TWIFLEW UK Brake VKSD96

TWIFLEW UK Brake VKSD96

(1) Regardless of the reason for the power supply or control circuit power failure of the elevator, the brake should generate sufficient braking torque to reliably stop the car. Therefore, braking torque is its main parameter, used to ensure that the elevator in operation stops at the required deceleration according to standards.

TSG T7001-2009 "Rules for Supervision, Inspection and Periodic Inspection of Elevators - Traction and Forced Drive Elevators" Annex A, item 8.10 requires: "When the car is unloaded and running at normal speed, the power supply to the motor and brake should be cut off, and the car should be reliably stopped without obvious deformation or damage

During inspection, when the car is unloaded and running at normal speed up to the upper part of the travel, disconnect the main power switch and check the car's braking and deformation damage.

During inspection, the elevator car should carry 125% of the rated load and move downwards at normal operating speed. When the elevator car reaches a lower level station, the power supply to the motor and brake should be cut off, and the elevator car should be reliably stopped without obvious deformation or damage. Usually, acceleration and deceleration testers are used on site to test and record values, and the instrument can display the average deceleration.

(2) Article 12.4.2.1 of GB7588-2003 requires: "All mechanical parts of the brake that participate in applying braking force to the brake wheel or disc should be assembled in two groups. If one group of components does not work, there should be sufficient braking force to slow down the car carrying the rated load and descending at the rated speed. The iron core of the electromagnetic coil is considered a mechanical component, while the coil is not." This standard can be understood as "All components of the brake that participate in applying braking force to the brake wheel or disc should be brake pads and compression springs or heavy hammers that generate braking force, which should be divided into two groups according to the above provisions. At the same time, the iron core of the electromagnet that exerts braking force on the brake wheel opposite to the compression spring and has the opening effect must also be correspondingly matched. Divided into two groups, and there should be no correlation between the two groups of iron cores, their actions should be independent. The regulation does not emphasize two coils. If two coils are set, it means two sets of brakes. ”Therefore, during the appearance inspection, the hardware mentioned above should meet the requirements. During the functional test, it is considered to open one set of brake pads, causing the car carrying the rated load to descend at the rated speed to pull the brake and cut off power, and mutually determine whether the other set of brake pads is slowing down the car.

As this requirement isTWIFLEW UK Brake VKSD96The elevator manufactured according to the requirements of GB7588-1995 usually only has one iron core for the brake electromagnet, so it can only be used as one set of brakes instead of two sets, which does not meet the requirements of this condition. Therefore, in actual inspection, the method of "new ladder, new standard, old ladder, old standard" is generally followed according to the date of appearance.

(3) According to Article 12.4.2.4 of GB7588-2003, "The elevator drive host equipped with a manual emergency operation device should be able to release the brake by hand and maintain the release state with a continuous force." During inspection, disconnect the main power supply of the elevator, install the disc wheel, and have 1-2 maintenance personnel hold the disc wheel. Another maintenance personnel use a brake release wrench to release the brake and conduct a rescue disc wheel release test. Of course, due to the different types of traction machines from various manufacturers, the operating methods may vary slightly. If it is an operating device with an operating force greater than 400N or an elevator without a machine room that is difficult to manually turn, an emergency electric operation electrical operating device should be installed.

(4) For block brakes, Article 4.1.10 of GB10060-1993 "Code for Acceptance of Elevator Installation" requires: "The brake action should be flexible, and the brake shoes on both sides should be tightly and evenly attached to the working surface of the brake wheel during braking. When releasing the brake, they should be synchronized to leave, and the average gap at the four corners should not exceed 0.7mm on both sides." Therefore, during inspection, it is necessary to check the rotating parts of the brake, and each pin shaft should rotate flexibly; When powered on or off, the moving iron core should operate without any jamming; The brake arms on both sides of the brake should move in unison, that is, simultaneously opening or holding the brake. When checking that the average gap between the four corners of the brake is not greater than 0.7mm on both sides, short-circuit the upper limit switch, upper limit switch, and buffer switch, and slowly lift the empty car to fully press the counterweight onto the buffer. Cut off the main power supply of the elevator, manually energize the brake control coil, open the brake, measure the gap between the brake pad and the brake wheel with a feeler gauge, and the average gap at the four corners should not exceed 0.7mm. It should be noted that the standard requires the average gap.

(5) The wear of brake pads (or brake pads) should be checked regularly. If the wear is large, it will reduce the contact surface between the brake shoes (or brake pads) and the brake wheels (discs), resulting in a decrease in braking torque and causing unsafe hazards such as rolling. Figure 1 shows a severely worn brake shoe. Structurally, the force exerted by the brake pad on the brake wheel or brake disc should be symmetrical, without generating additional loads on the motor shaft and worm shaft. The brake shoe material should be non flammable and have a certain heat capacity to ensure that the friction coefficient remains basically unchanged during heating. It must be made of materials with sufficient strength and good quality, and harmful materials such as asbestos are not allowed to be used.

(6) Brake noise should be detected separately

The general working principle of the braking system is to use the mutual friction between non rotating components connected to the vehicle body (or frame) and rotating components connected to the wheels (or transmission shaft) to prevent the rotation or tendency of the wheels.

A simple hydraulic brake system diagram can be used to illustrate the working principle of the brake system. A metal brake drum with an inner circular surface as the working surface is fixed on the wheel hub and rotates together with the wheel. On the fixed brake base plate, there are two support pins that support the lower ends of two arc-shaped brake shoes. The outer surface of the brake shoe is equipped with friction plates. The brake base plate is also equipped with hydraulic brake wheel cylinders, which are connected to the hydraulic brake master cylinder installed on the frame through oil pipe 5. The piston 3 in the master cylinder can be operated by the driver through the brake pedal mechanism.

When the driver steps on the brake pedal to compress the brake fluid, the wheel cylinder piston presses the brake shoes towards the brake drum under hydraulic pressure, causing the brake drum to reduce its rotational speed or remain stationary.

When learning about the braking system of a certain car model, you may often hear the words "front disc and rear drum" or "front disc and rear drum". So, what does it mean? Some readers have asked questions about car braking systems through email, such as the difference between disc brakes and drum brakes, the difference between ventilated discs and solid discs, and so on.

Many mid to low end car models with small engine displacements in the car market use a "front disc and rear drum" braking system, which means the front wheels use disc brakes and the rear wheels use drum brakes, such as the common FAW Volkswagen Jetta, Changan Suzuki Alto and Lingyang, BYD Flair, Dongfeng Yueda Kia Qianlima, Shanghai General Motors Sail, and so on. Let's first take a brief look at the drum brakes commonly used on the rear wheels.

The difference in practical application is very obvious, with disc brakes being better than drum brakes. Drum brakes and disc brakes each have their own advantages and disadvantages. In terms of braking effect, there is not much difference between disc brakes and drum brakes, because during braking, kinetic energy is converted into heat energy through braking. If the car is compact and lightweight, the rear wheels can be braked with drum brakes.

In terms of heat dissipation, disc brakes dissipate heat faster than drum brakes, and ventilated disc brakes have better heat dissipation effects; In terms of sensitivity, the disc brake will be higher, but in rainy days when the road is muddy, the braking effect will be greatly reduced when the brake drum is stuck with mud and sand, which is also the disadvantage of disc brakes; In terms of cost, drum brakes are lower than disc brakes and have a longer service life, so some mid to low end cars tend to use drum brakes, while models above mid to high end generally use four disc brakes.