Lightweight shock absorber

Abstract

The utility model relates to the technical field of automobile shock absorbers, in particular to a light shock absorber which comprises a shock absorber assembly, a double-layer upper support, a vibration isolation inner core, a compression buffer block, an outer sleeve dustproof cylinder and an inner sleeve dustproof cylinder. By combining the strength advantage of a stamping process and the cost benefit of steel, compared with aluminum alloy, the weight is reduced by 15%, meanwhile, the compressive strength is improved by 30%, the use of a complex reinforcing rib structure is avoided, the material cost, the development difficulty of the shock absorber and the mold opening difficulty of parts are reduced, and meanwhile the overall performance and reliability of the shock absorber are improved; by means of the double dustproof covers with the inner layer and the outer layer, the sediment invasion amount is reduced to be below 20% of that of a traditional structure, the service life of the buffer block and the oil seal is remarkably prolonged, and the durability and the dustproof performance of the shock absorber are improved; the utility model has the characteristics of easy maintenance, disassembly and assembly, and high adaptability.

Description

Technical Field

[0001] This utility model relates to the field of automotive shock absorber technology, specifically a lightweight shock absorber. Background Technology

[0002] Traditional shock absorber upper supports mostly use independent aluminum alloy structures, which can achieve weight reduction, but have the following drawbacks:

[0003] Insufficient material strength: Under long-term alternating loads, the aluminum alloy frame is prone to stress concentration at the annular groove, leading to fracture and affecting the safety of the entire vehicle;

[0004] Weak dustproof performance: The single-layer dust cover design is difficult to completely prevent the intrusion of mud and sand, which accelerates the wear of the buffer block and oil seal;

[0005] Cost versus weight conflict: Existing lightweight solutions require complex reinforcing rib structures to compensate for rigidity, leading to increased material costs.

[0006] Currently, the main improvement solutions for vibration dampers are to enhance their adaptive performance by optimizing the valve body structure, but these solutions do not address the inherent defects of the upper support structure. There are also technical solutions that use a double-layer skeleton embedded bearing design to reduce weight, but these still rely on aluminum alloy materials.

[0007] Therefore, it is necessary to design a lightweight vibration damper that can reduce weight while improving compressive strength and dustproof performance, and achieve lightweighting and improved durability of the vibration damper in a low-cost manner. Utility Model Content

[0008] The purpose of this invention is to overcome the shortcomings of the prior art and provide a lightweight vibration damper that reduces weight while improving compressive strength and dustproof performance. It achieves lightweighting and improved durability of the vibration damper in a low-cost manner.

[0009] To achieve the above objectives, this utility model discloses a lightweight vibration damper, comprising a vibration damper assembly, a double-layer upper support, a vibration isolation core, a compression buffer block, an outer dustproof sleeve, and an inner dustproof sleeve. The vibration damper assembly is a double-cylinder hydraulic vibration damper structure, including a piston rod, a dust cover, an outer cylinder, an inner cylinder, an oil seal, a guide, a recovery buffer block, a recovery buffer block seat, a piston valve system, a bottom valve system, and a bottom cover. The outer cylinder is a tubular structure that is thinner at the top and thicker at the bottom. A bottom cover is welded to the bottom of the outer cylinder, and the top of the outer cylinder has a rolled edge structure that abuts against the end face of the oil seal. The dust cover is interference-fitted onto the top of the outer cylinder. The inner cylinder is located inside the outer cylinder. A bottom valve system is installed between one end of the inner cylinder and the bottom cover, and a guide is installed between the other end of the inner cylinder and the oil seal. One end of the piston rod is located inside the inner cylinder. The recovery buffer block seat is fitted and riveted to the outside of one end of the piston rod. The recovery buffer block is installed on the recovery buffer block seat. A piston valve system is installed at one end of the piston rod. The other end of the piston rod passes through the guide, oil seal, and dust cover and is connected to the double-layer upper support. The vibration isolation inner core and the compression buffer block are respectively fitted outside the piston rod. The vibration isolation inner core is installed inside the double-layer upper support. The upper end of the compression buffer block is embedded in the lower end of the double-layer upper support. The upper end of the outer dust cover is connected to the double-layer upper support. The lower end of the outer dust cover extends to the outside of the compression buffer block. The upper end of the inner dust cover is connected to the compression buffer block. The lower end of the inner dust cover extends to the outside of the compression damper assembly. The side of the dust cover facing the compression buffer block has a rough structure.

[0010] The double-layer upper support includes a first shell, a second shell, a top plate, and a locking cover plate. The top plate is installed on the upper end of the first shell, and the locking cover plate is installed in the center of the top of the top plate. The first shell has an outwardly folded upper end snap-fit ​​structure, which snaps into the inner wall snap-fit ​​structure of the outer dustproof cylinder. The upper end of the second shell is inserted into the lower end of the first shell, and the second shell and the first shell are interference fit. The outer step of the second shell abuts against the inner wall snap-fit ​​of the outer dustproof cylinder, and the lower end slot of the second shell snaps into the compression buffer block.

[0011] The piston rod is a chrome-plated solid steel column, and threaded ends are provided at both ends of the piston rod. The threaded end face of the threaded end that connects to the double-layer upper support is provided with an internal hexagon countersunk hole.

[0012] The bottom of the bottom cover is welded with a lower lifting ring, and the lower bushing is interference-fitted into the through hole of the lower lifting ring.

[0013] The piston valve system and bottom valve system include a valve body and valve plates. The valve body has a throttling orifice and several stacked valve plates are press-fitted into the valve body.

[0014] The dust cover is a fiberglass plastic stamping part, the oil seal is a single spring skeleton rubber oil seal, and the guide is a flange block with steps and through holes, with a self-lubricating bushing installed in the through holes.

[0015] The rough structure includes protrusions, ribs, and bumps, with a height of 0.5~1mm.

[0016] The vibration isolation core includes a rubber flange block, a steel frame, and a steel baffle. The rubber flange block has a transversely penetrating inner hole, in which the steel frame is embedded. A steel baffle is installed at the bottom of the rubber flange block, and the inner hole of the steel baffle is conical.

[0017] The compression buffer block is a conical structure. The interior of the conical structure has a transverse through hole with ribs evenly distributed inside. The upper end of the conical structure has protrusions evenly distributed. The lower end surface of the conical structure near the dust cover has an external slot that engages with the inner wall buckle at the upper end of the inner dust cover. The lower end of the inner dust cover has ribs evenly distributed.

[0018] The piston rod is directly connected to the double-layer upper support by a locking nut. The locking nut is threaded to the piston rod. The end of the locking nut abuts against the upper end of the locking cover plate, and the locking cover plate abuts against the upper end of the top plate. An anti-loosening nylon ring is provided inside the locking nut.

[0019] The top plate has mounting holes evenly distributed along its edge, and several weight-reducing grooves are provided on its surface and back; the locking cover plate has a flange.

[0020] Compared with existing technologies, this utility model adopts a double-layer upper support structure made of stamped steel, combining the strength advantages of stamping process with the cost-effectiveness of steel. Compared with aluminum alloy, it reduces weight by 15% while increasing compressive strength by 30%. It avoids the use of complex reinforcing rib structures, reduces material costs, the difficulty of developing vibration dampers, and the difficulty of mold making for parts, while improving the overall performance and reliability of vibration dampers. The double dustproof cover with inner and outer layers reduces the amount of mud and sand intrusion to less than 20% of that of traditional structures, significantly extending the service life of the buffer block and oil seal, and improving the durability and dustproof performance of vibration dampers. This utility model is easy to maintain and disassemble, and has high adaptability. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of this utility model.

[0022] Figure 2 This is a cross-sectional view of the present invention.

[0023] Figure 3 for Figure 2 Enlarged view of point A.

[0024] Figure 4 This is a schematic diagram of the structure of the shock absorber assembly of this utility model.

[0025] Figure 5 This is a cross-sectional view of the shock absorber assembly of this utility model.

[0026] Figure 6 This is a cross-sectional view of the locking nut of this utility model.

[0027] Figure 7 This is a cross-sectional view of the housing of this utility model.

[0028] Figure 8 This is a cross-sectional view of the second housing of this utility model.

[0029] Figure 9 This is a cross-sectional view of the outer dustproof sleeve of this utility model.

[0030] Figure 10 This is a cross-sectional view of the inner dustproof sleeve of this utility model.

[0031] Figure 11 This is a cross-sectional view of the vibration isolation core of this utility model.

[0032] Figure 12 This is a cross-sectional view of the compression buffer block of this utility model.

[0033] Figure 13 This is a schematic diagram of the structure of the top plate surface of this utility model.

[0034] Figure 14 This is a structural schematic diagram of the back of the top plate of this utility model.

[0035] Figure 15 This is a cross-sectional view of the locking cover plate of this utility model. Detailed Implementation

[0036] The present invention will now be further described with reference to the accompanying drawings.

[0037] See Figure 1 , Figure 2 and Figure 3 This utility model is a lightweight vibration damper, including a vibration damper assembly, a double-layer upper support, a vibration isolation core, a compression buffer block, an outer dustproof sleeve, and an inner dustproof sleeve.

[0038] See Figure 4 , Figure 5The shock absorber assembly 1 is a twin-cylinder hydraulic shock absorber structure. The shock absorber assembly 1 includes a piston rod 1-1, a dust cover 1-2, an outer cylinder 1-3, an inner cylinder 1-4, an oil seal 1-5, a guide 1-6, a recovery buffer block 1-7, a recovery buffer block seat 1-8, a piston valve system 1-9, a bottom valve system 1-10, and a bottom cover 1-11. The outer cylinder 1-3 is a tubular structure that is thinner at the top and thicker at the bottom. The bottom cover 1-11 is welded to the bottom of the outer cylinder 1-3. The top edge of the outer cylinder 1-3 abuts against the end face of the oil seal 1-5. The dust cover 1-2 is interference-fitted onto the top of the outer cylinder 1-3. The inner cylinder 1-4 is located... Inside the outer cylinder 1-3, a bottom valve system 1-10 is installed between one end of the inner cylinder 1-4 and the bottom cover 1-11. A guide 1-6 is installed between the other end of the inner cylinder 1-4 and the oil seal 1-5. One end of the piston rod 1-1 is located inside the inner cylinder 1-4. The recovery buffer block seat 1-8 is sleeved and riveted to the outside of one end of the piston rod 1-1. The recovery buffer block 1-7 is installed on the recovery buffer block seat 1-8. A piston valve system 1-9 is installed at one end of the piston rod 1-1. The other end of the piston rod 1-1 passes through the guide 1-6, the oil seal 1-5, and the dust cover 1-2, and is connected to the double-layer upper support 2.

[0039] The piston rod 1-1 is a chrome-plated solid steel column. Both ends of the piston rod 1-1 are provided with threaded ends. The end face of the threaded end that connects to the double-layer upper support 2 is provided with an internal hexagon countersunk hole, which facilitates the disassembly and maintenance of the assembly and improves the maintainability of the shock absorber.

[0040] Dust covers 1-2 are made of fiberglass plastic stamping parts, protecting oil seals 1-5 from mud and sand corrosion.

[0041] The side of the dust cover 1-2 facing the compression buffer block 4 has a rough structure to prevent the compression buffer block 4 from colliding with the dust cover 1-2 and generating noise. The rough structure includes protrusions, ribs, and bumps, with a height of 0.5~1mm.

[0042] Oil seal 1-5 is a single-spring skeleton rubber oil seal, and guide 1-6 is a flange block with steps and through holes made by powder metallurgy, which serves to guide piston rod 1-1. A self-lubricating bushing is installed in the through hole of guide 1-6. The self-lubricating bushing is a bushing coated with a self-lubricating coating.

[0043] The outer cylinder 1-3 and inner cylinder 1-4 are filled with damper oil and a small amount of air. When the damper assembly 1 is working, the piston rod 1-1 reciprocates, causing the oil to flow in the outer cylinder 1-3 and inner cylinder 1-4. The oil generates damping force through the throttling orifices of the piston valve system 1-9 and the bottom valve system 1-10. The piston valve system 1-9 and the bottom valve system 1-10 include a valve body and valve plates. The valve body has a throttling orifice, and several stacked valve plates are press-fitted into the valve body.

[0044] The bottom of the bottom cover 1-11 is welded with a lower lifting ring 1-12, and the lower bushing 1-13 is interference-fitted into the through hole of the lower lifting ring 1-12. The lower bushing 1-13 is made of steel frame and rubber material and is used to connect with the vehicle body.

[0045] See Figure 3 The vibration isolation inner core 3 and the compression buffer block 4 are respectively sleeved on the piston rod 1-1. The vibration isolation inner core 3 is installed inside the double-layer upper support 2. The upper end of the compression buffer block 4 is embedded in the lower end of the double-layer upper support 2. The upper end of the outer dustproof sleeve 5 is connected to the double-layer upper support 2. The lower end of the outer dustproof sleeve 5 extends to the outside of the compression buffer block 4. The upper end of the inner dustproof sleeve 6 is connected to the compression buffer block 4. The lower end of the inner dustproof sleeve 6 extends to the outside of the vibration damper assembly 1.

[0046] The double-layer upper support 2 includes a first housing 2-1, a second housing 2-2, a top plate 2-3, and a locking cover plate 2-4. The top plate 2-3 is installed on the upper end of the first housing 2-1, and the locking cover plate 2-4 is installed at the center of the top of the top plate 2-3. Figure 7 , Figure 9 As shown, shell 2-1 has an outwardly folded upper end locking structure 2-1-1, which locks onto the inner wall locking structure 5-1 of the outer dustproof cylinder 5. The upper end of shell 2-2 is inserted into the lower end of shell 2-1, and shell 2-2 and shell 2-1 are interference-fitted. Shell 2-1 and shell 2-2 are stamped from steel sheets, and the two C-shaped stamped parts are spot-welded into an I-shaped cross-section, with 3 to 5 weld points evenly distributed at the welding position. The outer step of shell 2-2 abuts against the inner wall locking slot 5-2 of the outer dustproof cylinder 5, as shown. Figure 8 As shown, the lower end slot 2-2-1 of the housing 2-2 holds the compression buffer block 4.

[0047] The double-layer upper support 2 is an interference fit structure composed of housing 2-2 and housing 2-1. Housing 2-2 and housing 2-1 can be disassembled. After disassembly, the internal vibration isolation core 3 can be replaced to solve the problems of failure and abnormal noise after durability, improve the overall life of the shock absorber and reduce maintenance costs. At the same time, replacing the vibration isolation core 3 with one of different stiffness can adapt to cars with different loads, improve the comfort of the car, meet the replacement needs of different models and reduce the development cost of the shock absorber.

[0048] The piston rod 1-1 is directly connected to the double-layer upper support 2 using a locking nut 7. The locking nut 7 is threaded onto the piston rod 1-1. The end of the locking nut 7 abuts against the upper end of the locking cover plate 2-4, and the locking cover plate 2-4 abuts against the upper end of the top plate 2-3. Figure 6 As shown, the locking nut 7 has an anti-loosening nylon ring 7-1 inside to prevent the locking nut 7 from loosening.

[0049] See Figure 11The vibration isolation core 3 includes a rubber flange block 3-1, a steel frame 3-2, and a steel baffle 3-3. The rubber flange block 3-1 has a transverse through-hole, and the steel frame 3-2 is embedded in the through-hole. The steel baffle 3-3 is installed at the bottom of the rubber flange block 3-1. The inner hole of the steel baffle 3-3 is tapered and is used for the installation and positioning of the steel baffle 3-3 at the end of the piston rod 1-1.

[0050] See Figure 10 , Figure 12 The compression buffer block 4 is a conical structure made of high-performance polyurethane material. The conical structure has a transverse through hole inside, and ribs 4-2 are evenly distributed inside the through hole. The upper end of the conical structure has protrusions 4-3 evenly distributed. The lower end surface of the conical structure near the dust cover 1-2 has an external slot 4-1. The external slot 4-1 locks the inner wall buckle 6-1 at the upper end of the inner dust cover 6. Ribs 6-2 are evenly distributed on the lower end of the inner dust cover 6.

[0051] Since the compression buffer block 4 needs to be engaged with the inner dustproof sleeve 6, the stability of the compression buffer block 4 on the double-layer upper support 2 needs to be strengthened to prevent the compression buffer block 4 from falling off. The first rib 4-2 is interference-fitted with the piston rod 1-1, which improves the stability of the connection and avoids friction noise with the piston rod 1-1. The protrusion 4-3 can prevent friction noise between the compression buffer block 4 and the bottom of the second housing 2-2. The second rib 6-2 can prevent friction noise between the inner dustproof sleeve 6 and the outer cylinder 1-3.

[0052] See Figure 13 , Figure 14 The top plate 2-3 is made of cast aluminum. The edge of the top plate 2-3 is evenly distributed with mounting holes 2-3-1 for connecting with the vehicle body. The surface and back of the top plate 2-3 are provided with several weight reduction grooves 2-3-2.

[0053] See Figure 15 The locking cover plate 2-4 is provided with a flange 2-4-1 to increase strength.

[0054] The assembly process of the lightweight vibration damper includes the following steps: Step 1, after the arc-shaped curved surface forming and laser trimming of shell 1 and shell 2, the upper and lower stamped parts are uniformly spot-welded around the periphery. During the stamping process, uniformly distributed welding concave points are formed to facilitate welding positioning. After carburizing at 920℃, they are directly transferred to a 260℃ nitrate salt bath for graded quenching. When the surface hardness reaches HRC58-62, the core maintains HRC32-35. The coaxiality tolerance of the upper and lower stamped parts is ≤0.1mm, and the perpendicularity of the installation reference surface of the outer dustproof sleeve to the piston rod axis is ≤0.1°. Step 2, the snap-fitting of the inner dustproof sleeve and the compression buffer block, the snap-fitting of the compression buffer block and shell 2 are completed in sequence, the outer dustproof sleeve is installed on the double-layer upper support, and the double-layer upper support, vibration isolation inner core, outer dustproof sleeve, and compression buffer block are assembled on the piston rod with an interference fit of 0.02-0.05mm.

[0055] After assembly, the dustproof performance was verified by spraying quartz sand with a particle size of 0.1-0.3mm at 80kPa air pressure. The residual quartz sand at the oil seal and the recessed part of the compression buffer block was significantly reduced.

[0056] This utility model adopts a double-layer upper support structure made of stamped steel, combining the strength advantages of stamping technology with the cost-effectiveness of steel. Compared with aluminum alloy, it reduces weight by 15% while increasing compressive strength by 30%. It avoids the use of complex reinforcing rib structures, reduces material costs, the difficulty of developing vibration dampers, and the difficulty of mold making for parts, while improving the overall performance and reliability of vibration dampers. The double dustproof cover with inner and outer layers reduces the amount of mud and sand intrusion to less than 20% of that of traditional structures, significantly extending the service life of the buffer block and oil seal, and improving the durability and dustproof performance of the vibration damper. This utility model is easy to maintain and disassemble, and has high adaptability.

Claims

1. A lightweight vibration damper, comprising a vibration damper assembly, a double-layer upper support, a vibration isolation core, a compression buffer block, an outer dustproof sleeve, and an inner dustproof sleeve, characterized in that: The shock absorber assembly (1) is a twin-cylinder hydraulic shock absorber structure. The shock absorber assembly (1) includes a piston rod (1-1), a dust cover (1-2), an outer cylinder (1-3), an inner cylinder (1-4), an oil seal (1-5), a guide (1-6), a recovery buffer block (1-7), a recovery buffer block seat (1-8), a piston valve system (1-9), a bottom valve system (1-10), and a bottom cover (1-11). The outer cylinder (1-3) is a tubular structure that is thinner at the top and thicker at the bottom. A bottom cover is welded to the bottom of the outer cylinder (1-3). 1-11), the top rolled edge structure of the outer cylinder (1-3) abuts against the end face of the oil seal (1-5), the dust cover (1-2) is interference-fitted onto the top of the outer cylinder (1-3), the inner cylinder (1-4) is located inside the outer cylinder (1-3), a bottom valve system (1-10) is installed between one end of the inner cylinder (1-4) and the bottom cover (1-11), a guide (1-6) is installed between the other end of the inner cylinder (1-4) and the oil seal (1-5), and one end of the piston rod (1-1) is located in the inner cylinder (1-11). 4) Inside, the recovery buffer block seat (1-8) is fitted and riveted to one end of the piston rod (1-1). The recovery buffer block (1-7) is installed on the recovery buffer block seat (1-8). A piston valve system (1-9) is installed at one end of the piston rod (1-1). The other end of the piston rod (1-1) passes through the guide (1-6), oil seal (1-5), and dust cover (1-2) and is connected to the double-layer upper support (2). The vibration isolation inner core (3) and the compression buffer block (4) are respectively fitted outside the piston rod (1-1). The vibration isolation core (3) is installed inside the double-layer upper support (2). The upper end of the compression buffer block (4) is embedded in the lower end of the double-layer upper support (2). The upper end of the outer dustproof sleeve (5) is connected to the double-layer upper support (2). The lower end of the outer dustproof sleeve (5) extends to the outside of the compression buffer block (4). The upper end of the inner dustproof sleeve (6) is connected to the compression buffer block (4). The lower end of the inner dustproof sleeve (6) extends to the outside of the damper assembly (1). The side of the dust cover (1-2) facing the compression buffer block (4) has a rough structure. The double-layer upper support (2) includes a first shell (2-1), a second shell (2-2), a top plate (2-3), and a locking cover plate (2-4). The top plate (2-3) is installed on the upper end of the first shell (2-1), and the locking cover plate (2-4) is installed in the center of the top of the top plate (2-3). The first shell (2-1) has an outwardly folded upper end snap-fit ​​structure (2-1-1). The upper end snap-fit ​​structure (2-1-1) snaps into the inner wall snap-fit ​​structure (5-1) of the outer dustproof cylinder (5). The upper end of the second shell (2-2) is inserted into the lower end of the first shell (2-1), and the second shell (2-2) and the first shell (2-1) are interference fit. The outer step of the second shell (2-2) abuts against the inner wall snap-fit ​​(5-2) of the outer dustproof cylinder (5), and the lower end slot (2-2-1) of the second shell (2-2) snaps into the compression buffer block (4).

2. The lightweight vibration damper according to claim 1, characterized in that: The piston rod (1-1) is a chrome-plated solid steel column. Both ends of the piston rod (1-1) are respectively provided with threaded ends. The threaded end face of the connection to the double-layer upper support (2) is provided with an internal hexagon countersunk hole.

3. A lightweight vibration damper according to claim 1, characterized in that: The bottom of the bottom cover (1-11) is welded with a lower lifting ring (1-12), and the lower bushing (1-13) is interference-fitted into the through hole of the lower lifting ring (1-12).

4. A lightweight vibration damper according to claim 1, characterized in that: The piston valve system (1-9) and bottom valve system (1-10) include a valve body and valve plates. The valve body has a throttling orifice and several stacked valve plates are press-fitted into the valve body.

5. A lightweight vibration damper according to claim 1, characterized in that: The dust cover (1-2) is a glass fiber plastic stamping part, the oil seal (1-5) is a single spring skeleton rubber oil seal, and the guide (1-6) is a flange block with steps and through holes, with a self-lubricating bushing installed in the through hole.

6. A lightweight vibration damper according to claim 1, characterized in that: The rough structure includes protrusions, ribs, and bumps, with a height of 0.5~1mm.

7. A lightweight vibration damper according to claim 1, characterized in that: The vibration isolation core (3) includes a rubber flange block (3-1), a steel frame (3-2), and a steel baffle (3-3). The rubber flange block (3-1) has a transverse through hole, and the steel frame (3-2) is embedded in the hole. The bottom of the rubber flange block (3-1) is equipped with a steel baffle (3-3), and the inner hole of the steel baffle (3-3) is conical.

8. A lightweight vibration damper according to claim 1, characterized in that: The compression buffer block (4) is a conical structure. The conical structure has a transverse through hole inside. The through hole is evenly distributed with ribs (4-2). The upper end of the conical structure is evenly distributed with protrusions (4-3). The lower end surface of the conical structure near the dust cover (1-2) is provided with an external slot (4-1). The external slot (4-1) locks the inner wall buckle (6-1) at the upper end of the inner dust cover (6). The lower end of the inner dust cover (6) is evenly distributed with ribs (6-2).

9. A lightweight vibration damper according to claim 1, characterized in that: The piston rod (1-1) and the double-layer upper support (2) are directly connected by a locking nut (7). The locking nut (7) is threadedly connected to the piston rod (1-1). The end of the locking nut (7) abuts against the upper end of the locking cover plate (2-4). The locking cover plate (2-4) abuts against the upper end of the top plate (2-3). The locking nut (7) is provided with an anti-loosening nylon ring (7-1) inside.

10. A lightweight vibration damper according to claim 1, characterized in that: The top plate (2-3) has mounting holes (2-3-1) evenly distributed along its edge. The top plate (2-3) has several weight-reducing grooves (2-3-2) on its surface and back. The locking cover plate (2-4) has a flange (2-4-1).

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