Inclined tunnel jacking support installation machine and installation method

Abstract

The present invention relates to the field of coal mine machinery technology, and in particular to an inclined tunnel jacking support installation machine and installation method. The inclined tunnel jacking support installation machine includes: a track, a carrier and a drive device; the track is laid in the inclined tunnel, the carrier includes a first trolley and a heavy vehicle, and the heavy vehicle is installed on the track; the drive device includes a first drive device and a second drive device, the first drive device drives the first trolley to move in the inclined tunnel, and the first trolley is provided with a jacking mechanism for fixing the first trolley; the second drive device is used to drive the heavy vehicle to move on the track, and the heavy vehicle is provided with a column lifting mechanism for clamping the jacking support. The installation machine of the present invention solves the problem of inclined tunnel support installation, reduces labor intensity, improves support installation efficiency, ensures the personal safety of workers, and reduces labor costs.

Description

Technical Field

[0001] The present invention relates to the technical field of coal mine machinery, and in particular to an inclined tunnel jacking support installation machine and an installation method. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to those skilled in the art.

[0003] In recent years, with the increasing centralization, large-scale, mechanization, and automation of mines, many new and expanded mines, including large mines with deeper mining depths, have tended to adopt inclined shaft development methods. However, inclined shafts are affected by the high inclination angle of coal seams. Coupled with the often complex geodetic conditions in coal mining areas, various safety issues frequently arise in coal seam mining operations. To minimize the occurrence of such issues, the support of inclined tunnels is particularly important.

[0004] In the mid-to-late 20th century, metal supports for tunnels developed rapidly. They can well support soft and broken rock, adapt to the deformation of surrounding rock or coal, and ensure the stability of tunnels, making them the main form of mine tunnel support.

[0005] The jacking support is a retractable component made of a hollow steel pipe filled with concrete. It has strong load-bearing capacity and anti-deformation ability. It is suitable for tunnels with an inclination angle between 25° and 30° and occasions with high support difficulties.

[0006] Due to the limited space in the tunnel, large mechanical equipment cannot be used. The weight of an empty jacking support is about 300kg. Manual installation of the jacking support is not only labor-intensive, with a harsh working environment and low efficiency, but also seriously threatens the personal safety of workers. Patent CN202010274746.7 (Announcement No. CN 111425216 B) discloses a composite support structure, construction system and method. Although the steel pipe construction device therein can replace manual labor to a certain extent, the device is mainly used for the installation of arch supports. The synchronization between the erection of the support and the grouting is poor, the required working space is large, the construction machinery is complex, and the device is prone to overturning and instability when installing supports in inclined tunnels. Summary of the Invention

[0007] In view of the shortcomings of the existing technology, the purpose of the embodiments of the present invention is to provide an inclined tunnel jacking support installation machine to solve the problem of support installation in inclined tunnels, thereby further solving the problems of low efficiency, poor safety, high labor costs, etc. in the installation process.

[0008] In order to achieve the above objectives, the embodiments of the present invention provide the following technical solutions:

[0009] A machine for installing a jacking support in an inclined tunnel comprises: a track, a carrier and a driving device; the track is laid in an inclined tunnel, the carrier comprises a first trolley and a heavy vehicle, and the heavy vehicle is installed on the track; the driving device comprises a first driving device and a second driving device, the first driving device drives the first trolley to move in the inclined tunnel, and the first trolley is provided with a jacking mechanism for fixing the first trolley; the second driving device is used to drive the heavy vehicle to move on the track, and the heavy vehicle is provided with a column lifting mechanism for clamping the jacking support; the first and second trolleys are moved to designated positions under the drive of the driving device, the lifting mechanism fixes the first trolley, and the column lifting mechanism is flipped to install the jacking support at the designated position.

[0010] Preferably, the transport vehicle also includes a second trolley, which is provided with a jacking mechanism for fixation. The second trolley is arranged side by side with the first trolley, one end of the first drive device is connected to the end of the track, and the other end is connected to the second trolley, and the second trolley is provided with a mixer and a grouting pump.

[0011] Preferably, the jacking mechanism is a hydraulic jacking mechanism, which includes a hydraulic rod, a hydraulic cylinder and a pressure rod. Pressing the pressure rod causes the hydraulic rod to extend from the hydraulic cylinder and press against the top of the inclined tunnel.

[0012] Preferably, the first driving device includes a winch A, a winch B and a wire rope, the winch A and the winch B are arranged at the upper end of the track, the winch A is connected to the front end of the first trolley through a wire rope, and the winch B is connected to the front end of the second trolley through a wire rope.

[0013] Preferably, the second driving device includes a winch C, a pulley and a steel wire rope, the winch C and the pulley are arranged on the inclined plate of the first trolley, and the winch C is located in front of the pulley, a through hole is opened on the inclined plate, and the through hole is located behind the pulley, one end of the steel wire rope is connected to the winch C, and the other end is connected to the front end of the heavy vehicle through the pulley and the through hole.

[0014] Preferably, it also includes a lifting mechanism, which includes a winch D, a winch E and a wire rope. The winch D is installed on the first trolley, and the winch E is installed on the second trolley. The winch D and the winch E are connected to the column lifting mechanism through a wire rope, and the column lifting mechanism is rotatably connected to the heavy vehicle through a pin shaft.

[0015] Preferably, each of the column lifting mechanisms includes at least two groups of clamping units, and the clamping units include a column support plate and a column splint, the column support plate is located on the lower side of the column splint, the column support plate and the column splint are both arc-shaped, and the openings of the column support plate and the column splint are opposite to each other.

[0016] Preferably, the column lifting mechanism is installed on the heavy vehicle through a worm gear mechanism, and the worm gear mechanism includes a rotating steel plate, a bearing seat, a first worm and a first worm wheel. The column lifting mechanism is rotatably connected to the rotating steel plate through a pin shaft, the first worm wheel is fixed to the bottom of the rotating steel plate and is rotatably connected to the heavy vehicle, the first worm is engaged with the first worm wheel, and the first worm is installed on the heavy vehicle through the bearing seat.

[0017] Preferably, a ball screw mechanism is provided at the bottom of the worm gear mechanism, and the ball screw mechanism includes a sliding platform and a transmission unit. The worm gear mechanism is provided on the sliding platform, and the sliding platform is slidingly connected to the heavy vehicle base, and the transmission unit drives the sliding platform to move along the heavy vehicle base.

[0018] An embodiment of the present invention further provides a method for installing a jacking support for an inclined tunnel, which is installed using the above-mentioned jacking support installation machine for the inclined tunnel, comprising:

[0019] Positioning: The installation machine moves to the designated position under traction;

[0020] Fix the carrier: After determining the operating position of the installation machine, press the pressure rod to make the hydraulic rod push against the top of the tunnel to fix the carrier;

[0021] Installation of the jacking bracket: After the carrier is fixed, the column lifting mechanism is flipped through the lifting mechanism. At the same time, the position of the jacking bracket is controlled by the worm gear mechanism and the ball screw mechanism. After the jacking bracket is installed to the specified position, the column clamp is released;

[0022] Repeat the above steps to install the remaining jacking brackets.

[0023] One or more technical solutions provided in the embodiments of the present invention have at least the following technical effects or advantages:

[0024] 1. When in use, the inclined tunnel support installation machine of the present invention lays a track on the bottom surface of the inclined tunnel, utilizes the first driving device to pull the first trolley, and at the same time the first trolley pulls the heavy vehicle to move on the track. After moving to the designated position, the first trolley is fixed by the jacking mechanism on the first trolley, and then the jacking support is installed by the column lifting mechanism on the heavy vehicle, which solves the problem of inclined tunnel support installation, thereby further reducing labor intensity, improving support installation efficiency, ensuring the personal safety of workers, and reducing labor costs.

[0025] 2. The inclined tunnel jacking support installation machine mentioned in the present invention has a simple structure, easy operation, stable performance, and accelerates the installation speed of the support. In addition, the materials are easy to obtain and the production cost is low. The installation method is simple and easy to implement.

[0026] Additional advantages of the present invention will be given in the description which follows, and in part will be obvious from the description which follows, or may be learned through practice of the present invention.

[0027] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0029] Figure 1 Schematic diagram of an inclined tunnel jacking support installation machine provided by an embodiment of the present invention;

[0030] Figure 2 Schematic diagram of a trolley a of an inclined tunnel jacking support installation machine provided by an embodiment of the present invention;

[0031] Figure 3 Schematic diagram of trolley b of the inclined tunnel jacking support installation machine provided by an embodiment of the present invention;

[0032] Figure 4 Schematic diagram of a heavy vehicle for installing a jacking support in an inclined tunnel provided by an embodiment of the present invention;

[0033] Figure 5 is a schematic diagram of a worm gear mechanism and a ball screw mechanism according to an embodiment of the present invention;

[0034] In the figure: 1. Winch A; 2. Winch B; 3. Track; 4. Wire rope; 5. Lifting bracket; 6. Buckle; 7. Winch C; 8. Wheel; 9. Mixer; 10. Heavy vehicle; 11. Travel wheel; 12. Pulley; 13. Winch D; 14. Hydraulic rod; 15. Hydraulic cylinder; 16. Pressure rod; 17. Winch E; 18. Grouting pump; 19. Platform; 20. Winch F; 21. Winch G; 22. Winch H; 23. Column support plate; 24. Column clamping plate; 25. Pin; 26. Rotating steel plate; 27. Hand crank; 28. Bearing seat; 29. ​​First worm; 30. First worm gear; 31. Second worm; 32. Second worm gear; 33. Lead screw; 34. Nut; 35. Nut seat; 36. Sliding block; 37. Sliding platform

[0035] In order to show the positions of various parts, the distances or sizes between them are exaggerated. The schematic diagram is for reference only. DETAILED DESCRIPTION

[0036] It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0037] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless otherwise expressly specified in the present invention, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0038] Explanation of terms: The terms "installed", "connected", "connected", "fixed", etc. in the present invention should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral body; it can be a mechanical connection, a direct connection, or an indirect connection through an intermediate medium, it can be an internal connection between two elements, or an interaction relationship between two elements. For ordinary technicians in this field, the specific meaning of the terms in the present invention can be understood according to the specific circumstances. The terms "first", "second", etc. are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second", etc. may explicitly or implicitly include one or more of such features.

[0039] Due to the problems mentioned in the background technology, a mechanical device that is suitable for inclined tunnels and can realize the installation of jacking supports is very necessary, and this device should also have the characteristics of being easy to move and transport.

[0040] like Figure 1-Figure 5 As shown, in one embodiment of the present invention, a jacking support installation machine for an inclined tunnel is proposed, comprising: a track 3, a carrier and a driving device; the track 3 is used to be laid in the inclined tunnel, the carrier comprises a first trolley (i.e., trolley a) and a heavy vehicle 10, and the heavy vehicle 10 is installed on the track 3; the driving device comprises a first driving device and a second driving device, one end of the first driving device is connected to the end of the track 3, and the other end is connected to the first trolley, and the first trolley is provided with a jacking mechanism for fixing; one end of the second driving device is connected to the first trolley, and the other end is connected to the heavy vehicle 10, and the heavy vehicle 10 is provided with a column lifting mechanism for clamping the jacking support 5.

[0041] When in use, the inclined tunnel support installation machine of the present invention lays a track on the bottom surface of the inclined tunnel, utilizes a first driving device to pull a first trolley, and simultaneously the first trolley pulls a heavy vehicle to move on the track. After moving to a designated position, the first trolley is fixed by a lifting mechanism on the first trolley (that is, the second trolley is fixed at the same time), and then the lifting support is installed by a column lifting mechanism on the heavy vehicle, thereby solving the problem of inclined tunnel support installation, thereby further reducing labor intensity, improving support installation efficiency, ensuring the personal safety of workers, and reducing labor costs.

[0042] The carrier vehicle also includes a second trolley (i.e., trolley b), which is arranged side by side with the first trolley. One end of the first driving device is connected to the end of the track 3, and the other end is connected to the second trolley. The second trolley is provided with a mixer 9 and a grouting pump 18. The bracket grouting is immediately followed by the bracket erection, so that the bracket can be crimped to achieve the synchronization of the bracket erection and grouting. The mixer 9 is closed after the feeding is completed and stirred for 8-10 minutes. After the slurry is qualified, the grouting pump 18 is turned on for grouting. The grouting pump 18 is connected to the grouting port of the jacking bracket through the grouting pipe. During the grouting process, the bracket is knocked and vibrated to ensure the density of the grouting. After the bracket grouting and jacking are completed, the grouting pump 18 is turned off to end the grouting.

[0043] The first trolley and the second trolley are provided with a hydraulic jacking mechanism, which includes a hydraulic rod 14, a hydraulic cylinder 15 and a pressure rod 16. By pressing the pressure rod 16, the hydraulic oil is pressed into the rodless cavity of the hydraulic cylinder 15, thereby pushing the hydraulic rod 14 out of the hydraulic cylinder 15 and pressing it on the top of the inclined tunnel, thereby realizing relative support between the trolley and the tunnel top. During installation operations, the hydraulic jacking mechanism plays a fixing role.

[0044] The first driving device includes a winch A1, a winch B2 and a wire rope 4. The winch A1 and the winch B2 are arranged at the upper end of the track 3. The winch A1 is connected to the front end of the first trolley through the wire rope 4, and the winch B2 is connected to the front end of the second trolley through the wire rope 4. Figure 1 As shown, one end of the wire rope 4 of the first driving device is fixed on the winch A1 and the winch B2 respectively, and the other end is fixed on the trolley a and the trolley b respectively. The winch A1 and the winch B2 pull the trolley a and the trolley b upward through the wire rope 4.

[0045] like Figure 1 、 Figure 2As shown, the second driving device includes a winch C7, a pulley 12 and a wire rope 4. The winch C7 and the pulley 12 are arranged on the inclined plate of the first trolley, and the winch C7 is located in front of the pulley 12. A through hole is opened on the inclined plate, and the through hole is located behind the pulley 12. One end of the wire rope 4 is connected to the winch C7, and the other end is connected to the front end of the heavy vehicle 10 through the pulley 12 and the through hole.

[0046] like Figure 1 As shown, one end of the wire rope 4 of the second driving device is fixed on the winch C7, and the other end passes through the hole on the trolley a through the pulley 12 and is connected to the heavy vehicle 10. When the trolley a moves, the heavy vehicle is pulled upward by the second driving device.

[0047] Furthermore, the installation machine of this embodiment rotates the column lifting mechanism through a lifting mechanism, and the lifting mechanism includes a winch D13, a winch E17 and a wire rope. The winch D13 is installed on the first trolley, and the winch E17 is installed on the second trolley. The winch D13 and the winch E17 are connected to the column lifting mechanism through a wire rope 4. The column lifting mechanism is rotatably connected to the heavy vehicle 10 (i.e., the worm gear mechanism below) through a pin shaft 25. Under the action of the lifting mechanism, the flipping movement of the jacking bracket is realized.

[0048] Specifically, such as Figure 1 、 Figure 2 、 Figure 3 As shown, the above-mentioned lifting mechanism includes a wire rope, a winch D13, a winch E17, a winch F20, a winch G21 and a winch H22. The winch D13 and the winch E17 are respectively connected to the winch F20 and the winch H22 through wire ropes. When the jacking brackets on both sides are installed, the winch G21 can be connected to the winch D13 or the winch E17 through the wire rope 4 to install the jacking bracket in the middle position.

[0049] like Figure 4 As shown, each column lifting mechanism includes at least two sets of clamping units, each of which includes a column support plate 23 and a column clamping plate 24. The column support plate 23 is located below the column clamping plate 24. Both the column support plate 23 and the column clamping plate 24 are arc-shaped, and the openings of the column support plate 23 and the column clamping plate 24 are opposite to each other. Figure 1 As shown, a buckle 6 is installed on the jacking bracket 5. When working, the jacking bracket is placed on the column support plate 23 and then tightened with the column clamping plate 24. The buckle 6 is located between the two clamping units to prevent the axial movement of the jacking bracket. Figure 4 As shown, in this embodiment, three lifting mechanisms are arranged side by side, and each lifting mechanism has two clamping units.

[0050] like Figure 4 、 Figure 5 As shown, the heavy vehicle includes a column lifting mechanism, a worm gear mechanism, and a ball screw mechanism. The column lifting mechanism can rotate and translate under the action of the worm gear mechanism and the ball screw mechanism, so that the jacking bracket can reach the specified position more accurately.

[0051] like Figure 5 As shown, the column lifting mechanism is installed on the heavy vehicle 10 (i.e., a ball screw mechanism) through a worm gear mechanism, and the worm gear mechanism includes a rotating steel plate 26, a bearing seat 28, a first worm 29 and a first worm wheel 30. The column lifting mechanism is rotatably connected to the rotating steel plate 26 through a pin shaft 25. The first worm wheel 30 is fixed to the bottom of the rotating steel plate 26 and is rotatably connected to the heavy vehicle 10 (i.e., a ball screw mechanism). The first worm 29 is engaged with the first worm wheel 30. The first worm 29 is installed on the sliding platform 37 through the bearing seat 28. The rotational movement of the jacking bracket is realized by driving the hand crank 27.

[0052] like Figure 5 As shown, a ball screw mechanism is provided at the bottom of the worm gear mechanism, and the ball screw mechanism includes a sliding platform and a transmission unit. The worm gear mechanism is provided on the sliding platform, and the sliding platform is slidingly connected to the base of the heavy vehicle 10. The transmission unit drives the sliding platform to move along the base of the heavy vehicle 10.

[0053] The transmission unit includes a second worm 31, a second worm wheel 32, a screw 33, a nut 34, a nut seat 35, and a slider 36. The slider 36 is fixed on the heavy vehicle base, and the nut seat 35 is fixed on the bottom of the sliding platform. Driven by the second worm 31 and the second worm wheel 32, the ball screw starts to work, causing the sliding platform 37 to translate and thereby realize the translational movement of the jacking bracket.

[0054] In this embodiment, wheels 8 are installed at the bottom of trolleys a and b, and running wheels 11 are installed at the bottom of heavy vehicle 10. Running wheels 11 move along track 3. The running wheels are prefabricated with different wheel gauges according to different track gauges. Before the installation machine is operational, running wheels of different specifications can be replaced according to the track gauge, greatly expanding the application range of the installation machine. Platforms 19 are installed on trolleys a, b, and heavy vehicle to facilitate the movement of personnel with the transport vehicle.

[0055] The following uses the installation of steel tube concrete support as an example to illustrate the use of this device:

[0056] Step 1: Positioning. The installation machine moves to the designated position under traction.

[0057] Step 2: Secure the carrier. After determining the operating position of the installation machine, press the pressure rod to push the hydraulic rod to the top of the tunnel to secure the carrier.

[0058] Step 3: Bracket Installation. After the carrier is secured, the lifting mechanism flips the column support mechanism. Simultaneously, the worm gear and ball screw mechanisms control the bracket position. Once the bracket is in the designated position, release the column clamp. This completes the bracket installation on one side. Repeat the above steps for the remaining brackets.

[0059] Although the above describes the specific embodiments of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without any creative work are still within the scope of protection of the present invention.

Claims

1. A jacking support installation machine for an inclined tunnel, characterized in that: include: Tracks, carriers and drive units; The track is laid in an inclined lane, and the transport vehicle includes a first trolley and a heavy vehicle, and the heavy vehicle is installed on the track; The driving device includes a first driving device and a second driving device. The first driving device drives the first trolley to move in the inclined tunnel. The first trolley is provided with a jacking mechanism for fixing the first trolley. The second driving device is used to drive the heavy vehicle to move on the track. The heavy vehicle is provided with a column lifting mechanism for clamping the jacking bracket. The pulling mechanism also includes a winch D, a winch E and a wire rope. The driving device drives the first trolley and the heavy vehicle to move to a designated position, the lifting mechanism fixes the first trolley, and the column lifting mechanism flips to install the lifting bracket at the designated position; The jacking mechanism is a hydraulic jacking mechanism, which includes a hydraulic rod, a hydraulic cylinder and a pressure rod; the column lifting mechanism is installed on the heavy vehicle through a worm gear mechanism; a ball screw mechanism is provided at the bottom of the worm gear mechanism; A method for installing an inclined roadway jacking support using an inclined roadway jacking support installation machine includes: Positioning: The installation machine moves to the designated position under traction; Fix the carrier: After determining the operating position of the installation machine, press the pressure rod to make the hydraulic rod push against the top of the tunnel to fix the carrier; Installation of the jacking bracket: After the carrier is fixed, the column lifting mechanism is flipped through the lifting mechanism. At the same time, the position of the jacking bracket is controlled by the worm gear mechanism and the ball screw mechanism. After the jacking bracket is installed to the specified position, the column clamp is released; Repeat the above steps to install the remaining jacking brackets.

2. The inclined tunnel jacking support installation machine according to claim 1, characterized in that: The carrier vehicle also includes a second trolley, which is provided with a jacking mechanism for fixing. The second trolley is arranged side by side with the first trolley. One end of the first drive device is connected to the end of the track and the other end is connected to the second trolley. The second trolley is provided with a mixer and a grouting pump.

3. The inclined tunnel jacking support installation machine according to claim 1, characterized in that: The pressure rod is pressed to make the hydraulic rod extend from the hydraulic cylinder and press against the top of the inclined roadway.

4. The inclined tunnel jacking support installation machine according to claim 2, characterized in that: The first driving device includes a winch A, a winch B and a wire rope. The winch A and the winch B are arranged at the upper end of the track. The winch A is connected to the front end of the first trolley through a wire rope, and the winch B is connected to the front end of the second trolley through a wire rope.

5. The inclined tunnel jacking support installation machine according to claim 1, characterized in that: The second driving device includes a winch C, a pulley and a steel wire rope. The winch C and the pulley are arranged on the inclined plate of the first trolley, and the winch C is located in front of the pulley. A through hole is opened on the inclined plate, and the through hole is located behind the pulley. One end of the steel wire rope is connected to the winch C, and the other end is connected to the front end of the heavy vehicle through the pulley and the through hole.

6. The inclined tunnel jacking support installation machine according to claim 2, characterized in that: The winch D is installed on the first trolley, and the winch E is installed on the second trolley. The winch D and the winch E are connected to the column lifting mechanism through steel wire ropes, and the column lifting mechanism is rotatably connected to the heavy vehicle through a pin shaft.

7. The inclined tunnel jacking support installation machine according to claim 1, characterized in that: Each of the column lifting mechanisms includes at least two groups of clamping units, and the clamping units include a column support plate and a column splint. The column support plate is located on the lower side of the column splint. The column support plate and the column splint are both arc-shaped, and the openings of the column support plate and the column splint are opposite to each other.

8. The inclined tunnel jacking support installation machine according to claim 1, characterized in that: The worm gear mechanism includes a rotating steel plate, a bearing seat, a first worm and a first worm wheel. The column lifting mechanism is rotatably connected to the rotating steel plate through a pin shaft. The first worm wheel is fixed to the bottom of the rotating steel plate and is rotatably connected to the heavy vehicle. The first worm is engaged with the first worm wheel, and the first worm is installed on the heavy vehicle through the bearing seat.

9. The inclined tunnel jacking support installation machine according to claim 1, characterized in that: The ball screw mechanism includes a sliding platform and a transmission unit. The worm gear mechanism is arranged on the sliding platform. The sliding platform is slidably connected to the heavy vehicle base. The transmission unit drives the sliding platform to move along the heavy vehicle base.

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