Key (or trigger key) is widely used in the cord plug circuit, monitoring circuit, seat circuit and signal circuit of various racks of long-distance switching equipment.
Chinese name
Key
Foreign name
key
Alias
Key wrench
Definition
Various machines used in long-distance telephone switching equipment
The key can be divided into single throw and double throw according to its flipping position.The reed set of the key is fixed on the key frame according to the needs of the circuit, so pulling the key can make the reed set act and complete the connection of the circuit.There are many combinations of reeds, but basically the contact of reeds is composed of dynamic closing contact, static closing contact, conversion contact (opening before closing), and uninterrupted conversion contact (closing before opening).
The key shall be adjusted according to the technical requirements of each equipment.[1]
clean
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The key device of long-distance telephone switching equipment provided by the factory is mostly plug-in type.However, some old equipment still has fixed devices.The former can be easily loaded and unloaded during the pre inspection of keys.For the latter, during the pre inspection of keys, during the operation, not only the wiring, routing angle and bending potential of the loaded and unloaded keys must be kept neat and beautiful, but also the adjacent keys or other components on the left and right must be paid attention to, so as to avoid breaking or damaging the wire ends and creating obstacles.After the key of plug-in device is removed from the machine table, use an appropriate screwdriver to unscrew the fixing screws of the key holder and the reed set to separate the key holder and the reed set.For single contact keys, it is better to mark the key holder according to the position of the original device reed set to avoid mutual adjustment of direction. Because the keys have certain habits in daily use, it is easier to adjust when the keys are disassembled, cleaned and restored for assembly.The position of the key holder of the double contact key is fixed, so it is not subject to this restriction.Use a brush to remove the dust on the removed key holder and reed set, and then use a toothbrush to dip a small amount of gasoline andcarbon tetrachlorideThe mixed solution shall be brushed clean and then wiped dry with a clean cloth.In addition, the rubber is also cut into thin pieces (advanced drawing rubber is selected) to wipe the reed and contact, and the effect is also very good.Then check whether the bakelite roller of the key carrier is worn.Whether the pin for fixing the key switch is loose and whether the switch is pulled flexibly.The surface of bakelite roller can be wiped with polishing wax.For the reed set, check whether the set screw of the reed set is tightened, whether the reed is arranged neatly, whether the reed has cracks, whether the contacts are aligned, and whether the contacts fall off or have too large pits.If any undesirable condition is found, it shall be repaired or replaced one by one, and then the reed set shall be restored and fixed to the key rack, and then the key shall be adjusted.[1]
Adjustment requirements
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Single contact key
oneCamThe rotation shall be flexible and there shall be no friction with the key carrier.The clearance between the cam and the main spring shall not be less than 0.75 mm;
2. The key knife switch does not shake from left to right, and it can automatically recover when it moves 30 degrees forward and backward respectively.The thrust to pull the key knife switch back to its original position from the self-locking side shall not be less than 50g.
3. The roller shall be able to rotate flexibly and contact the main spring with its cylinder. In the middle position, the roller shall fall on the main spring and keep the key handle vertical.
4. The center line of all reeds shall be nearly vertical to the key panel, and the two groups of reeds shall be arranged in parallel.
5. The minimum clearance for contact disconnection shall not be less than 0.4 mm.When the contacts are closed, the pressure between the contacts shall not be less than 50g.When the key knife switch is pulled, before the contact is separated, the offset distance (or tracking) between the internal contact spring of the key and the main spring shall not be less than 0.2mm.
6. The contact spring shall be kept flat and straight, and shall not be damaged or bent.The tip of each reed contact shall be completely within the range of its corresponding plane contact when the contact is closed.
7. When its opposite main spring acts, the curved contact spring shall lean against its locating lining.The maximum pressure between the main spring and the spring at the curved point (when turning the key knife switch to make the opposite spring set act) is 300g.
Double contact key
1. The camshaft shall rotate flexibly in the key frame groove without shaking, and there shall be no friction barrier when pulling the key knife switch.
2. The bakelite wheel shall rotate flexibly on the roller shaft and contact the main spring with its cylindrical surface.When the cam assembly is in the middle position, the bakelite roller should not be pressed on the active spring, and a clearance of 0.1mm should be left.
3. When the key is in the static position, the key handle shall be vertical without deflection.When the key knife switch is pulled, the self-locking side should not spring back, and the self-healing side should immediately spring back.The pulling force required for the key to pull to either side at the neutral position shall be determined according to the number of reeds in the pulling direction.Generally speaking, the pulling force of the keys of 12 reed sets is 100~600g.100~800g for more than 12 reed groups.The pulling force when the key is pulled back to neutral from any direction shall not be less than 100g.
fourreedIn the group, the contact center of the reed opposite to the contact shall be aligned, and the maximum deviation shall not exceed 0.3mm.The pressure between the closing contacts of the contact group shall not be less than 60g.
To adjust the keys, use flat nose pliers to bend the reeds in a circular arc along the length of the cabinet. Do not bend the reeds randomly to avoid damage.The tension gauge (or elastic gauge) can be used to measure the pressure of the key spring.
After checking and adjusting according to the above requirementsMultimeterMeasure whether there is any collision between the reed set and the key rack, sort out the wiring, restore the key to the machine (or rack), and then conduct the performance test.[1]
