High-strength civil air defense door convenient to open and close quickly and smoothly

Abstract

The invention relates to a high-strength civil air defense door convenient to open and close quickly and smoothly, and relates to the technical field of civil air defense doors. Comprising a doorsill assembly, base assemblies are symmetrically fixed to the two sides of the doorsill assembly, one end of a door spindle is rotationally installed in each base assembly, and the two door spindles are fixedly provided with a manned defense door body respectively; two movable thresholds are arranged in the threshold assembly, and the lifting motion of each movable threshold is controlled by the rotation linkage of the corresponding door shaft; a self-lubricating mechanism is arranged in the base assembly, and the self-lubricating mechanism drives lubricating oil to flow along with rotation of the door shaft. The door shaft is used for rotating the movable threshold to perform lifting motion in the threshold sliding groove, and the trafficability of the civil air defense door and the partition performance under the emergency condition are well compatible; and meanwhile, a self-lubricating structure is arranged, lubricating oil is pumped and conveyed into the upper cavity from the lower cavity through rotation of the door shaft when the civil air defense door is opened and closed, the positioning bearing and the bearing bearing are lubricated, and the rotation process of the civil air defense door is smoother and saves more labor.

Description

Technical Field

[0001] The present invention relates to the technical field of civil air defense doors, and in particular to a high-strength civil air defense door which is easy to open and close quickly and smoothly. Background Art

[0002] As an important part of civil defense projects, civil defense doors bear the important responsibility of protecting the lives and property of personnel in emergency situations. However, traditional civil defense doors often have some defects in design.

[0003] For example, civil air defense doors in underground garages are often set up without thresholds because vehicles need to pass through them. Although this ensures the passability of vehicles, underground garages often also bear the function of emergency shelters, so their ability to isolate some harmful substances also needs to be considered. The existing technology lacks such civil air defense doors that automatically raise and lower the thresholds as the civil air defense doors open and close, which can ensure both the passability of vehicles and the effectiveness of emergency partitions. At the same time, the existing civil air defense doors are easy to get stuck due to oxidation and rust of the transmission parts when they are in the open or closed state for a period of time, making them difficult to open or close quickly, which brings safety hazards and inconveniences in use. They require manual regular lubrication and maintenance, which is time-consuming and labor-intensive. To this end, we provide a high-strength civil air defense door that is easy to open and close quickly and smoothly. Summary of the invention

[0004] The purpose of the present invention is to provide a high-strength civil defense door that is easy to open and close quickly and smoothly.

[0005] The technical problems solved by the present invention are:

[0006] (1) The existing underground garage air defense door lacks the function of automatically raising and lowering the threshold according to the opening and closing process, and thus cannot provide both passing performance and partitioning performance;

[0007] (2) In the prior art, the moving parts related to the door shaft need to be manually operated and lubricated regularly, otherwise they will rust and make it difficult for the civil air defense door to quickly switch the open and closed states.

[0008] The present invention can be implemented through the following technical scheme: a high-strength civil air defense door that is easy to open and close quickly and smoothly, comprising a threshold assembly fixed to the ground, base assemblies symmetrically fixed on both sides of the threshold assembly, one end of a door shaft rotatably mounted in each base assembly, the other end of the door shaft being constrained to a vertical state by a fixed base fixed to a wall, the door shaft and the fixed base being rotatably arranged, and the two door shafts being respectively fixedly arranged with a civil air defense door body;

[0009] The threshold assembly is provided with two movable thresholds arranged side by side and capable of moving up and down, and the lifting and lowering movement of each movable threshold is controlled by the rotation linkage of the corresponding door shaft; when the door shaft drives the civil air defense door body to close, the movable threshold rises, and when the door shaft drives the civil air defense door body to open, the movable threshold falls;

[0010] A self-lubricating mechanism for lubricating the rotating bearing structure of the door shaft is arranged in the base assembly, and the self-lubricating mechanism drives the lubricating oil to flow as the door shaft rotates.

[0011] A further technical improvement of the present invention is that the threshold assembly includes a threshold fixing seat fixed to the ground and with the top flush with the ground, and the movable threshold slides up and down in the slide groove of the threshold fixing seat; a rotating shaft is rotatably installed in the bottom inner cavity of the threshold fixing seat, and a plurality of cam mechanisms with the same rotation are arranged on the rotating shaft. After the rotating shaft rotates, the cam mechanism is driven to move, so that the movable threshold moves upward or downward.

[0012] A further technical improvement of the present invention is that the cam mechanism includes a rotating disk coaxially fixed on the outer periphery of the rotating shaft, arc grooves are symmetrically provided on both side walls of the rotating disk, rollers are rollingly arranged in the arc grooves, a connecting rod is installed on one side of each roller for relative rotation through a pin shaft, and the connecting rod passes through the bottom inner cavity and is fixed to the bottom of the movable threshold.

[0013] A further technical improvement of the present invention is that: a connecting protrusion is provided on one adjacent side of two movable thresholds, the connecting protrusions on the two movable thresholds are arranged alternately and intermittently, a groove is formed between two adjacent connecting protrusions on the same movable threshold, and the shape of the groove just matches the shape of the connecting protrusion.

[0014] A further technical improvement of the present invention is that dust accumulation grooves for receiving dust or foreign matter dropped from the ground are provided on both sides of the slide groove where the movable door sill slides at the top of the door sill fixing seat.

[0015] A further technical improvement of the present invention is that: the base assembly includes a threshold base, an upper chamber and a lower chamber are provided in the threshold base, the door shaft passes through the upper chamber and extends to the lower chamber, a section of the door shaft located in the upper chamber is provided with a shoulder, a load-bearing bearing is coaxially arranged at the bottom of the shoulder for pressure bearing and axial limiting, a coaxial sleeve on the outer periphery of the shoulder is provided with a positioning bearing for radial positioning of the door shaft, a bevel gear 1 is coaxially fixed to the end of the door shaft located in the lower chamber, one end of the rotating shaft passes through the threshold base and extends into the lower chamber and a bevel gear 2 is coaxially fixed to the end, and bevel gear 1 is meshed with bevel gear 2 for transmission.

[0016] A further technical improvement of the present invention is that the self-lubricating mechanism includes a rotating cam coaxially fixed on the outer periphery of the door shaft located in the lower chamber and three extrusion wheels are evenly rotated on its outer periphery, and a hose is fixed on the side wall of the lower chamber at the same height as the rotating cam, one end of the hose is connected to the lubricating oil arranged in the lower chamber, and the other end is connected to the side wall of the upper chamber higher than the position of the positioning bearing, and the rotating cam is used to drive the extrusion wheel to extrude the hose to pump the lubricating oil to the upper chamber.

[0017] A further technical improvement of the present invention is that an oil supply channel is horizontally opened at the bottom position of the lower chamber to connect to the outside, and a plug is arranged in the oil supply channel, an oil suction pipe is vertically opened in the side wall of the lower chamber to connect the oil supply channel and the hose, an oil delivery interlayer is arranged on the side wall position of the upper chamber higher than the positioning bearing, and the other end of the hose is connected to the oil delivery interlayer through the oil delivery channel opened in the side wall of the threshold base.

[0018] A further technical improvement of the present invention is that the oil transfer interlayer is inclined downward at a certain angle in the radial direction toward the center of the chamber.

[0019] A further technical improvement of the present invention is that one or two self-lubricating mechanisms are provided. When one is provided, a lubrication cycle is completed each time the civil air defense door is opened and closed; when two are provided, a lubrication cycle is completed each time the civil air defense door is opened and closed.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The present invention utilizes the power of the rotation of the door shaft to drive the movable threshold to move up and down in the threshold slide groove. When the civil air defense door is closed, the movable threshold rises, and when the civil air defense door is opened, the movable threshold is hidden, thereby ensuring the passability of the civil air defense door and the partition performance in emergency situations. This mechanical linkage transmission is more reliable than the electric drive method. Under emergency conditions, more driving sources (such as electricity, etc.) will inevitably fail. The reliable mechanical transmission can ensure the lifting stability of the movable threshold during the opening and closing process of the civil air defense door, which is more reliable and safe.

[0022] 2. The present invention sets a self-lubricating structure and utilizes the rotation of the door shaft when the civil air defense door is opened and closed to pump the lubricating oil from the lower chamber to the upper chamber to lubricate the positioning bearing and the load-bearing bearing, making the rotation process of the civil air defense door smoother and more labor-saving. It is only necessary to check whether there is sufficient lubricating oil in the lower chamber (a liquid level sensor can be set), and there is no need for manual operations such as regular oiling and lubrication of the door shaft, which saves time and effort. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to facilitate understanding by those skilled in the art, the present invention is further described below with reference to the accompanying drawings.

[0024] Figure 1 It is a schematic diagram of the overall external structure of the present invention;

[0025] Figure 2 It is a schematic diagram of the three-dimensional connection structure of the door sill assembly of the present invention;

[0026] Figure 3 For the present invention Figure 2 A partial enlarged view of the middle A;

[0027] Figure 4 It is a schematic diagram of the connection structure of the rotating disk, the roller and the connecting rod of the present invention;

[0028] Figure 5 It is a schematic diagram of the connection state between the base assembly and the threshold assembly of the present invention;

[0029] Figure 6 It is a schematic diagram of the base assembly and door shaft installation structure of the present invention;

[0030] Figure 7 It is a cross-sectional schematic diagram of the matching state of the rotating cam, the hose and the door sill base of the present invention.

[0031] In the figure: 1. threshold assembly; 2. base assembly; 3. door shaft; 4. fixed base; 5. civil air defense door body; 101. threshold fixing seat; 102. threshold slide groove; 103. dust accumulation groove; 104. movable threshold; 105. rotating shaft; 106. rotating disk; 107. connecting rod; 201. threshold base; 202. cover plate; 203. positioning bearing; 204. load-bearing bearing; 205. rotating cam; 207. extrusion wheel; 208. hose; 209. oil suction channel; 210. oil delivery channel; 212. oil replenishment channel; 213. plug; 214. lubricating oil; 215. oil delivery interlayer; 216. bevel gear one; 217. bevel gear two; 501. upper connecting support; 502. lower connecting support; 1041. connecting protrusion; 1061. arc groove; 1071. roller. DETAILED DESCRIPTION

[0032] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0033] See also Figure 1-7 As shown, a high-strength civil air defense door that is easy to open and close quickly and smoothly includes a threshold assembly 1 and base assemblies 2 symmetrically fixed to the ground on both sides thereof, one end of a door shaft 3 is rotatably mounted in each base assembly 2, and the top position of the door shaft 3 is rotatably connected to a fixed base 4, which is fixed to the wall;

[0034] A human air defense door body 5 is fixedly arranged on one side of the two door shafts 3, and an upper connecting support 501 and a lower connecting support 502 are fixed on one side of the human air defense door body 5, and the human air defense door body 5 is fixed to the corresponding door shaft 3 through the upper and lower connecting supports;

[0035] When the two air defense door bodies 5 are closed, the movable parts of the corresponding threshold assemblies 1 rise synchronously and cooperate with the bottom of the air defense door bodies 5 to remain closed. When the two air defense door bodies 5 are opened, the movable parts of the corresponding threshold assemblies 1 descend synchronously to ensure the flatness of the ground and avoid obstruction to the passage of vehicles or pedestrians.

[0036] Specifically, the threshold assembly 1 includes a threshold fixing seat 101 fixed to the ground, the top plane of the threshold fixing seat 101 is flush with the ground, a threshold slide groove 102 is provided at the top middle position of the threshold fixing seat 101, two movable thresholds 104 are provided in the extension direction of the threshold slide groove 102, and the two movable thresholds 104 slide up and down in the threshold slide groove 102; a connecting protrusion 1041 is provided on the adjacent side of the two movable thresholds 104, and the connecting protrusions 1041 on the two movable thresholds 104 are alternately intermittently arranged, and a groove is formed between two adjacent connecting protrusions 1041 on the same movable threshold 104, and the shape of the groove just matches the shape of the connecting protrusion 1041, thereby forming a Figure 3 The connection status shown;

[0037] A transmission cavity is provided at the bottom of the threshold fixing seat 101, and a rotating shaft 105 is rotatably installed in the transmission cavity. A plurality of rotating disks 106 are evenly and coaxially fixed on the outer periphery of the rotating shaft 105. Arc grooves 1061 arranged in a gradually opening shape are symmetrically opened on both side walls of the rotating disk 106. A roller 1071 is rotatably arranged in each arc groove 1061. One side pair of the rollers 1071 is relatively rotatably arranged with the corresponding connecting rods 107 through the pin shaft. The tops of the two connecting rods 107 pass through the transmission cavity and are fixed to the bottom of the movable threshold 104.

[0038] Dust collecting grooves 103 are symmetrically arranged on both sides of the threshold slide groove 102 to receive dust or foreign matter dropped from the ground, thereby ensuring the normal operation of the threshold assembly 1 .

[0039] One end of the rotating shaft 105 close to the base assembly 2 passes through the threshold assembly 1 and extends into the threshold base 201 of the base assembly 2. A cover plate 202 is fixedly installed on the top of the threshold base 201 by bolts. The interior of the threshold base 201 is divided into an upper chamber and a lower chamber. The door shaft 3 passes through the cover plate 202 and extends through the upper chamber into the lower chamber. A section of the door shaft 3 located in the upper chamber is provided with a shoulder. A load-bearing bearing 204 is coaxially arranged on the outer periphery of the door shaft 3 at the bottom of the shoulder, so as to bear the gravity of the door shaft 3 and the civil air defense door body 5. A positioning bearing 203 is coaxially fixed on the outer periphery of the shoulder to radially fix the door shaft 3.

[0040] A rotating cam 205 is coaxially fixedly installed on the outer periphery of one end of the door shaft 3 extending to the lower chamber, and three squeezing wheels 207 are rotatably installed at equal angles on the outer periphery of the rotating cam 205. A semi-annular groove is opened on the door sill base 201 at the same height as the rotating cam 205, and a hose 208 is fixed in the installation annular groove. The squeezing wheel 207 squeezes the hose 208 at the location of the hose 208, so that the liquid in the hose 208 is pumped under the action of the squeezing wheel 207.

[0041] An oil replenishment channel 212 is horizontally opened at the bottom of the threshold base 201, and the oil replenishment channel 212 is connected to the lower chamber. A plug 213 is installed at the end of the oil replenishment channel 212 to isolate it from the external environment. An oil suction channel 209 is vertically opened on one side of the inner wall of the threshold base 201. The bottom of the oil suction channel 209 is connected to the oil replenishment channel 212, and the top of the oil suction channel 209 is connected to the semi-annular groove; an oil delivery channel 210 is opened on the other side of the inner wall of the threshold base 201, and an oil delivery interlayer 215 is opened on the side wall of the upper chamber above the top plane position of the positioning bearing 203. The bottom of the oil delivery channel 210 is connected to the semi-annular groove, and the top is connected to the oil delivery interlayer 215;

[0042] More specifically, a joint is sealed in one end of the semi-annular groove where the oil suction channel 209 communicates with the oil delivery channel 210, and both ends of the hose 208 are sealed and connected to the two joints, thereby forming a flow channel from the oil replenishment channel 212 to the oil delivery interlayer 215; the oil delivery interlayer 215 is tilted downward at a certain angle in the radial direction toward the center of the chamber, so that the liquid flowing out of the oil delivery interlayer 215 can flow into the upper chamber;

[0043] A certain depth of lubricating oil 214 is provided in the lower chamber, and the lubricating oil 214 is replenished into the lower chamber through the oil replenishing channel 212 .

[0044] The rotating shaft 105 extends to one end of the lower chamber and is coaxially fixed with a bevel gear 217. The door shaft 3 extends to one end of the lower chamber and is coaxially fixed with a bevel gear 1 216. The bevel gear 1 216 and the bevel gear 2 217 are meshed for transmission, and the lower half of the bevel gear 2 217 is immersed in the lubricating oil 214, providing lubrication for the transmission of the gear pair.

[0045] When the present invention is in use, during the process of the civil defense door body 5 rotating and closing, the door shaft 3 is driven to rotate synchronously, and the transmission action of the bevel gear pair is used to drive the rotating shaft 105 to rotate. The rotating disk 10 fixed on the outer periphery of the rotating shaft 105 causes the roller 1071 to roll in the arc groove 1061, so that the connecting rod 107 pushes the movable threshold 104 upward. After the movable threshold 104 rises, it is higher than the ground. When the civil defense door body 5 is completely closed, the movable threshold 104 rises to the highest position and fits tightly with the corresponding position of the civil defense door body 5. On the one hand, it limits the angle of the civil defense door body 5, and on the other hand, it is sealed and fitted with the civil defense door body 5. The contact part between the civil defense door body 5 and the movable threshold 104 is attached and fixed. There is a rubber anti-collision strip; during the rotation of the door shaft 3, a rotating cam 205 is coaxially fixed on its outer periphery, and the extrusion wheel 207 rotatably arranged on the rotating cam 205 squeezes the hose 208, thereby pumping and transporting the fluid in the hose 208, and transporting the lubricating oil 214 from the oil replenishing channel 212, the oil suction channel 209, and the hose 208 to the oil delivery channel 210 and finally flows out from the oil delivery interlayer 215 and drips on the positioning bearing 203, and then the lubricating oil 214 flows downward to lubricate the load-bearing bearing 204, and finally flows back into the lower chamber, completing a lubrication cycle, thereby maintaining the entire rotating component, making the civil air defense door smoother and more labor-saving in the subsequent opening and closing process;

[0046] During the process of the civil air defense door body 5 rotating to open, similarly, the door shaft 3 rotates to drive the rotating shaft 105 to rotate, thereby driving the movable threshold 104 to drop back into the threshold slide groove 102. When the civil air defense door body 5 is completely opened, the top of the movable threshold 104 is lower than the ground plane; however, we noticed that during the opening process, the lubricating oil 214 cannot be pumped into the transport channel of the lubricating oil 214, and only air can be pumped in the reverse direction;

[0047] In order to be able to complete a lubrication cycle during the opening process, in other embodiments, a rotating cam 205 is installed at one end of the door shaft 3 extending to the lower chamber, and at the same time, a set of the same flow channel structure regarding the hose 208, the oil suction channel 209, and the oil delivery channel 210 is arranged in the side wall of the lower chamber and connected to the oil delivery interlayer 215, so that during the process of the door shaft 3 rotating to open, the lubricating oil 214 can also be pumped to the oil delivery interlayer 215 and flow to complete a lubrication cycle.

[0048] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A high-strength civil air defense door that is easy to open and close quickly and smoothly, characterized in that: The invention comprises a threshold assembly (1) fixed to the ground, base assemblies (2) being symmetrically fixed on both sides of the threshold assembly (1), one end of a door shaft (3) being rotatably mounted in each base assembly (2), the other end of the door shaft (3) being constrained to a vertical state by a fixed base (4) fixed to a wall, the door shaft (3) and the fixed base (4) being rotatably arranged, and two door shafts (3) being respectively fixedly arranged with a human air defense door body (5); The threshold assembly (1) is provided with two movable thresholds (104) arranged side by side and capable of moving up and down, and the lifting and lowering movement of each movable threshold (104) is controlled by the rotation linkage of the corresponding door shaft (3); when the door shaft (3) drives the civil air defense door body (5) to close, the movable threshold (104) rises, and when the door shaft (3) drives the civil air defense door body (5) to open, the movable threshold (104) falls; The base assembly (2) is provided with a self-lubricating mechanism for lubricating the rotating bearing structure of the door shaft (3), and the self-lubricating mechanism drives the lubricating oil (214) to flow as the door shaft (3) rotates.

2. A high-strength civil air defense door that is easy to open and close quickly and smoothly according to claim 1, characterized in that: The threshold assembly (1) comprises a threshold fixing seat (101) fixed to the ground and with the top thereof flush with the ground, and a movable threshold (104) slidingly cooperates with the sliding groove of the threshold fixing seat (101) in an up-and-down manner; a rotating shaft (105) is rotatably mounted in the bottom inner cavity of the threshold fixing seat (101), and a plurality of cam mechanisms of the same rotation are arranged on the rotating shaft (105); after the rotating shaft (105) rotates, the cam mechanisms are driven to move, so that the movable threshold (104) moves upward or downward.

3. A high-strength civil defense door that is easy to open and close quickly and smoothly according to claim 2, characterized in that: The cam mechanism comprises a rotating disk (106) coaxially fixed on the outer periphery of a rotating shaft (105), arc grooves (1061) are symmetrically provided on two side walls of the rotating disk (106), rollers (1071) are rotatably arranged in the arc grooves (1061), a connecting rod (107) is relatively rotatably mounted on one side of each roller (1071) via a pin, and the connecting rod (107) passes through the bottom inner cavity and is fixed to the bottom of the movable threshold (104).

4. A high-strength civil air defense door that is easy to open and close quickly and smoothly according to claim 1, characterized in that: A connecting protrusion is provided on one adjacent side of the two movable thresholds (104); the connecting protrusions (1041) on the two movable thresholds (104) are arranged alternately and intermittently; a groove is formed between two adjacent connecting protrusions (1041) on the same movable threshold (104); and the shape of the groove just matches the shape of the connecting protrusion (1041).

5. The high-strength civil defense door that is easy to open and close quickly and smoothly according to claim 1 is characterized in that: Dust accumulation grooves (103) for receiving dust or foreign matter dropped from the ground are provided on both sides of the slide groove where the movable threshold (104) at the top of the threshold fixing seat (101) slides.

6. The high-strength civil defense door that is easy to open and close quickly and smoothly according to claim 2 is characterized in that: The base assembly (2) comprises a threshold base (201), wherein an upper chamber and a lower chamber are provided in the threshold base (201), a door shaft (3) passes through the upper chamber and extends to the lower chamber, a section of the door shaft (3) located in the upper chamber is provided with a shoulder, a load-bearing bearing (204) is coaxially arranged at the bottom of the shoulder for bearing pressure and axial limiting, a positioning bearing (203) is coaxially sleeved on the outer periphery of the shoulder for radial positioning of the door shaft (3), a bevel gear 1 (216) is coaxially fixed to the end of the door shaft (3) located in the lower chamber, one end of the rotating shaft (105) passes through the threshold base (201) and extends into the lower chamber and a bevel gear 2 (217) is coaxially fixed to the end, and the bevel gear 1 (216) is meshed with the bevel gear 2 (217) for transmission.

7. A high-strength civil air defense door that is easy to open and close quickly and smoothly according to claim 6, characterized in that: The self-lubricating mechanism comprises a rotating cam (205) coaxially fixed to the outer periphery of the door shaft (3) located in the lower chamber, and three extrusion wheels (207) are evenly rotated on its outer periphery. A section of hose (208) is fixed on the side wall of the lower chamber at the same height as the rotating cam (205). One end of the hose (208) is connected to the lubricating oil (214) arranged in the lower chamber, and the other end is connected to the side wall of the upper chamber higher than the position of the positioning bearing (203). The rotating cam (205) drives the extrusion wheel (207) to squeeze the hose (208) to pump the lubricating oil (214) to the upper chamber.

8. The high-strength civil air defense door that is easy to open and close quickly and smoothly according to claim 7 is characterized in that: An oil replenishment channel (212) is horizontally opened at the bottom of the lower chamber to connect to the outside, and a plug (213) is arranged in the oil replenishment channel (212); an oil suction pipeline (209) is vertically opened in the side wall of the lower chamber to connect the oil replenishment channel (212) and the hose (208); an oil delivery interlayer (215) is arranged at a side wall position of the upper chamber higher than the positioning bearing (203); the other end of the hose (208) is connected to the oil delivery interlayer (215) through an oil delivery channel (210) opened in the side wall of the threshold base (201).

9. A high-strength civil air defense door that is easy to open and close quickly and smoothly according to claim 8, characterized in that: The oil transfer interlayer (215) is inclined downward at a certain angle in the radial direction toward the center of the chamber.

10. A high-strength civil air defense door that is easy to open and close quickly and smoothly according to claim 8, characterized in that: The self-lubricating mechanism is provided with one or two. When provided with one, a lubrication cycle is completed each time the civil air defense door is opened and closed; when provided with two, a lubrication cycle is completed each time the civil air defense door is opened and closed.

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