A hanger shaft assembly and a container
By installing sleeves and limiting components for the lifting rods on the container underframe, and cooperating with the locking grooves, the problems of retraction and displacement of the lifting shaft structure during lifting are solved, achieving stable locking of the lifting rods and improving the safety and ease of operation of container lifting.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SHANGHAI SINGAMAS INTEGRATED EQUIP CO LTD
- Filing Date
- 2025-07-23
- Publication Date
- 2026-07-14
AI Technical Summary
In the existing technology, the lifting shaft structure is prone to retracting into the box due to collision during hoisting and use, requiring manual extraction. Furthermore, the lifting shaft shifts during hoisting, making operation difficult and posing safety hazards.
A sleeve and a boom are installed on the container underframe. The boom has a limiting component that engages with a locking groove on the sleeve to form a locking position, limiting the relative position of the boom and the sleeve and ensuring the boom is stable when it is pulled out. The boom is stably locked by the engagement of the limiting component and the locking groove.
The boom remains stable when extended, and the operation is simple. Only one boom extension operation is required before container lifting, which improves the safety and stability of the lifting process.
Smart Images
Figure CN224492282U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of container technology, and in particular to a lifting shaft assembly and a container. Background Technology
[0002] Container shipping is an important mode of transportation in the cargo transportation process. Container shipping has advantages such as high standardization, good sealing, large scale, low cost, and high quality, improving the safety and efficiency of cargo transportation. Currently, containers are increasingly being used in the new energy field, such as energy storage containers. Energy storage containers often house a large number of battery clusters, resulting in significant weight. To transport heavy containers (such as energy storage containers, electrical equipment boxes, etc.), existing technologies use lifting shafts on both sides of the container's bottom frame. Lifting devices are connected to these shafts via ropes to lift the container. However, the inventors of this case have discovered that the existing lifting shaft structure requires manual pre-extraction during lifting. This often results in the shaft retracting back into the container due to collisions or other reasons, requiring manual retraction. The retraction state of the shaft is uncontrollable, and the shaft may also shift during lifting, making lifting difficult and posing certain safety hazards.
[0003] Therefore, improvements to existing technologies are necessary. Utility Model Content
[0004] This application aims to solve at least one of the technical problems existing in the prior art by providing a lifting shaft assembly and a container. The container base frame is provided with a sleeve and a lifting rod. The lifting rod can move relative to the sleeve along its axial direction. On the movement path of the lifting rod, a limiting member provided on the lifting rod cooperates with a first snap-fit groove provided on the sleeve to form a snap-fit positioning, which restricts the relative position between the lifting rod and the sleeve. This ensures that the lifting rod remains stable when it is pulled out, and the lifting rod will not retract into the sleeve due to external force collision. The operation is simple, and only one lifting rod pull-out operation is required before container lifting. Furthermore, the stability of the lifting rod can be guaranteed during container lifting, thus improving the safety of container lifting.
[0005] According to one aspect of this application, a lifting shaft assembly is provided for use in a container. The lifting shaft assembly is located on the container's underframe and includes a sleeve and a lifting rod. The sleeve is fixed to the underframe. The lifting rod is housed in the sleeve, wherein one end of the lifting rod is provided with a limiting member, and the sleeve is provided with a first engaging groove corresponding to the limiting member. When the lifting rod is partially withdrawn from the sleeve and the limiting member is housed in the first engaging groove, the lifting rod is in a withdrawn state relative to the container.
[0006] In one embodiment, the sleeve is further provided with a guide groove, which communicates with the first snap-fit groove. The first snap-fit groove is located on one side of the guide groove in the circumferential direction of the sleeve. When the rod portion is pulled out of the sleeve, the limiting member slides along the guide groove to one side of the first snap-fit groove.
[0007] In one embodiment, the guide groove extends along the axial direction of the sleeve, and the sleeve is further provided with a second snap-fit groove. The first snap-fit groove and the second snap-fit groove are respectively disposed at both ends of the guide groove in the axial direction of the sleeve.
[0008] In one embodiment, a baffle is further included, the baffle being disposed at the end of the boom away from the base frame; a projection plane λ perpendicular to the axial direction of the sleeve is defined, and the orthographic projection portion of the baffle on the projection plane λ is located outside the orthographic projection of the sleeve on the projection plane λ.
[0009] In one embodiment, the orthographic projection shape of the baffle on the projection plane λ is teardrop-shaped or gourd-shaped.
[0010] In one embodiment, a handle is also included, the handle being fixed to the side of the baffle away from the boom.
[0011] In one embodiment, one end of the sleeve is flush with the outer wall of the base frame, and the other end is located inside the base frame.
[0012] In one embodiment, both the sleeve and the boom are cylindrical.
[0013] According to another aspect of this application, a container is provided, including any of the aforementioned lifting shaft assemblies, with at least two of the lifting shaft assemblies disposed on opposite sides of the underframe.
[0014] The beneficial effects of this application are: the boom can move relative to the sleeve along the axial direction; on the movement path of the boom, the limiting piece set on the boom and the first snap-fit groove set on the sleeve cooperate with each other to form a snap-fit positioning, which restricts the relative position between the boom and the sleeve, ensuring that the boom remains stable when it is pulled out, and the boom will not retract into the sleeve due to external force. The operation is simple, and only one boom pull-out operation is required before container lifting. Moreover, the stability of the boom can be guaranteed during container lifting, thus improving the safety of container lifting. Attached Figure Description
[0015] The technical solution and other beneficial effects of this application will become apparent from the following detailed description of specific embodiments in conjunction with the accompanying drawings.
[0016] Figure 1 This is a side view of a container provided in an embodiment of this application.
[0017] Figure 2 This is a schematic diagram of a base frame and hanging shaft assembly provided in an embodiment of this application.
[0018] Figure 3 This is a schematic diagram of a boom being pulled out, provided in an embodiment of this application.
[0019] Figure 4 This is a schematic diagram of a boom not being pulled out, provided in an embodiment of this application.
[0020] Figure 5 yes Figure 4 The left view.
[0021] In the picture:
[0022] 10. Hanger shaft assembly; 11. Sleeve; 111. First locking groove; 112. Guide groove; 113. Second locking groove; 12. Hanger rod; 121. Limiting component; 13. Baffle; 14. Handle;
[0023] 20. Container; 21. Base frame; 211. Bottom side beam; 2111. Outer side wall; 2112. Inner side wall. Detailed Implementation
[0024] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.
[0025] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.
[0026] The lifting shaft assembly and container of this application will be described in detail below with reference to the accompanying drawings and specific embodiments.
[0027] The inventors of this case discovered that in the existing technology, the lifting shaft structure needs to be manually pulled out in advance during hoisting and use. However, the pulled-out lifting shaft is prone to retracting back into the box due to collisions or other reasons, requiring manual re-pulling. The retraction state of the lifting shaft cannot be controlled, and the lifting shaft will also shift during the hoisting process, which not only makes the hoisting operation difficult but also poses certain safety hazards.
[0028] To address the aforementioned technical problems, this application provides a lifting shaft assembly applied to a container. The lifting shaft assembly is located on the container's underframe and includes a sleeve and a lifting rod. The sleeve is fixed to the underframe. The lifting rod is housed within the sleeve, wherein one end of the lifting rod is provided with a limiting member, and the sleeve is provided with a first engaging groove corresponding to the limiting member. When the lifting rod is partially withdrawn from the sleeve and the limiting member is housed within the first engaging groove, the lifting rod is in a withdrawn state relative to the container.
[0029] Specifically, the container in this embodiment can be an overweight container, an energy storage container, a data center container, etc. A sleeve and a boom are provided on the container's underframe. The boom can move relative to the sleeve along its axial direction. During the boom's movement path, a limiting component on the boom cooperates with a first locking groove on the sleeve to form a locking position, restricting the relative position between the boom and the sleeve. This ensures the boom remains stable when extended, preventing it from retracting into the sleeve due to external impact. The operation is simple; only one boom extension operation is needed before container lifting. Furthermore, the boom's stability is guaranteed during container lifting, improving the safety of container lifting. This will be elaborated in detail below.
[0030] See Figure 1 and Figure 2 The lifting shaft assembly 10 is applied to the container 20. The lifting shaft assembly 10 is located on the underframe 21 of the container 20 and includes a sleeve 11 and a lifting rod 12. The sleeve 11 is fixed to the underframe 21. The lifting rod 12 is housed in the sleeve 11. One end of the lifting rod 12 is provided with a limiting member 121. The sleeve 11 is provided with a first engaging groove 111 corresponding to the limiting member 121. When the lifting rod 12 is partially pulled out from the sleeve 11 and the limiting member 121 is housed in the first engaging groove 111, the lifting rod 12 is in a pulled-out state relative to the container 20.
[0031] The boom 12 can move relative to the sleeve 11 along the axial direction. During the process of pulling out the boom 12, the limiting member 121 on the boom 12 and the first snap-fit groove 111 on the sleeve 11 cooperate with each other to form a snap-fit positioning, which restricts the relative position between the boom 12 and the sleeve 11. This ensures that the boom 12 remains stable (locked state) when it is pulled out. The boom 12 will not retract into the sleeve 11 due to external force before the container 20 is lifted. The operation is simple. Only one boom 12 pulling out and locking operation is required before the container 20 is lifted. During the lifting of the container 20, the position of the boom 12 can be kept stable, without coming out or retracting, which improves the safety of the container 20 lifting.
[0032] During the lifting operation of container 20, the boom 12 is first pulled out of the sleeve 11 until the limiting piece 121 engages with the first locking groove 111. The relative position of the boom 12 with the container 20 (sleeve 11) in the axial direction of the sleeve 11 will not change (i.e., the boom 12 will not retract into the sleeve 11). Then, the boom 12 is connected to the lifting rope to realize the lifting of container 20. Since the lifting shaft assembly 10 is set on the base frame 21 of container 20, during the lifting process of container 20, the lifting rope used for lifting extends from the bottom of container 20 to the top of container 20. The lifting rope has a certain limiting effect on container 20, which can ensure the stability of container 20 during the lifting process, thereby improving the safety of lifting.
[0033] It should be noted that when the boom 12 is pulled outward toward the container 20, only part of the boom 12 should be pulled out of the sleeve 11, while another part of the boom 12 should remain inside the sleeve 11 to prevent the boom 12 from falling out of the sleeve 11. The boom 12 being in the pulled-out state means that the boom 12 is in the use state, that is, the boom 12 is temporarily fixed after being pulled out of the sleeve 11 and will not retract.
[0034] In some embodiments, the sleeve 11 is further provided with a guide groove 112, which communicates with the first snap-fit groove 111. The first snap-fit groove 111 is located on one side of the guide groove 112 in the circumferential direction of the sleeve 11. When the lifting rod 12 is partially pulled out of the sleeve 11, the limiting member 121 slides along the guide groove 112 to one side of the first snap-fit groove 111.
[0035] The guide groove 112 guides the limiting member 121 into the first engaging groove 111, enabling the limiting member 121 to engage with the first engaging groove 111. Simultaneously, it limits the length of the lifting rod 12 that can be extended, preventing excessive extension of the lifting rod 12. When a large portion of the lifting rod 12 is extended, it is prone to deformation under stress, which is detrimental to lifting safety. Furthermore, since the lifting shaft assembly 10 is mounted on the base frame 21 and the first engaging groove 111 is located at the bottom of the container, the specific location of the first engaging groove 111 is not visible before the container 20 is lifted. In this embodiment, the guide groove 112 ensures that the limiting member 121 can smoothly enter the first engaging groove 111, simplifying the operation.
[0036] It should be noted that the first locking groove 111 is located on the side of the guide groove 112 facing the circumferential direction of the sleeve 11. When the limiting member 121 slides along the guide groove 112 to the position corresponding to the first locking groove 111, the boom 12 needs to be rotated at a certain angle so that the limiting member 121 can be locked in the first locking groove 111 (similarly, after the container 20 is hoisted, the boom 12 needs to be rotated at a certain angle to release the locking state between the limiting member 121 and the first locking groove 111). This can prevent the limiting member 121 from slipping out of the first locking groove 111, thus improving the stability of the boom 12 when it is in the withdrawn state.
[0037] It is worth mentioning that in this embodiment, the limiting member 121 is a protrusion provided on the lifting rod 12, which has a simple structure and is easy to use; the guide groove 112 extends along the axial direction of the sleeve 11. In some embodiments, the guide groove 112 can also be spirally arranged, and it is not limited to this, as long as it can guide the limiting member 121 into the first snap-fit groove 111.
[0038] In some embodiments, the first snap-fit groove 111 is disposed at the end of the guide groove 112 (e.g., Figure 2 As shown, the first engaging groove 111 is located at the left end of the guide groove 112. During the process of pulling the boom 12 outward, the limiting member 121 moves in the guide groove 112 until it abuts against the end of the guide groove 112 (the boom 12 can no longer be pulled out). At this time, the boom 12 is rotated to engage the limiting member 121 in the first engaging groove 111. With this configuration, during the process of pulling the boom 12 outward, when the boom 12 can no longer be pulled out, it can be determined that the limiting member 121 is opposite to the first engaging groove 111. Rotating the boom 12 can achieve the engagement of the limiting member 121 with the first engaging groove 111, which is simple to operate.
[0039] In this embodiment, the limiting member 121 is disposed at the end of the boom 12. In some embodiments, the limiting member 121 may also be disposed in the middle part of the boom 12, that is, when the limiting member 121 is engaged in the first engaging groove 111, a portion of the boom 12 is still accommodated in the sleeve 11 (the portion of the sleeve 11 that the limiting member 121 passes through during its sliding process). Figure 3 From the perspective of the sleeve 11 located in the part to the right of the first clamping groove 111, even if part of the boom 12 is pulled out (away from the bottom frame 21 of the container 20), there is still a sufficient length of boom 12 to support the container 20 at the bottom of the container 20, which helps to keep the container 20 stable during the hoisting process.
[0040] In some embodiments, the guide groove 112 extends along the axial direction of the sleeve 11, and the sleeve 11 is further provided with a second snap-fit groove 113. The first snap-fit groove 111 and the second snap-fit groove 113 are respectively disposed at both ends of the guide groove 112 in the axial direction of the sleeve 11.
[0041] The first locking groove 111 is used for fixing and limiting the boom 12 when it is in the withdrawn state, and the second locking groove 113 is used for fixing and limiting the boom 12 when it is not withdrawn; specifically, the limiting member 121 is initially locked in the second locking groove 113, at which time the boom 12 is housed in the sleeve 11 and has not been withdrawn (e.g., Figure 4 (As shown); When container 20 needs to be hoisted, rotate boom 12 so that limit member 121 enters guide groove 112 from second engagement groove 113, pull boom 12 outward until boom 12 is pulled to the set length (limit member 121 moves to the position corresponding to first engagement groove 111), rotate boom 12, limit member 121 engages in first engagement groove 111, boom 12 is in the withdrawn state, and then the hoisting operation of container 20 is carried out; in container 2 After hoisting is completed, rotate the boom 12. The limiting piece 121 separates from the first locking groove 111, the pulled-out state of the boom 12 is released, and the boom 12 resets (retracts into the container 20) until the limiting piece 121 corresponds to the second locking groove 113. Rotate the boom 12 so that the limiting piece 121 engages in the second locking groove 113, ensuring that the boom 12 is in a stable state when not in use. During transportation, the boom 12 will not slip out of the sleeve 11, ensuring transportation safety.
[0042] It is worth mentioning that in some embodiments, the second locking groove 113 may not be provided, or the second locking groove 113 and the first locking groove 111 may not be located on the same side. When the lifting rod 12 is not pulled out, the limiting member 121 is located on the right side of the sleeve 11. Figure 3 (View perspective), the limiting member 121 abuts against the end of the sleeve 11, which can also limit the rod 12 (limiting it when it is not pulled out), but is not limited to this.
[0043] In some embodiments, the suspension shaft assembly 10 further includes a baffle 13, which is disposed at the end of the suspension rod 12 away from the base frame 21; a projection plane λ perpendicular to the axial direction of the sleeve 11 is defined, and the orthographic projection portion of the baffle 13 on the projection plane λ is located outside the orthographic projection of the sleeve 11 on the projection plane λ (e.g., Figure 5 (As shown).
[0044] By setting the baffle 13, the lifting rod 12 can be prevented from retracting into the sleeve 11, thus improving the convenience of use. In some embodiments, the orthographic projection shape of the baffle 13 on the projection plane λ is teardrop-shaped or gourd-shaped, which can directly determine from the appearance of the baffle 13 whether the lifting rod 12 is in the locked state (the lifting rod 12 cannot move in the axial direction of the sleeve 11, that is, the limiting member 121 cooperates with the first locking groove 111, or in some embodiments the limiting member 121 cooperates with the second locking groove 113) or the unlocked state (the lifting rod 12 can move freely in the axial direction of the sleeve 11), thus preventing the lifting rod 12 from being lifted in the unlocked state and eliminating potential safety hazards.
[0045] In some embodiments, the baffle 13 can also be a rhombus shape, or even a circle in some embodiments. A pointing protrusion is provided on the surface of the circular baffle 13, which can also reflect whether the boom 12 is in a locked or unlocked state. This is not limited to this.
[0046] In some embodiments, the lifting shaft assembly 10 further includes a handle 14, which is fixed to the side of the baffle 13 away from the lifting rod 12. The handle 14 facilitates the removal of the lifting rod 12, and has a simple structure and is easy to use.
[0047] In some embodiments, one end of the sleeve 11 is flush with the outer wall 2111 of the base frame 21, and the other end is located inside the base frame 21. The sleeve 11 is flush with the outer wall 2111, that is, the sleeve 11 penetrates the base frame 21 (penetrates the bottom edge beam 211 of the container 20, and the bottom edge beam 211 has an outer wall 2111 and an inner wall 2112 oppositely arranged in the axial direction of the sleeve 11). During installation, the sleeve 11 needs to be welded to the bottom edge beam 211 (the sleeve 11 needs to be welded to both the outer wall 2111 and the inner wall 2112), which further improves the connection strength.
[0048] In some embodiments, the end of the sleeve 11 can also abut against the inner sidewall 2112. In this way, only the sleeve 11 and the inner sidewall 2112 need to be welded, which reduces the number of welding operations and improves assembly efficiency. Moreover, the sleeve 11 does not need to be welded to the outer sidewall 2111, so there will be no welding slag on the outer sidewall 2111, and the outer sidewall 2111 is flatter and more aesthetically pleasing.
[0049] In some embodiments, both the sleeve 11 and the boom 12 are cylindrical. To ensure that the boom 12 can be smoothly pulled out of the sleeve 11, the diameter of the boom 12 is smaller than the diameter of the sleeve 11. When the sleeve 11 (and the boom 12) are cylindrical, the stress distribution is more uniform, there are no stress concentration points, it is not easy to deform, and it has strong bending resistance. During the lifting of the container 20, the boom 12 is not easy to deform or bend, which improves the safety of the lifting.
[0050] It is worth mentioning that the first locking groove 111 should be set on the bottom semicircle of the sleeve 11 (a reference plane parallel to the horizontal plane crosses the sleeve 11, the part of the sleeve 11 below the reference plane is the bottom semicircle, and the part above the reference plane is the top semicircle), that is, set below the guide groove 112; when the first locking groove 111 is set on the top semicircle (set above the guide groove 112), the limiting member 121 may detach from the first locking groove 111 under the action of gravity, and the locking state between the first locking groove 111 and the limiting member 121 is unstable, which is not conducive to the stability of the rod 12 in the withdrawn state.
[0051] In some embodiments, the sleeve 11 may be cylindrical, and the lifting rod 12 may be non-cylindrical, for example, the cross-section (the surface perpendicular to the axial direction of the lifting rod 12) of the lifting rod 12 may be square; the sleeve 11 and the lifting rod 12 may also be other shapes, which can ensure that the lifting rod 12 can move along the axial direction of the sleeve 11, and the lifting rod 12 can rotate around the axial direction of the sleeve 11 in the sleeve 11. During the rotation of the lifting rod 12, the limiting member 121 can be engaged with the first snap-fit groove 111. Shapes similar to the above schemes are all within the protection scope of this application.
[0052] On the other hand, this application also relates to a container 20, including any of the aforementioned lifting shaft assemblies 10, with at least two lifting shaft assemblies 10 disposed on opposite sides of the base frame 21.
[0053] Using the technical solution provided in this application embodiment, the boom 12 can move relative to the sleeve 11 along the axial direction. On the movement path of the boom 12, the limiting member 121 provided on the boom 12 and the first snap-fit groove 111 provided on the sleeve 11 cooperate with each other to form a snap-fit positioning, which restricts the relative position between the boom 12 and the sleeve 11. This ensures that the boom 12 remains stable when it is pulled out, and the boom 12 will not retract into the sleeve 11 due to external force collision. The operation is simple, and only one boom 12 pull-out operation is required before the container 20 is hoisted. Moreover, the stability of the boom 12 can be ensured during the hoisting of the container 20, thus improving the safety of the container 20 hoisting.
[0054] In the various embodiments of this application, unless otherwise specified or logically conflicting, the terminology or descriptions between different embodiments are consistent and can be referenced mutually. Technical features in different embodiments can be combined to form new embodiments based on their inherent logical relationships. In this application, "at least one" means one or more, and "more than one" means two or more.
[0055] It is understood that the various numerical designations used in the embodiments of this application are merely for descriptive convenience and are not intended to limit the scope of the embodiments of this application. The order of the process numbers described above does not imply the order of execution; the execution order of each process should be determined by its function and internal logic.
[0056] The above provides a detailed description of the lifting shaft assembly and container provided in the embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand this application and its core ideas. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.
Claims
1. A lifting shaft assembly, characterized in that, Applied to containers, the lifting shaft assembly is located on the container underframe and includes: The sleeve is fixed to the base frame; A boom is housed in the sleeve, wherein one end of the boom is provided with a limiting member, and the sleeve is provided with a first snap-fit groove corresponding to the limiting member; when the boom is partially pulled out of the sleeve and the limiting member is housed in the first snap-fit groove, the boom is in a pulled-out state relative to the container.
2. The lifting shaft assembly as described in claim 1, characterized in that, The sleeve is also provided with a guide groove, which is connected to the first snap-fit groove, and the first snap-fit groove is located on one side of the guide groove in the circumferential direction of the sleeve. When the boom section is pulled out of the sleeve, the limiting member slides along the guide groove to one side of the first snap-fit groove.
3. The lifting shaft assembly as described in claim 2, characterized in that, The guide groove extends along the axial direction of the sleeve, and the sleeve is also provided with a second snap-fit groove. The first snap-fit groove and the second snap-fit groove are respectively disposed at both ends of the guide groove in the axial direction of the sleeve.
4. The lifting shaft assembly as described in claim 1, characterized in that, It also includes a baffle plate disposed at the end of the boom away from the base frame; A projection plane λ is set perpendicular to the axial direction of the sleeve, and the orthographic projection portion of the baffle on the projection plane λ is located outside the orthographic projection of the sleeve on the projection plane λ.
5. The lifting shaft assembly as described in claim 4, characterized in that, The shape of the baffle projected onto the projection plane λ is teardrop-shaped or gourd-shaped.
6. The lifting shaft assembly as described in claim 4, characterized in that, It also includes a handle, which is fixed to the side of the baffle away from the boom.
7. The lifting shaft assembly as described in claim 1, characterized in that, One end of the sleeve is flush with the outer wall of the base frame, and the other end is located inside the base frame.
8. The lifting shaft assembly as described in claim 1, characterized in that, Both the sleeve and the hanger rod are cylindrical.
9. A container, characterized in that, It includes at least two lifting shaft assemblies as described in any one of claims 1 to 8, with at least two of the lifting shaft assemblies disposed on opposite sides of the base frame.