Detailed explanation of the concept and classifica

Detailed explanation of the concept and classification of the brake of hoisting machinery

the safety regulations of hoisting machinery stipulate that the hoisting, luffing, running and rotating mechanisms of power driven cranes must be equipped with brakes. The brake uses the friction principle to realize the mechanism braking. The friction parts of the brake press the brake wheel on a certain root of the mechanism with a certain action force to produce braking torque. Using this braking torque, the torque generated by the object mass and inertia force is reduced until the two torques are balanced to meet the requirements of speed regulation or braking

the brakes used by cranes are various. According to the structural characteristics, it can be divided into three types: block type, belt type and disc type, of which block type is used most. According to the working state, block type can be divided into normally closed type and normally open type. The normally closed brake is often closed. When the mechanism works, it can be released by the action of external forces such as electromagnet or electric hydraulic pusher. On the contrary, the normally open brake is often in a released state, and it can be closed only when an external force is applied. From the perspective of work safety, all working mechanisms of the crane should adopt normally closed brakes

types and structures of brakes

the common brakes of bridge cranes are: short stroke electronic block brake, long travel tile brake, hydraulic push rod tile brake, hydraulic electromagnetic tile brake, etc

1. Block brake

① short stroke electronic block brake: short stroke brake has simple structure, light weight and fast braking. The disadvantages are large impact and noise, short service life, small braking torque, and sometimes residual magnetism. It is only applicable to the lifting mechanism. If there is no explosion-proof type and DC power supply is used, the electromagnet needs to be replaced

② long travel block brake: this kind of brake has the advantages of large travel, large braking torque and fast braking. The production capacity will reach 600million ampere hours next year, with little residual magnetism, which is relatively safe. The disadvantages are that the impact and noise are large, the service life is not long enough, there are many and complex components, the volume and mass are large, and the efficiency is low. It is only suitable for lifting mechanisms. Reverse time node

③ electric hydraulic block brake: replace the electromagnet of long travel block brake with hydraulic electromagnetic block, including YWZ (hydraulic push rod) and ydwz (hydraulic electromagnet). YWZ type has stable braking, no noise and small volume. It is better for operating mechanism and rotary mechanism. Due to its slow braking and stopping action, it is not suitable for the lifting mechanism to prevent hook slipping. Ydwz type has good performance in all aspects, and it does not need to be adjusted frequently. It only needs DC power supply

2. Belt brake: when the overall dimension is limited and the braking torque is required, it can be considered to choose belt brake, which is often used on mobile cranes. The disadvantage of the belt brake is its low safety, and the breaking of the brake belt will cause serious consequences

3. Disc brake: disc brake is widely used due to its large torque, small overall size, large friction area and small wear. Disadvantages of disc brake: it is mainly that the electromagnet coil temperature rises, which is easy to heat, impact, noise and parts are easy to be damaged

4. Conical brake. The brake ring and brake wheel of the conical brake are conical. The conical brake is a part of the conical motor, Cone maoxiaoming said, "when you are driving, the reason why the rotor and stator of the cone-shaped motor are designed and made into a cone is to obtain a cone-shaped brake with simple and light structure, convenient production, assembly and adjustment, and inseparable from the motor. The cone-shaped brake is widely used by electric hoists. CD, as, DH electric hoists all use cone-shaped brakes