CA1083204A - Trailer brake system - Google Patents
Trailer brake systemInfo
- Publication number
- CA1083204A CA1083204A CA289,900A CA289900A CA1083204A CA 1083204 A CA1083204 A CA 1083204A CA 289900 A CA289900 A CA 289900A CA 1083204 A CA1083204 A CA 1083204A
- Authority
- CA
- Canada
- Prior art keywords
- brake system
- trailer
- fluid pressure
- fluid
- towing vehicle
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Landscapes
- Braking Systems And Boosters (AREA)
Abstract
TRAILER BRAKE SYSTEM
Abstract of the Disclosure A brake system for a towing vehicle and trailer is disclosed. An electromechanical transducer controller connected to the towing vehicle brake system develops an electrical signal which varies continuously and systematically in accordance with braking action pressure in the towing vehicle brake system. In a fluid trailer brake system, an electromechanical control receives this signal, and con-tinuously and systematically varies the fluid pressure in the trailer brake system accordingly. A vacuum or other fluid power booster can be included to assist in amplifying and applying this fluid brake pressure. Trailer braking action in caliper-type trailer disc brakes varies in accor-dance with this fluid pressure.
Abstract of the Disclosure A brake system for a towing vehicle and trailer is disclosed. An electromechanical transducer controller connected to the towing vehicle brake system develops an electrical signal which varies continuously and systematically in accordance with braking action pressure in the towing vehicle brake system. In a fluid trailer brake system, an electromechanical control receives this signal, and con-tinuously and systematically varies the fluid pressure in the trailer brake system accordingly. A vacuum or other fluid power booster can be included to assist in amplifying and applying this fluid brake pressure. Trailer braking action in caliper-type trailer disc brakes varies in accor-dance with this fluid pressure.
Description
l~B3ZO~
Backgroun f the Invention_ This invention relates generally to brake systems for towing vehicle and trailer combinations The manufacture, sale and use of towed recreational vehicles of the camping or mobile home variety has accelerated at a rapid rate. These trailers must of course be provided with effective brakes adapted for operation in conjunction with the towing vehicle brakes. Many presently offered towing vehicle-trailer braking systems provide high degrees of reliability and control.
The general object of the present invention is to pro-vide a braking system for a trailer which further improves braking control of a towed and towing vehicle combination.
Statement of the Invention The invention provides a brake system for a towing vehicle and trailer which includes a towing vehicle fluid brake system, an electro-mechanical transducer connected to the towing vehicle fluid brake system for developing an elec-trical signal which varies proportionately in accordance with fluid pressure experienced in the towing vehicle brake system, a trailer fluid brake system, and an electromechanical control electrically connected to the transducer for proportionately varying the fluid pressure and consequent braking action in the trailer,brake system in accordance with the variation in the electrical signal. The control includes a power booster having a diaphragm between two chambers defined within the power booster, a diaphragm interconnector interposed between the diaphragm and the trailer fluid brake system, valve means responsive to the electrical signal for altering pressure in one of the power booster chambers, relative to the other cham-
Backgroun f the Invention_ This invention relates generally to brake systems for towing vehicle and trailer combinations The manufacture, sale and use of towed recreational vehicles of the camping or mobile home variety has accelerated at a rapid rate. These trailers must of course be provided with effective brakes adapted for operation in conjunction with the towing vehicle brakes. Many presently offered towing vehicle-trailer braking systems provide high degrees of reliability and control.
The general object of the present invention is to pro-vide a braking system for a trailer which further improves braking control of a towed and towing vehicle combination.
Statement of the Invention The invention provides a brake system for a towing vehicle and trailer which includes a towing vehicle fluid brake system, an electro-mechanical transducer connected to the towing vehicle fluid brake system for developing an elec-trical signal which varies proportionately in accordance with fluid pressure experienced in the towing vehicle brake system, a trailer fluid brake system, and an electromechanical control electrically connected to the transducer for proportionately varying the fluid pressure and consequent braking action in the trailer,brake system in accordance with the variation in the electrical signal. The control includes a power booster having a diaphragm between two chambers defined within the power booster, a diaphragm interconnector interposed between the diaphragm and the trailer fluid brake system, valve means responsive to the electrical signal for altering pressure in one of the power booster chambers, relative to the other cham-
- 2 - ~
1083Z0~
ber, so as to move the diaphragm interconnector means and vary the fluid pressure in and resultant braking action of the trailer brake system in accordance with diaphragm movement, and a fluid pressure supply means for creating a given, nor-mally equalized absolute fluid pressure in the power booster chambers. The control further includes safety valve means for altering the fluid pressure in one power booster chamber rela-tive to the other chamber and thereby providing braking action in the trailer braking system in response to a fluid pressure failure in the fluid pressure supply means, and a selectively operable brake release valve connected to the other of the power booster chambers so as to admit a fluid into the other chamber so as to re-equalize the pressure on the diaphragm and release the trailer braking system from further braking action, Other objects and advantages of the invention will be-come apparent upon reading the following detailed description .. . . .
~083ZV~ -and upon reference to the drawings. Throughout the drawings, like reference numerals refer to like parts.
Brief Description of the Drawin~s FIGURE 1 is a schematic diagram showing a novel brake system embodying the present invention;
FIG. 2 is a schematic diagram similar to FIG. 1 showing a modified version of the novel brake system; and FIG. 3 is a schematic diagram of a trailer brake power unit, an associated trailer brake master cylinder, and related apparatus.
Detailed Description While the invention will be described in connection with preferred embodiments, it will be understood that it is not intended to limit the invention to these embodiments.
On the contrary, it is intended to cover all alternatives, modifications and equivalents included within the spirit and scope of the invention and as defined by the appended claims.
Turning first to FIGURE 1 there is shown, in sche-matic form, an embodiment of the present novel braking system in use with a towing vehicle 10 and towed trailer 11. In gen~ral, the towing vehicle 10 carries an engine 14 for pro-pelling the towing vehicle 10 and the trailer 11. A towing vehicle brake system 15 selectively energizes associated :1083'~0~ -brakes (not shown). Mounted within and upon the trailer 11 is a trailer fluid brake system 16, and a control 17 mounted in and upon the trailer 11 which energizes and controls the trailer fluid brake system 16.
More specifically, when a driver of the towing vehicle 10 desires to retard its progress, he depresses a brake pedal 20 in well known manner. If the brakes on the towing vehicle 10 are of the hydraulic variety, and are of the "power brake" type, a power booster 21 is energized and actuates a hydraulic brake master cylinder 22. Appropriate hydraulic pressure is directed to towing vehicle rear wheel brakes through a hydraulic line 23, and to front wheel brakes through another line 24. Brake warning lights and other de-vices can be actuated through an appropriate switch 25.
An electromechanical transducer control 30 mounted on the towing vehicle 10 is energized by increased hydraulic pressure through an interconnector line 31. To provide a smooth infinitely controllable braking action to the trailer.
11 in accordance with the invention, this controller 30 modulates the towing vehicle hydraulic brake system brake pressure, and provides a correspondingly modulated electrical signal which varies systematically in accordance with fluid pressure experienced in the towing vehicle brake system inter-connector line 31. A manual override switch 32 can be included if desired to operate the trailer braking system 16 directly 108320~ .
Erom the towing vehicle 10. Appropriate electrical lines 33 and 34 connect the controller 30 to the towing vehicle elec-trical system battery or engine-driven generator, and to the system electrical ground, respectively. The electrical signal is transmitted by the controller 30 along appropriate wiring 36 through a quick-disconnect plug 37 and trailer wiring 38 to the trailer brake controller 17 mounted upon the trailer 11.
To maintain a common electrical ground, a wire 39 electrically interconnects appropriate grounding members of the trailer 11 and towing vehicle 10 through a ground wire interconnect plug 40.
The braking system illustrated in FIG. 1 is of the vacuum system variety, and a vacuum conduit or hose line 41 provides a vacuum drawn through an intake manifold of the engine 14 in well known manner. A check valve 42 prevents vacuum loss in the system when the engine 14 is not operating.
Vacuum drawn from the trailer controller 17 is routed through the hose disconnect device 43 and trailer conduit 4~.
As explained above, the trailer-mounted electro-mechanical brake control 17 systematically and infinitelyvaries, over a given range, fluid pressure and consequent braking action in the trailer brake system 16, in accordance with the sensed variation of the electrical signal transmitted by the controller 30. This braking action is provided by a trailer brake power booster unit 50.
1~83Z04 As illustrated in FIG. 3, the power booster unit 50 incLudes a power can 51 in which are defined two power chambe:rs 52 and 53, divided by a flexible diaphragm 54.
When an electrical signal is applied through electrical wiring 36 and 38 as described above, a valve 56 is positioned to permit air to be exhausted from one of these chambers 52 through a stub line 57 into a vacuum supply chamber 60. This supply tank 60 accommodates repeated braking action or surges in trailer brake vacuum demand. Air entering the vacuum supply tank 60 is drawn off by the vacuum conduit 44. Simultaneously, air is drawn from the second power can chamber 53 through a connector line 63 and safety check valve 64 to the vacuum con- `
duit 44. The check valve 64 serves to prevent vacuum loss in the second chamber 53 in the event of inadvertent vacuum con-duit parting or other system failure.
Appropriate alteration of the electrical signal in the electrical wiring 3~ repositions the valve 56 to close off the vacuum stub line 57 and open an air inlet port or line 66 so as to admit air into the first pswer can chamber 52. When this occurs, the diaphragm 54 moves (to the right as shown in FIG. 3) and correspondingly moves an interconnector 68. This interconnector 68 forms part of or is attached to a piston rod 70 extending from a trailer hydraulic master brake cylinder 71.
Movement of the piston rod 70 causes corresponding motion of the piston 72 and consequent increase or decrease in hydraulic pressure within the trailer system brake line 16. Changes in this brake system hydraulic pressure serves to operate the trailer brakes 74, which here are of the hydraulic disc type.
A manually operated brake release valve 75 is pro-vided to admit ambient-pressure air into the second power can chamber 53 so as to move the diaphragm in a direction causing brake release when desired. This valve thus permits the trailer brakes to be released for repositioning or other trailer movement of a limited nature even though the trailer may be disconnected from the towing unit.
A modified embodiment of the invention is shown in FIG. 2, and is especially adapted for use in towing vehicles 10 which are provided with a diesel engine 80, or some other type which does not provide a vacuum source. In addition, the embodiment illustrated in FIG. 2 can be used for any other in-stallation where it is believed undesirable to utilize a vacuum created by the power plant 80. Here, depressing the towing vehicle brake pedal 20 actuates the transducer 30 as described above. However, an electrically driven vacuum supply pump 85 is mounted upon the trailer 11, and exhausts the vacuum supply 2~0 tank 60 through a normally closed check valve 86. This pump 85 is driven by an appropriate motor 87; the motor 87 is, in turn, energized when necessary by a low pressure vacuum switch 88 which senses vacuum in the tank 60 through a tap line 89.
Power is supplied to both the switch 88 and the motor 87 through an appropriate electrical line 92 and breakaway plug 93 from a battery/generator or alternator combination 94 mounted upon the towing vehicle 10. An appropriate breakaway cable 100 secured at one end 101 to the towing vehicle 10 can be used to energize an electric breakaway switch 102 so as to operate the solenoid valve 56 in the event of inadvertent physical disconnection of the towing vehicle 10 from the trailer 11.
When the breakaway switch 102 operates the solenoid valve 56, air is admitted into the power can 50 to apply the trailer brakes 74, as described above.
_ g _ ~ .
1083Z0~
ber, so as to move the diaphragm interconnector means and vary the fluid pressure in and resultant braking action of the trailer brake system in accordance with diaphragm movement, and a fluid pressure supply means for creating a given, nor-mally equalized absolute fluid pressure in the power booster chambers. The control further includes safety valve means for altering the fluid pressure in one power booster chamber rela-tive to the other chamber and thereby providing braking action in the trailer braking system in response to a fluid pressure failure in the fluid pressure supply means, and a selectively operable brake release valve connected to the other of the power booster chambers so as to admit a fluid into the other chamber so as to re-equalize the pressure on the diaphragm and release the trailer braking system from further braking action, Other objects and advantages of the invention will be-come apparent upon reading the following detailed description .. . . .
~083ZV~ -and upon reference to the drawings. Throughout the drawings, like reference numerals refer to like parts.
Brief Description of the Drawin~s FIGURE 1 is a schematic diagram showing a novel brake system embodying the present invention;
FIG. 2 is a schematic diagram similar to FIG. 1 showing a modified version of the novel brake system; and FIG. 3 is a schematic diagram of a trailer brake power unit, an associated trailer brake master cylinder, and related apparatus.
Detailed Description While the invention will be described in connection with preferred embodiments, it will be understood that it is not intended to limit the invention to these embodiments.
On the contrary, it is intended to cover all alternatives, modifications and equivalents included within the spirit and scope of the invention and as defined by the appended claims.
Turning first to FIGURE 1 there is shown, in sche-matic form, an embodiment of the present novel braking system in use with a towing vehicle 10 and towed trailer 11. In gen~ral, the towing vehicle 10 carries an engine 14 for pro-pelling the towing vehicle 10 and the trailer 11. A towing vehicle brake system 15 selectively energizes associated :1083'~0~ -brakes (not shown). Mounted within and upon the trailer 11 is a trailer fluid brake system 16, and a control 17 mounted in and upon the trailer 11 which energizes and controls the trailer fluid brake system 16.
More specifically, when a driver of the towing vehicle 10 desires to retard its progress, he depresses a brake pedal 20 in well known manner. If the brakes on the towing vehicle 10 are of the hydraulic variety, and are of the "power brake" type, a power booster 21 is energized and actuates a hydraulic brake master cylinder 22. Appropriate hydraulic pressure is directed to towing vehicle rear wheel brakes through a hydraulic line 23, and to front wheel brakes through another line 24. Brake warning lights and other de-vices can be actuated through an appropriate switch 25.
An electromechanical transducer control 30 mounted on the towing vehicle 10 is energized by increased hydraulic pressure through an interconnector line 31. To provide a smooth infinitely controllable braking action to the trailer.
11 in accordance with the invention, this controller 30 modulates the towing vehicle hydraulic brake system brake pressure, and provides a correspondingly modulated electrical signal which varies systematically in accordance with fluid pressure experienced in the towing vehicle brake system inter-connector line 31. A manual override switch 32 can be included if desired to operate the trailer braking system 16 directly 108320~ .
Erom the towing vehicle 10. Appropriate electrical lines 33 and 34 connect the controller 30 to the towing vehicle elec-trical system battery or engine-driven generator, and to the system electrical ground, respectively. The electrical signal is transmitted by the controller 30 along appropriate wiring 36 through a quick-disconnect plug 37 and trailer wiring 38 to the trailer brake controller 17 mounted upon the trailer 11.
To maintain a common electrical ground, a wire 39 electrically interconnects appropriate grounding members of the trailer 11 and towing vehicle 10 through a ground wire interconnect plug 40.
The braking system illustrated in FIG. 1 is of the vacuum system variety, and a vacuum conduit or hose line 41 provides a vacuum drawn through an intake manifold of the engine 14 in well known manner. A check valve 42 prevents vacuum loss in the system when the engine 14 is not operating.
Vacuum drawn from the trailer controller 17 is routed through the hose disconnect device 43 and trailer conduit 4~.
As explained above, the trailer-mounted electro-mechanical brake control 17 systematically and infinitelyvaries, over a given range, fluid pressure and consequent braking action in the trailer brake system 16, in accordance with the sensed variation of the electrical signal transmitted by the controller 30. This braking action is provided by a trailer brake power booster unit 50.
1~83Z04 As illustrated in FIG. 3, the power booster unit 50 incLudes a power can 51 in which are defined two power chambe:rs 52 and 53, divided by a flexible diaphragm 54.
When an electrical signal is applied through electrical wiring 36 and 38 as described above, a valve 56 is positioned to permit air to be exhausted from one of these chambers 52 through a stub line 57 into a vacuum supply chamber 60. This supply tank 60 accommodates repeated braking action or surges in trailer brake vacuum demand. Air entering the vacuum supply tank 60 is drawn off by the vacuum conduit 44. Simultaneously, air is drawn from the second power can chamber 53 through a connector line 63 and safety check valve 64 to the vacuum con- `
duit 44. The check valve 64 serves to prevent vacuum loss in the second chamber 53 in the event of inadvertent vacuum con-duit parting or other system failure.
Appropriate alteration of the electrical signal in the electrical wiring 3~ repositions the valve 56 to close off the vacuum stub line 57 and open an air inlet port or line 66 so as to admit air into the first pswer can chamber 52. When this occurs, the diaphragm 54 moves (to the right as shown in FIG. 3) and correspondingly moves an interconnector 68. This interconnector 68 forms part of or is attached to a piston rod 70 extending from a trailer hydraulic master brake cylinder 71.
Movement of the piston rod 70 causes corresponding motion of the piston 72 and consequent increase or decrease in hydraulic pressure within the trailer system brake line 16. Changes in this brake system hydraulic pressure serves to operate the trailer brakes 74, which here are of the hydraulic disc type.
A manually operated brake release valve 75 is pro-vided to admit ambient-pressure air into the second power can chamber 53 so as to move the diaphragm in a direction causing brake release when desired. This valve thus permits the trailer brakes to be released for repositioning or other trailer movement of a limited nature even though the trailer may be disconnected from the towing unit.
A modified embodiment of the invention is shown in FIG. 2, and is especially adapted for use in towing vehicles 10 which are provided with a diesel engine 80, or some other type which does not provide a vacuum source. In addition, the embodiment illustrated in FIG. 2 can be used for any other in-stallation where it is believed undesirable to utilize a vacuum created by the power plant 80. Here, depressing the towing vehicle brake pedal 20 actuates the transducer 30 as described above. However, an electrically driven vacuum supply pump 85 is mounted upon the trailer 11, and exhausts the vacuum supply 2~0 tank 60 through a normally closed check valve 86. This pump 85 is driven by an appropriate motor 87; the motor 87 is, in turn, energized when necessary by a low pressure vacuum switch 88 which senses vacuum in the tank 60 through a tap line 89.
Power is supplied to both the switch 88 and the motor 87 through an appropriate electrical line 92 and breakaway plug 93 from a battery/generator or alternator combination 94 mounted upon the towing vehicle 10. An appropriate breakaway cable 100 secured at one end 101 to the towing vehicle 10 can be used to energize an electric breakaway switch 102 so as to operate the solenoid valve 56 in the event of inadvertent physical disconnection of the towing vehicle 10 from the trailer 11.
When the breakaway switch 102 operates the solenoid valve 56, air is admitted into the power can 50 to apply the trailer brakes 74, as described above.
_ g _ ~ .
Claims (21)
1. A brake system for towing a vehicle and trailer, comprising a towing vehicle fluid brake system, an electro-mechanical transducer connected to the towing vehicle fluid brake system for developing an electrical signal which varies proportionately in accordance with fluid pressure experienced in the towing vehicle brake system, a trailer fluid brake system, and an electromechanical control electrically connec-ted to the transducer for proportionately varying the fluid pressure and consequent braking action in the trailer brake system in accordance with the variation in the electrical sig-nal, said control including a power booster having a diaphragm between two chambers as defined within the power booster, a diaphragm interconnector interposed between the diaphragm and said trailer fluid brake system, valve means responsive to said electrical signal for altering pressure in one of the power booster chambers, relative to the other chamber, so as to move the diaphragm interconnector means and vary the fluid pressure in and resultant braking action of the trailer brake system in accordance with diaphragm movement, a fluid pressure supply means for creating a given, normally equalized absolute fluid pressure in the power booster chambers, safety valve means for altering the fluid pressure in one power booster chamber relative to the other chamber and thereby providing braking action in the trailer braking system in response to a fluid pressure failure in the fluid pressure supply means, and a selectively operable brake release valve connected to the other of said power booster chambers so as to admit a fluid into said other chamber so as to re-equlize the pressure on the diaphragm and release the trailer braking system from further braking action.
2. A brake system according to claim 1 wherein said fluid pressure supply means includes a fluid pressure pump, and a fluid pressure-accommodating supply tank, the supply tank being mounted on said trailer for maintaining the abso-lute fluid pressure created in at least one power booster chamber.
3. A brake system according to claim 2 wherein said fluid pressure pump is mounted on said towing vehicle, and including fluid pressure conduit means connecting the towing vehicle pump and the trailer-mounted supply tank.
4. A brake system according to claim 3 including quick disconnect means for disconnecting the fluid pressure conduit means at a point intermediate said fluid pressure supply tank and said fluid pressure pump.
5. A brake system according to claim 1 wherein said valve means include solenoid means producing a mechanical move-ment in response to said electrical signal, and a valve member moveably connected to the solenoid means for opening and closing motion in response to the solenoid means mechanical movement for altering the absolute fluid pressure in one of the power booster chambers.
6. A brake system according to claim 5 wherein said two power booster chambers are normally maintained at rela-tively equalized absolute fluid pressures, and wherein said valve member operates to admit a fluid into one of said cham-bers so as to unequalize the fluid pressure on the diaphragm and operate the trailer braking system.
7. A brake system according to claim 1 wherein said trailer brake system includes master cylinder means mechanically linked to said power booster diaphragm, movement of the diaphragm varying brake fluid pressure in the trailer braking system proportionately to brake fluid pressure in said towing vehicle brake system.
8. A brake system according to claim 1 including man-ually operated override means for actuating the trailer brake system braking action regardless of towing vehicle brake sys-term actuation or transducer-developed electrical signals.
9. A brake system according to claim 1 wherein said electromechanical transducer includes means for systematically varying the electrical signal continuously and infinitely over a given range, and wherein said electromechanical control in-cludes means for systematically varying the trailer brake system fluid pressure and consequent braking action in a con-tinuous and infinitely variable manner over a given range in accordance with the electrical signal.
10. A brake system according to claim 1 wherein said trailer fluid brake system includes disc brakes responsive to fluid pressure in the trailer brake system to retard rota-tion of trailer wheels.
11. A brake system a cording to claim 1 including means for producing a vacuum in each of the power booster chambers and manual brake release valve means interposed between the power booster and the fluid pressure supply means for releasing the vacuum in said other power booster chamber and thus pro-viding braking action in the trailer braking system on demand.
12. A brake system according to claim 11 wherein said fluid pressure supply means comprises vacuum take-off means fitted to a towing vehicle engine intake manifold, and vacuum conduit means interconnecting the vacuum take-off means and said power booster chambers.
13. A brake system according to claim 11 wherein said fluid pressure supply means comprises vacuum pump means car-ried on the trailer for producing a vacuum in the power boos-ter chambers.
14. A brake system according to claim 13 including power means for operating said vacuum pump.
15. A brake system according to claim 14 including external electrical supply means carried on said towing vehicle for supplying said power means with electrical power for op-eration.
16. A brake system according to claim 15 including electrical conduit means for transmitting the electrical power from the electrical supply means on the towing vehicle to said vacuum pump power means on said trailer.
17. A brake system according to claim 11 including safety means for actuating said manual valve means in the event of electrical disconnection of the trailer from the towing vehicle.
18. A brake system according to claim 11 including vacuum supply tank means functionally interposed between said valve means and said means for producing a vacuum in each power booster chamber.
19. A brake system according to claim 11 including brake release valve means for releasing the trailer brakes upon demand.
20. A brake system according to claim 11 wherein said electromechanical transducer includes means for systematically varying the electrical signal continuously and infinitely over a given range, and wherein said electromechanical control in-cludes means for systematically varying the trailer brake system fluid pressure and consequent braking action in a con-tinuous and infinitely variable manner over a given range in accordance with the electrical signal.
21. A brake system according to claim 11 wherein said trailer fluid brake system includes disc brakes responsive to fluid pressure in the trailer brake system to retard rota-tion of trailer wheels.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA289,900A CA1083204A (en) | 1977-10-31 | 1977-10-31 | Trailer brake system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA289,900A CA1083204A (en) | 1977-10-31 | 1977-10-31 | Trailer brake system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1083204A true CA1083204A (en) | 1980-08-05 |
Family
ID=4109904
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA289,900A Expired CA1083204A (en) | 1977-10-31 | 1977-10-31 | Trailer brake system |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1083204A (en) |
-
1977
- 1977-10-31 CA CA289,900A patent/CA1083204A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |