylinders) are provided between the rotating frame 4 and the lower boom 9 (left side only shown in the figure). The bottom side of the boom cylinder 19 is rotatably mounted to the support bracket of the rotating frame 4. The rod side of the boom cylinder 19 is rotatably connected to the front end of the lower boom 9 using pins 19A. A pair of intermediate stick cylinders 20 (two cylinders) are provided between the upper boom 10 and the intermediate stick 11 (left side only shown in the figure). The bottom side of the intermediate stick cylinder 20 is rotatably connected to the upper boom 10 using pins 20A, and the rod side of the intermediate stick cylinder 20 is rotatably connected to the first bracket 11B of the intermediate stick 11 using pins 20B. A stick cylinder 21 is provided between the intermediate stick 11 and the stick 12. The bottom side of the boom cylinder 21 is rotatably connected to the second bracket 11C of the intermediate boom 11 using a pin 21A, and the boom side of the boom cylinder 21 is rotatably connected to the first bracket 12D of the boom 12 using a pin 21B.

[0037] The working tool cylinder 22 is disposed on the lower surface 12B side of the boom 12, between the boom 12 and the connecting rod 16. The working tool cylinder 22 includes: a tube 22A; a piston (not shown) slidably disposed within the tube 22A; and a rod 22B, the base end of which is mounted to the piston, and the front end protruding from the tube 22A. One end of the working tool cylinder 22 (tube 22A) along its length is rotatably connected to the second bracket 12E of the boom 12 using a pin 22C. The other end of the working tool cylinder 22 (rod 22B) along its length is rotatably connected to one end 17B of the first connecting rod 17 using a pin 22D.

[0038] Therefore, by extending and retracting the working tool cylinder 22, the first connecting rod 17 rotates around the connection point (pin 17A) with the boom 12, and the movement of the first connecting rod 17 is transmitted to the joint device 14 via the second connecting rod 18. Thus, the working tool 13, composed of the joint device 14 and the crusher 15, rotates around the connection point (pin 12F) with the boom 12. In this embodiment, by extending and retracting the working tool cylinder 22 between the retracted and extended states, the crusher 15 rotates while... Figures 8 to 10 The building is being demolished while the structure is being rotated within the indicated range.

[0039] In this configuration, the tool cylinder 22 is positioned on the lower surface 12B side of the boom 12. Therefore, when the tool 13 is rotated upwards around the pin 12F, the tool cylinder 22 extends. Conversely, when the tool 13 is rotated downwards, the tool cylinder 22 retracts. Thus, compared to the case where the tool cylinder 22 is positioned on the upper surface 12A side of the boom 12, when using the tool 13 to lift waste materials such as steel bars and concrete generated during demolition work, the extension action performed by the tool cylinder 22 generates greater force.

[0040] Next, refer to Figures 2 to 6 The cylinder guard 23 used in this embodiment will be described. The cylinder guard 23 is fixed to a pair of first connecting rods 17 constituting the connecting rod 16. The cylinder guard 23 is used when the working tool cylinder 22 is in the retracted state ( Figure 2 The state shown) and the elongated state ( Figure 4 When extending or retracting between the states shown, it is positioned between the working tool 13 and the working tool cylinder 22, protecting the working tool cylinder 22.

[0041] like Figure 6 As shown, the cylinder guard 23 is formed into a rectangular plate using steel plate or similar material, and is configured to include a mounting plate portion 23A mounted on a pair of first connecting rods 17 and a guard plate portion 23B integrally disposed in a state inclined relative to the mounting plate portion 23A. The guard plate portion 23B is integrated into the working tool cylinder 22. Figure 2 The tilt angle relative to the mounting plate 23A is set in the manner that it is closest to the working tool cylinder 22 in the retracted state, as shown. Figure 2 and Figure 5 As shown, the cylinder guard 23 has a length dimension that covers the entire length of the working tool cylinder 22 in its retracted state. Furthermore, the width dimension of the cylinder guard 23 is set to be slightly larger than the interval between the pair of first connecting rods 17, and curved portions 23C are provided at both ends of the cylinder guard 23 in the width direction. These curved portions 23C are bent at right angles relative to the mounting plate portion 23A and the guard plate portion 23B, improving the overall strength of the cylinder guard 23.

[0042] The mounting plate portion 23A of the cylinder guard 23 has multiple (e.g., four) bolt insertion holes 23D. These bolt insertion holes 23D correspond to two seat screws (not shown) on each of the pair of first connecting rods 17 constituting the connecting rod 16. Therefore, by screwing the bolts 24 inserted into the bolt insertion holes 23D onto the seat screws of the pair of first connecting rods 17, the cylinder guard 23 is fixed to the first connecting rod 17. Thus, one end 23E of the cylinder guard 23 in the longitudinal direction is fixed to the first connecting rod 17, while the other end 23F in the longitudinal direction becomes a free end. The angle θ formed between the guard plate portion 23B of the cylinder guard 23 and the first connecting rod 17 remains constant regardless of the extension and retraction of the tool cylinder 22.

[0043] Furthermore, semi-circular cutouts 23G are formed in the curved portions 23C located at both ends of the mounting plate portion 23A in the width direction, at positions overlapping with the axis of the pin 22D connecting the working tool cylinder 22 and the first connecting rod 17. When the cylinder guard 23 is installed on the first connecting rod 17, these cutouts 23G prevent the two ends of the pin 22D from interfering with the curved portions 23C.

[0044] The hydraulic excavator 1 of this embodiment has the structure described above, for example, as follows: Figure 7 As shown, the hydraulic excavator 1 approaches the building 100 to be demolished via its lower traveling body 2. Then, the boom cylinder 19, intermediate stick cylinder 20, and stick cylinder 21 of the working device 8 are extended, causing the lower boom 9, upper boom 10, intermediate stick 11, and stick 12 to stand upright in a straight line. With the working tool 13 positioned at a high point, the hydraulic excavator 1 demolishes the building 100 using the crusher 15, disposing of waste materials such as steel bars and concrete onto the loading dock of a transport vehicle (not shown).

[0045] Here, when performing the demolition work with the working device 8 upright in a straight line, such as Figure 8 As shown, by retracting the tool cylinder 22, the tool 13 rotates downwards around pin 12F, and the crusher 15 is used to demolish the building 100. Thus, with the working device 8 upright in a straight line, the tool 13 (crusher 15) typically performs demolition work in a downward-rotating posture around pin 12F. Demolition work is not typically performed with the tool 13 rotating upwards around pin 12F. In this state, the tool cylinder 22 is close to the building 100. However, by retracting the tool cylinder 22, the cylinder guard 23 can cover the entire tool cylinder 22. As a result, when demolishing the building 100 using the crusher 15, even if debris such as steel bars and concrete scatters around the crusher 15, the cylinder guard 23 can prevent these debris from colliding with the tool cylinder 22, thereby protecting the tool cylinder 22.

[0046] And, as Figure 9As shown, during demolition work with the boom 12 extending horizontally from the front end of the intermediate boom 11, the tool cylinder 22 is positioned between a retracted and an extended state. Then, with the tool 13 facing the building 100, the building 100 is demolished using the crusher 15. Thus, with the boom 12 extended horizontally, demolition work is generally not performed with the tool 13 rotating upwards around pin 12F. In this state, the cylinder guard 23, by facing the building 100, protects the tool cylinder 22 from damage caused by flying debris such as steel bars and concrete from the building 100.

[0047] And, as Figure 10 As shown, during demolition work with the boom 12 extending downwards from the front end of the intermediate boom 11, the tool cylinder 22 moves away from the building 100, and the boom 12 is positioned between the building 100 and the tool cylinder 22. Furthermore, the front end of the rod 22B of the tool cylinder 22, which protrudes from the front end of the boom 12, is covered by the cylinder guard 23. In this state, the boom 12 can protect most of the tube 22A and rod 22B of the tool cylinder 22 from debris such as steel bars and concrete flying from the building 100. On the other hand, the front end of the rod 22B of the tool cylinder 22 is protected by the cylinder guard 23.

[0048] Thus, in this embodiment, the cylinder guard 23 remains positioned between the tool 13 and the tool cylinder 22 when the tool cylinder 22 extends and retracts between its retracted and extended states, thereby protecting the tool cylinder 22. In this case, one end 23E of the cylinder guard 23 is fixed to the first connecting rod 17 of the connecting rod 16 using bolts 24, and rotates integrally with the first connecting rod 17 to protect the tool cylinder 22. Therefore, compared to cylinder guards that, for example, assemble the rod-side guard and the tube-side guard in a sliding manner as in the prior art, the cylinder guard 23 does not suffer from malfunctions due to debris being carried into the sliding part. Therefore, the cylinder guard 23 can reliably protect the tool cylinder 22 for a long period of time.

[0049] Furthermore, the cylinder guard 23 is a single component and can be easily installed on the first connecting rod 17 using bolts 24. Therefore, compared to cylinder guards consisting of two components, such as rod-side guards and tube-side guards, as in the prior art, the number of components and installation time can be reduced. Consequently, the cylinder guard 23 also contributes to reducing manufacturing costs.

[0050] Thus, in the hydraulic excavator 1 of this embodiment, the working device 8 includes: a lower boom 9 and an upper boom 10, which are rotatably mounted on the upper rotating body 3; an intermediate stick 11 and a stick 12, which are rotatably mounted on the front end of the upper boom 10; a working tool 13, which is rotatably mounted on the front end of the stick 12; a working tool cylinder 22, one end of which is mounted on the stick 12 to rotate the working tool 13; and a connecting rod 16, which is rotatably mounted on the front end side of the stick 12 and connects the other end of the working tool cylinder 22 to the working tool 13. The working tool cylinder 22 is disposed on the lower surface 12B side of the stick 12 opposite to the upper boom 10 when the stick 12 is folded to the upper boom 10. A cylinder guard 23 is provided on the connecting rod 16. The cylinder guard 23 rotates synchronously with the extension and retraction of the working tool cylinder 22 and is located between the working tool 13 and the working tool cylinder 22.

[0051] According to this structure, the cylinder guard 23 rotates synchronously with the extension and retraction of the tool cylinder 22, thereby moving integrally with the connecting rod 16 while positioned between the tool 13 and the tool cylinder 22. As a result, for example, when using the tool 13 for demolition work, the cylinder guard 23 can prevent debris flying from the building from colliding with the tool cylinder 22, thus protecting the tool cylinder 22.

[0052] In this embodiment, the cylinder guard 23 has a length dimension that covers the entire length of the working tool cylinder 22 in its retracted state. It is formed of a plate with curved portions 23C at both ends in the width direction and is fixed relative to the first connecting rod 17 at a constant angle. With this structure, it is unnecessary to provide a sliding portion between the cylinder guard 23 and the first connecting rod 17. Therefore, debris generated during demolition operations will not be carried into this sliding portion, preventing malfunction of the cylinder guard 23. Furthermore, the curved portions 23C improve the overall strength of the cylinder guard 23.

[0053] In this embodiment, one end 23E of the cylinder guard 23 along its length is fixed to the first connecting rod 17, while the other end 23F along its length becomes a free end. According to this structure, the cylinder guard 23 can rotate and displace together with the first connecting rod 17 according to the extension and retraction of the tool cylinder 22, thus protecting the tool cylinder 22.

[0054] In another embodiment, a crusher 15 is shown mounted on the front end of the boom 12 via a connector 14. However, the present invention is not limited to this, and a structure in which the crusher 15 is directly mounted on the front end of the boom 12 may also be adopted.

[0055] In another embodiment, an example is shown where a stick 12 is mounted on the front end of the upper boom 10 via an intermediate stick 11. However, the present invention is not limited to this, and the stick 12 can also be mounted directly on the front end of the upper boom 10.

[0056] Furthermore, in one embodiment, a crusher 15 for demolition work is shown mounted on the front end of the boom 12 via a joint device 14. However, the present invention is not limited to this and can also be widely applied to hydraulic excavators equipped with other working tools such as buckets, grabs, and lifting magnets.

[0057] Symbol Explanation

[0058] 1—Hydraulic excavator; 2—Lower traveling body (body); 3—Upper rotating body (body); 8—Working device; 9—Lower boom (boom); 10—Upper boom (boom); 11—Intermediate stick (stick); 12—Stick; 12B—Lower surface; 13—Working tool; 16—Connecting rod; 17—First connecting rod; 18—Second connecting rod; 22—Working tool cylinder; 23—Cylinder guard; 23C—Bend; 23E—One end; 23F—The other end.

Claims

1. An engineering machine comprising a self-propelled vehicle body and a working device disposed on said vehicle body, The working device includes: A boom, which is rotatably mounted to the vehicle body; The stick is rotatably mounted on the front end of the boom; The working tool is rotatably mounted on the front end of the boom; A tool cylinder, one end of which is mounted to the boom for rotating the tool; and A connecting rod, rotatably mounted on the front end of the boom, connects the other end of the working tool cylinder to the working tool. The engineering machinery is characterized by the following features: The working tool cylinder is positioned on the lower surface of the stick, opposite the boom, when the stick is folded to the boom side. A cylinder guard is provided on the connecting rod. This cylinder guard rotates synchronously with the extension and retraction of the working tool cylinder and is positioned between the working tool and the working tool cylinder. The cylinder guard has a length dimension that covers the entire length of the working tool cylinder in its retracted state, is formed by a plate with curved portions at both ends in the width direction, and is fixed to the connecting rod at a constant angle.

2. The engineering machinery according to claim 1, characterized in that, One end of the cylinder guard is fixed to the connecting rod along its length, while the other end of the cylinder guard is a free end.

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