The shaft mechanical brake is suitable for small and medium-sized ships that need to lock the stern shaft when the ship is stopped.

Definition and Function

The shaft mechanical brake is an important safety device in the ship shaft system. It is mainly used to enable the shaft system to quickly stop rotating when needed, thereby controlling the power transmission of the ship and achieving the braking of the ship. For example, when a ship docks, comes to an emergency stop, or encounters an unexpected situation, the shaft mechanical brake can use friction to prevent the rotation of the shaft by tightly gripping the shaft, allowing the ship to safely stop or decelerate.

Structural composition

Brake disc (or brake drum): This is one of the key components of the shaft mechanical brake system, and it is usually installed on the shaft system. A brake disc is generally a disc-shaped metal structure with a flat surface and good wear resistance, capable of withstanding the frictional force generated during braking. The brake drum is a cylindrical component. Their function is to provide a friction surface for the brake shoes (or brake pads) and achieve braking through contact with the brake shoes (or brake pads).

Brake shoes (or brake pads): made of friction materials, such as composite materials containing metal fibers, ceramics, and other components. The shape and size of the brake shoes (or brake pads) match the brake disc (or brake drum), and during braking, they will tightly contact the brake disc (or brake drum) under external forces, generating friction and slowing down or stopping the shaft system. These friction materials need to have a high coefficient of friction and good wear resistance to ensure braking effectiveness and service life.

Brake drive mechanism: mainly responsible for providing power to bring the brake shoe (or brake pad) into contact with the brake disc (or brake drum). Common drive mechanisms include hydraulic drive systems and pneumatic drive systems. The hydraulic drive system pushes the piston through the pressure of hydraulic oil, causing the brake shoe (or brake pad) to move; The pneumatic drive system utilizes the pressure of compressed air to achieve the same function. This driving mechanism can quickly and accurately control the application and release of brakes.

Brake spring (or reset device): used to restore the brake shoe (or brake pad) to its original position after braking is completed, so that the shaft system can operate normally again. The brake spring is usually a coil spring, which can provide sufficient elastic force to overcome the residual friction between the brake shoe (or brake pad) and the brake disc (or brake drum), and reset the brake device. Some reset devices may use other elastic components or mechanical structures to achieve the same function.

working principle

When it is necessary to brake the shaft system, the brake drive mechanism starts working after receiving the brake signal. For example, in a hydraulic driven shaft mechanical brake, hydraulic oil pushes the piston under pressure, and the piston drives the brake shoe (or brake block) to move towards the brake disc (or brake drum). After the brake shoes (or brake pads) come into contact with the brake discs (or brake drums), the rotational motion of the shaft system is hindered due to the frictional force between them. The magnitude of friction force depends on the positive pressure (controlled by the driving mechanism) between the brake shoe (or brake pad) and the brake disc (or brake drum), as well as the friction coefficient of the friction material. With the continuous action of friction, the speed of the shaft system gradually decreases and eventually stops rotating. After the braking is completed, the brake spring (or reset device) takes effect, pulling the brake shoe (or brake pad) back to its original position and releasing the braking state.

advantage

Reliable braking effect: The mechanical brake of the shaft system can effectively stop the rotation of the shaft system in a short period of time, and the braking process is stable. The friction braking method used can provide sufficient braking force to ensure that the ship can quickly brake when needed, ensuring the safety of the ship.

Fast response speed: Both hydraulic and pneumatic braking systems can quickly respond to braking signals. In emergency situations, the braking program can be quickly activated to bring the brake shoes (or brake pads) into contact with the brake discs (or brake drums), achieving rapid braking.

Good adjustability: By adjusting the pressure of the brake drive mechanism, the positive pressure between the brake shoe (or brake pad) and the brake disc (or brake drum) can be controlled, thereby adjusting the braking strength. This can flexibly control the braking effect based on the actual operating conditions of the ship, such as different ship speeds, loads, etc.

Disadvantages and countermeasures

Friction material wear problem: The friction material of the brake shoe (or brake pad) will gradually wear out during multiple braking processes, which may lead to a decrease in braking effect. The countermeasure is to regularly check the wear level of the friction material, and when the wear exceeds a certain limit, replace the brake shoes (or brake pads) in a timely manner. Meanwhile, friction materials with better wear resistance can be used to extend their service life.

Heat problem during braking: During the braking process, a large amount of heat is generated due to the frictional force. If the heat cannot be dissipated in a timely manner, it may affect the braking performance and even damage the braking components. To solve this problem, heat dissipation fins can be designed on the brake disc (or brake drum) or materials with better heat dissipation performance can be used, while ensuring good ventilation conditions around the brake device.

Application scenarios

Ship berthing operation: When the ship docks, the shaft mechanical brake can help the ship accurately control its speed, allowing the ship to dock smoothly at the dock. By applying brakes in a timely manner, operators can adjust the speed and position of the vessel's docking.

Emergency parking situation: When the ship encounters an emergency situation, such as obstacles ahead or malfunctions in the ship's system, the mechanical brake of the shaft system can quickly brake the shaft system, causing the ship to stop as soon as possible and avoiding accidents.