We get asked about this a lot, so we decided to make a brief "How To" video on the subject of mini excavator auxiliary hydraulics circuits.
It's crucial to select the correct circuit for the type of attachment you want to power.

• Single-Acting for breakers, hammers, flails, mulchers. This is because they cannot have any back pressure and also may only be designed to run 1 way.
  
• Double-Acting for grabs, tree shears, augers (it's useful to be able to reverse the flight), hydraulic tilt-ditchers and grading beams, which need 2 way circuits.

Every make and model of mini excavator will be slightly different. For example, on larger machines, the valve may be in the offside (operator's right) engine compartment. On some Cat minis, there's a panel by the step into the cab. However, all of them use some sort of 90 degree throw to switch between single-acting and double-acting.

If at all possible, refer to the operator's manual for your mini excavator.