Air-leg feed is not simply “more pressure equals faster drilling.” The feed force must keep the bit engaged while allowing impact, rotation and flushing to work. Too much feed can stall rotation, bend the steel or trap the bit. Too little feed can cause unstable contact, poor energy transfer and difficult collaring. The correct setting depends on the exact drill, leg, steel, bit, hole direction, rock and supply condition.
Do not publish or use a universal feed-pressure number across models. Start with the manufacturer’s approved range, then observe the complete drilling response. Isolate the air supply before inspecting the leg, control or connections.
Read the drilling response, not one gauge
| Pattern | Possible interpretation | Evidence to collect |
|---|---|---|
| Rotation slows as feed increases | Overfeed, bit binding, poor flushing or inadequate air supply | Feed-control position, inlet pressure and cuttings return |
| Drill bounces or loses contact | Underfeed, uneven collar or unstable support | Collar condition, leg angle and operator control |
| Leg extends but will not hold | Leakage, valve/cylinder issue or unsuitable geometry | Extension position, visible leak and load condition |
| Steel bends or rubs at the collar | Misalignment, excess feed or unsuitable steel length | Side-view photo and steel specification |
| Feed changes when another tool starts | Shared air-distribution limitation | Simultaneous demand and tool-inlet readings |
A practical balancing sequence
1. Confirm the equipment combination
Record the drill model and suffix, air-leg model, mounting interface, steel and bit. A leg that attaches physically may still provide unsuitable stroke, geometry or thrust. Verify the combination before adjusting operation around a mismatch.
2. Check supply at the point of use
The drill and leg share a system. Check the hose, branch, couplings and operating pressure at the relevant inlet under the approved condition. A steady upstream gauge does not guarantee stable supply when the drill hammers and the leg moves.
3. Establish a stable collar
Set the leg on secure support, align the drill with the planned hole and begin with controlled contact. If the collar breaks out or the steel deflects, stop and correct the setup rather than increasing feed to force progress.
4. Increase feed only while functions remain stable
Observe impact, rotation, cuttings return, steel behavior and operator control together. The best feed point is not the maximum setting; it is the controlled condition where the bit remains engaged without stalling, excessive bending or loss of flushing.
5. Separate feed faults from drill faults
If the leg slips, leaks or moves inconsistently, troubleshoot the leg circuit. If the leg behaves normally but the drill loses impact or rotation, investigate supply, drill string and drill body. If both degrade together, test the shared air path first.
When a supplier needs to be involved
Escalate when the drill-leg pairing is uncertain, the leg cannot hold under the specified setup, the control response changes after service, or no approved operating information is available. Provide geometry and interface evidence, not only a complaint that feed is “weak.”
RFQ fields
- Rock-drill model and suffix
- Air-leg model, suffix and mounting details
- Hole direction, height and working position
- Drill-steel type, length and bit diameter
- Air hose ID, length, connection and shared tools
- Symptom during collaring and full drilling
- Feed-control position or sequence when the symptom appears
- Side-view photos or video of the complete setup
Review Air-Leg Rock Drills and the wider Rock Drills range. To check a drill-leg package, Request a Quote with the full interface record.
FAQ
Is higher air-leg pressure always better?
No. Excess feed can stall or misalign the drilling system. Use the approved range and judge impact, rotation, flushing and steel behavior together.
Why does feed change when another drill starts?
The shared supply may not maintain pressure and flow under simultaneous demand. Check distribution and dynamic conditions at the point of use.
Can I use any air leg that fits the drill?
No. Mounting, stroke, geometry, control and thrust must match the drill and application. Physical attachment alone is not compatibility proof.