Questions about hydraulic couplings

There is no such function; it’s overloaded, and the motor has its own protection mechanism – the motor shuts down as a result of overload interlock.

Yes, based on the working principle of the hydraulic coupling, the prime mover drives the impeller inside the hydraulic coupling; the liquid pumped by this impeller then drives the driven turbine, thereby enabling torque transmission. Load adjustment is carried out using a control valve. As a result, when the equipment being driven gets stuck and cannot rotate for various reasons, the prime mover is not subjected to excessive load that could cause damage.

If the pump or fan seizes due to various reasons, it will not cause the motor to overload; it will only lead to overheating of the working oil.

Hydraulic couplings do not have such a function; the main reason for using them is to achieve soft starting of the prime mover and stepless speed variation of the working machine. When overloaded and the main motor stops, the driven components also stop; however, the motor continues to run while the driven components have stopped, and this is achieved through speed control.

Depending on their application, hydraulic couplings are divided into torque-limiting hydraulic couplings and speed-regulating hydraulic couplings. Among them, the torque-limiting hydraulic coupling is mainly used for starting protection of motor reducers as well as impact protection during operation, along with position compensation and energy buffering ； The speed-regulating hydraulic coupling is mainly used to adjust the input-output speed ratio; its other functions are basically the same as those of the torque-limiting hydraulic coupling. What the original poster is referring to is likely a torque-limiting hydraulic coupling. Such couplings do indeed have the function of protecting the motor: when the load on the driven machine is high or there is a sudden stop, the motor drives the half-turbine to rotate, causing the oil temperature inside the coupling to rise rapidly; this leads to the melting of the fuse plug, and the transmission oil in the coupling is released, causing the motor to run idle, thereby providing protection.

The explanation upstairs was very professional; thanks to the person who posted it

I have a question: When the oil cooler for the variable-speed hydraulic coupler is placed above it, there is significant vibration in the pipeline that carries the working oil to the coupler, and a large amount of gas is present. During subsequent modifications, the position of the cooler was changed to below the hydraulic coupler. Now, the motor experiences overload when started; there is no problem with the motor itself. It is initially suspected that the amount of oil inside the coupler is insufficient, but why would insufficient oil cause the motor to overload?

Motor overload during startup indicates that there is too much oil in the hydraulic coupling, rather than too little; ideally, there should be no oil at all. At startup, the spoon tube must be in the farthest position to empty the oil.

During startup, the load should be increased gradually (the opening of the spoon tube is generally around 25% at startup).

There is no such function as you mentioned; motors generally have their own overload protection. The hydraulic coupler mainly serves to facilitate startup and connection