Quick Coupler
A quick coupler is a connection with check valves on both halves that lets hydraulic lines be disconnected and joined without tools during attachment changes. When separated, each side closes off within itself and no oil is spilled. Residual pressure left in the line can make reconnection impossible.
The most frequently encountered problem is residual pressure. If the attachment sits in the sun and heats up, or if the line is disconnected under pressure, the check valves inside the female and male halves cannot open against the pressure. The solution is to relieve the line to tank by moving the lever back and forth a few times after the system is shut down; many machines have a separate pressure relief arrangement for this.
- Flat face type: no oil remains on the face when separated and it does not hold dirt; preferred in jobs where attachments are changed often.
- Pressure drop: the coupler narrows the internal passage; if an undersized fitting is chosen the line heats up and motion slows down.
- Dust cap: the cap must be fitted while disconnected; the coupler face is the system's most exposed contamination entry point.
On machines where attachments are changed, if electronic lever control is being used, it is a good habit to use the Emergency Stop so that the relevant lever cannot be commanded after the attachment is removed.
Where this term is used: What Is a Hydraulic Lever Retrofit Kit? Definition, Components, Operating Principle