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CN(Shenzhen Special Equipment Safety Inspection Research Institute, Shenzhen 518029, Guangdong, China) Explains the methods, standards, and inspections for adjusting the elevator brake clearance. Because of the adjustment of elevator brake clearance, it is directly related to safe operation. Each one is engaged in elevator installation, Maintenance personnel and inspection and inspection personnel should pay enough attention to elevator brake shoe wear and gap adjustment issues.
With the increase in the benefits of high-rise buildings in China, elevators are widely used as an important transportation tool, and the smooth operation and precise stop of elevators are inseparable from the reliable operation of elevator brakes. The core component of elevator brakes is the brakes. The electromagnetic brake system, the elevator brake system is the elevator’s most important safety and security components, it is installed next to the motor, in the brake shaft where the motor shaft and the worm shaft are connected, it is the brake system that makes the elevator Keep the elevator car at rest while standing. However, the brake gap is the key to ensuring brake braking. This paper starts from the working principle and structural principle of the brake holding system, expounds the methods, standards and inspections for adjusting the elevator brake clearance, and provides some references for elevator maintenance personnel.
1 The working principle of the elevator brake The elevator brake is mainly composed of two parts: brake electromagnet and brake shoe brake.
The brake electromagnet consists of three parts: iron core, armature and coil. Shoe brakes include brake wheels, brake shoes and springs. The brake wheels and the motor are mounted on the same shaft.
The elevator’s automatic system is an electromechanical brake (friction type). The main components of this system are the electromagnets, brake arms, springs, brake wheels, and brake pads.
When the elevator is in a stagnant state, the traction motor of the elevator disconnects the switch or the contactor, the motor loses power, and the electromagnetic brake coil also loses electricity. The armature is separated from the core under the action of the spring tension, and no current passes, and the brake magnet does not Attractive, but under the action of the brake spring, the brake pad will tightly control the brake wheel, the motor is braked and the coils of the motor and brake are stopped, so as to keep the elevator stationary; the elevator starts During operation, the motor is in the energized state, so that the electromagnetic force generated will push the brake pads open, the elevator traction motor is connected to the power supply, and the electromagnetic brake coil is also energized, the armature pulls in and pulls in, overcoming the pull of the spring to make the brake The brake shoe is separated from the brake wheel, and the running condition of the elevator remains good. When the elevator rises or falls on a specified floor, the current of the motor rapidly disappears, and the corresponding electromagnetic force will disappear with it, so that the brake pads and the brake wheel are tightly pressed together by the brake spring, so that The elevator fell on the corresponding floor. When the elevator works normally, the current passes through the brake coil and the magnetic core of the brake magnet is magnetic, causing the brake spring to lose pressure, the brake pad and the brake spring are separated, the brake wheel and the brake pad are separated, thus ensuring the elevator The normal operation and operation.
1.3 The working characteristics of the electromagnetic brake brake The elevator brake mainly presents two kinds of conditions: loose brake and holding brake. When the elevator is in normal operation, the brake is released to keep the elevator running; when the elevator has a blackout and stops operation , Brake brake, maintain the safety and stability of the elevator. Its advantages are strong braking force, safety and reliability, and no accident caused by sudden power failure. The disadvantage is that the brake has a large volume, the brake wear is severe, and vibration is generated when braking rapidly.
2Adjustment of the gap of the motor holding brake When the holding brake is in normal operation and the wear of the holding core is not serious, the gap between the holding core and the magnet case is generally 20mm. At the same time, two holding brake levers support the weight of the brake core on average. During the inspection process, the inspector manually opened the brake and checked the brake lining clearance with a feeler gauge to ensure that the feeler gauge with a thickness of 0.15 mm could pass very smoothly and the 0.25 mm gauge feeler could pass through. The elevator is operated in manual mode or at detection speed and it is verified that the holding brake shoe has an average clearance of 0.125 to 0.250 mm from the brake disc. Use the brake to open the adjusting bolts. Set the brake shoes open. The gap between each brake shoe and the brake disc must be the same.
2.2 Method of adjustment of the brake gap 2.2.1 Preparation of clearance adjustment Since the elevator belongs to special equipment, it is necessary to operate strictly in accordance with the standard during the process of adjusting the gap of the brake. First, the elevator should be stopped, and the mechanical and electrical shutdown confirmation must be completed. The power switch is locked and the “is being repaired” and “non-started” warning signs are hanging.
Check the remaining thickness of the brake lining (ie, the minimum thickness of the brake lining) carefully before adjustment and check the protective disc. If the edge of the protective disc has touched the positioning pin mark, the brake disc must be replaced.
Adjust the air gap of the brake: Tighten three (four) bolts to an air gap of zero, reversely loosen the bolts to an angle of 120°, and check the brake clearance with a feeler gauge (check at least three points). And in accordance with the provisions of the value; not correct, please re-adjust; but due to the brake model is different, the reverse loosening angle, the brake gap is not the same, in the adjustment process according to the standard air gap provided by the elevator manufacturer to adjust. In the adjustment, the brake switch mounting bracket will be removed and the fixed position of the brake switch will be adjusted to ensure that the switch will still have a stroke of 0.5 to 1.0 mm after the switch is actuated by pressure when manually opening the brake. There must be a clearance of about 2 to 2.5 mm between the brake discs. In particular, check the suction in the hot state of the brake. When the power is on, the cores on both sides of the brake are synchronized, but the stroke of the brake after adjustment is completed (brake lever The moving distance at power-on) should not exceed 3.5mm. The basis for adjusting the brake gap is that the wear of the brake shoe does not exceed the limit. If the limit of the gap between the two moving cores cannot be adjusted for the structure, etc. Take measures to adjust while wearing. If the brake brake shoe wear does not exceed 1mm, the gap between the two moving cores will be reduced by 2.5mm. At this time, the gap between the two moving cores can be adjusted by adjusting both side adjusting screws (one side is turned out 1.25mm). Return to original size again. When the brake shoe wears, the gap between the brake shoe and the brake disc increases (that is, the two moving cores move outward respectively). In the adjustment, if there is no restriction on the outward movement of the brake shoe and the brake disc, no matter how much the amount of wear is, the brake arm will not be opened and the brake will fail. If there is a limit to the amount of outside movement of the brake shoe and the brake disc, the brake arm is opened.
2.3 After the brake gap clearance adjustment After the detection of the brake gap clearance is successful, the most commonly used detection method is the dynamic brake gliding test. After all initial adjustments are completed, a brake gliding test must be performed, such as a full-load safety gear test, counterweight balance factor, and so on.
In the test process, the car is fully loaded first, and the elevator is run down from the top of the hoistway. After the contract speed is reached, the car is stopped with an emergency stop switch to make the brake act, and both brake arms work at the same time. Record the gliding distance of the holding brake so that the gliding distance (tested using the PMT) meets the following requirements. Under normal circumstances, when the operating speed of the elevator is 1.0m/s, the full-load sliding distance is between 400 and 450mm; when the operating speed is 1.5m/s, the full-load sliding distance is between 1100 and 1200mm; the operating speed is 1.75m/s When the full-load coasting distance is between 1600 and 1700mm, if the detection exceeds this range, it can be considered that the brake adjustment is not successful and needs to be readjusted.
The adjustment of elevator brake clearance is directly related to safe operation. Every person who is engaged in elevator installation, maintenance, inspection and inspection should pay enough attention to the problem of elevator brake shoe wear and gap adjustment. At the same time, it is necessary to do frequent inspections. It is found that the wear of the brake shoes must be promptly replaced, and adjustment of the gap between the lights cannot guarantee the safe braking of the elevator.