EDGE AS. 3144659 - Caterpillar

Release Procedure
Personal injury can result from hydraulic oil pressure and hot oil.Hydraulic oil pressure can remain in the hydraulic system after the engine has been stopped. Serious injury can be caused if this pressure is not released before any service is done on the hydraulic system.Make sure all of the attachments have been lowered, oil is cool before removing any components or lines. Remove the oil filler cap only when the engine is stopped, and the filler cap is cool enough to touch with your bare hand.
Shut off the engine.
Apply the parking brake.
Slowly loosen the filler cap in order to release the pressure.
Tighten the filler cap.
The pressure in the hydraulic system has been released. Lines and components can be released.