Application of Pedal Brake System in Crane

2017-07-10

At present, the crane operating mechanism usually adopts the regular closed type brake. When the crane needs to stop, the running mechanism motor will be cut off, while the brake is also cut off. In this way, the crane will stop working. But in some enterprises whose equipment manufacturing and installation positioning is not unique, and for some cranes whose operating mechanism does not include the function of adjusting speed, the process of counterpoint often requires repeated jogging to complete, and during the process of counterpoint the lifted objected is easy to swing due to brake too much. In order to improve efficiency and operational flexibility, operators often release the operating mechanism brake of the crane. This phenomenon is very common while it is not complied with safety regulations which hidden security risks; and it will also cause great impact and damage to the operating mechanism of crane. Especially if there is trouble for the power supply, it will lead the crane to slide out of control inevitably, and it will even lead to load collision. So in order to both ensure the flexibility of operating the crane, smaller swing of the load, but also to ensure the safety of the crane, we adopt the pedal brake system in the crane operating mechanism.
Structure of the System and Working Principle
For the traditional products, operating mechanism of the crane is usually composed of trolley group, low-speed floating shaft, low speed half-teeth coupling, reducer, brake, brake wheel coupling, high-speed floating shaft, brake wheel coupling, high-speed half-tooth coupling, motor and other components. See as Figure 1. This traditional braking system usually adopts closed brake form, while the brake working state and handle are interlocked. Under the regular operating state, the brake is open when the handle leaves the zero position; and the brake is locked immediately when the handle returns to zero position. When the brake is working normally, it can ensure the safety of the operating mechanism. But it is not convenient to operate, difficult to counterpoint, and it cannot complete the work quickly and effectively even the operation is combined with multiple jogs.
In the pedal brake system, we set two different operating modes of the brake: It normally open mode and normally closed mode. It sets the pot switch on the pot as a given inverter through the inverter to control the hydraulic brake putter. Analog of the potentiometer will change along with the operating position of the pedal brake. In this way, it can control the inverter to work at different speeds. And it will drive the hydraulic putter work in different states in order to achieve the brake torque control. In normal conditions, the working brake is in the open state. When there is need of brake, alignment, it will control the operation according to the requirements of the brake torque through the foot switch in the driver's room. The braking speed and braking torque of the brake are interlocked with the force of the foot switch. The greater force the foot switch gets (the position is deep), the faster the brake is, and the greater the braking torque; the smaller force the foot switch gets (the position is shallow), the slower the brake is, and the smaller the braking torque; The torque control method is similar to vehicle brake, it will achieve accurate alignment, and smaller impact.
Safety control principle: Safety brake adopts normally closed brake; the safety brake will open immediately when the operating mechanism handle left the zero position. And the driver can release the foot switch when the operating mechanism handle is back to zero position is delay after the brake. When the brake is in a state of failure because of out of power (Unexpected power outage and normal power outage) or standby time is too long, the safety brake will automatically holds the brake to protect the safety of the crane. When there is an emergency, the driver can press the emergency stop button; the safety brake will work immediately, and play a safe role for the crane.