Auxiliary Hydraulics and Flow Rates: What Powers Your Attachments
Breakers, augers, tilt buckets and grapples all run off the auxiliary circuit. Flow and pressure decide which attachments work well and which will disappoint.
Every hydraulic attachment is a motor or a cylinder waiting for oil. The excavator's auxiliary circuit supplies it, and two numbers describe what that circuit can do.
Flow and pressure
- Flow (litres per minute) is how fast oil arrives. It sets the speed of an auger, the blows per minute of a breaker and how quickly a grapple closes.
- Pressure (bar or MPa) is how hard the oil pushes. It sets the torque of an auger and the impact energy of a breaker.
An attachment is rated for a flow range. Too little flow and it runs slowly or stalls; too much and it overheats or over-speeds. Pressure must simply be at or above the attachment's requirement.
Where the numbers come from
Rippa's 1 to 2 tonne excavators use a single gear pump feeding the boom, dipper, bucket, swing and auxiliary functions. Full-size skid steers such as the RS10 and RS20 run a four-pump system, quoted at 63.8 + 63.8 + 32.8 + 46.2 L/min, which is why they can drive a trencher or brush cutter that would bog down a smaller machine.
Matching attachments to the circuit
| Attachment | Needs | Notes |
|---|---|---|
| Hydraulic breaker | Moderate flow, steady pressure | Blow rate drops off quickly if flow is short; buy the breaker sized for your model |
| Auger / drilling rig | Flow for speed, pressure for torque | Torque matters more than speed in Hills gravel and limestone |
| Tilt bucket | Low flow | Works well even on 1 tonne machines |
| Hydraulic thumb | Low flow | Uses the same circuit as a tilt bucket |
| Rotating grapple | Two functions | Needs the rotate circuit as well as open/close |
| Skid steer brush cutter, trencher | High flow | Best on RS10/RS20; check RS06/RS07 ratings |
This is why Rippa attachments are sold per model rather than as one-size-fits-all: the R15 breaker is built for the R15 circuit, and the R32 breaker for the R32 circuit.
Single-acting vs double-acting
A breaker only needs oil one way, with a return line to tank. A tilt bucket, thumb or grapple needs oil both ways. Rippa's R-series machines with quick hitch and auxiliary lines are plumbed double-acting, so both kinds of attachment work. If you add a rotating grapple you need a second circuit for rotation; confirm the fitment when you order.
Keeping the circuit healthy
- Keep couplers capped; a spoonful of Perth sand in the oil will score a pump.
- Use the correct hydraulic oil grade for summer temperatures. The main site's hot weather care guide covers it.
- Change the return filter at the first service and on the schedule after that.
See which attachments are listed for each machine in the attachment categories.