YT28 vs YT29A Air-Leg Rock Drill: Hole Size, Air Demand, and Selection

Quick answer: for the current PerfoMax reference configurations, the YT28 is the more conservative starting point when your drilling pattern stays within 34–42 mm and plant air is a constraint, while the YT29A extends the reference hole range to 34–45 mm and carries a higher reference air demand. Both current product pages use an H22 × 108 mm shank reference, but that does not make every rod, bit, taper, air leg, hose, oiler, or supplier revision automatically interchangeable.

The selection problem is therefore not “Which model is stronger?” It is: Which quoted configuration matches the hole diameter, available pressure and airflow at the drill, drill-string interface, and approved air-leg setup? This guide is written for mines, tunneling contractors, quarry operators, distributors, and industrial buyers comparing YT28 and YT29A before an RFQ or replacement order.

Important: the figures below are reference values currently published on PerfoMax product pages. Final procurement should be controlled by the supplier datasheet, test pressure, approved air-leg combination, and exact quotation.

1. YT28 vs YT29A: Quick Comparison

For current PerfoMax product details, see the YT28 air-leg rock drill and YT29A air-leg rock drill pages.

2. First Rule: Never Compare Catalog Numbers Without the Test Condition

One of the easiest procurement mistakes is putting two specification sheets side by side and assuming every airflow or impact-frequency figure was measured under the same pressure. Public manufacturer tables show why this is unsafe.

For example, Shenglida publishes a YT-series table with YT28 at ≤81 L/s and ≥37 Hz and YT29A at ≤88 L/s and ≥39 Hz across a stated 0.4–0.63 MPa operating range. A separate Peakroc comparison explicitly states a 0.5 MPa test condition and lists lower reference air-consumption and frequency figures for the same model names. The useful lesson is not that one table is “right” and another is “wrong”; it is that model name alone is not a complete test condition.

Before deciding that one machine consumes less air or drills faster, confirm:

• test or working pressure used for the published figure;
• where pressure is measured—compressor outlet, manifold, or at the drill;
• hose length and internal diameter;
• oiler, valves, fittings, and pressure losses;
• bit diameter, rock condition, and drill-string configuration;
• air-leg feed condition and water injection setup.

Do not convert a catalog L/s value directly into a compressor purchase specification unless the supplier has confirmed the operating pressure, simultaneous loads, distribution losses, and required reserve margin.

3. Hole Diameter: 42 mm vs 45 mm Is a Boundary, Not the Whole Decision

The current PerfoMax reference range is 34–42 mm for YT28 and 34–45 mm for YT29A. That makes the first screening decision straightforward:

• If all planned holes are 34–42 mm: both models may be candidates, so air supply, rock, drilling rate, existing spares, and air-leg configuration become the next filters.
• If the pattern requires 43–45 mm holes: the current YT29A reference range covers that diameter, while the current YT28 reference range does not.
• If the requested diameter sits outside both published ranges: do not stretch the model by assumption; confirm another drill, bit, or drilling method.

Diameter also changes the load on the whole system. A larger bit changes rock contact, cuttings volume, flushing demand, feed behavior, and the energy required to maintain penetration. Therefore, “YT29A reaches 45 mm” should be treated as a compatibility boundary to verify—not a promise that it will always drill a 45 mm hole efficiently under any compressor or rock condition.

4. Air Supply: Why the YT29A Can Be the Wrong Upgrade on an Air-Limited Site

In the current PerfoMax reference data, YT28 air consumption is ≤81 L/s and YT29A is ≤88 L/s. The difference looks modest on paper, but a field system can be sensitive to pressure loss, especially when several pneumatic tools share the same header.

If pressure at the drill falls under load, the buyer may experience reduced impact performance, slower penetration, unstable drilling, or a machine that appears weaker than its catalog. In that situation, buying the nominally higher-output model does not automatically solve the problem. It can simply place more demand on the same restricted air network.

Before changing from YT28 to YT29A, record:

1. compressor rated output and rated pressure;
2. measured pressure at the tool while drilling, not only static pressure;
3. main-line and branch-line sizes;
4. hose length and inside diameter to each drill;
5. number of tools operating simultaneously;
6. condition of couplings, valves, filters, and lubricators;
7. whether water injection creates any additional operating constraint.

The right compressor decision should be made from the complete pneumatic system, not from multiplying one catalog number by the number of drills.

5. Does the YT29A Automatically Drill Faster Than the YT28?

No. The YT29A current reference configuration has a slightly higher impact-frequency figure and a larger reference cylinder diameter, but that does not guarantee a higher field penetration rate in every hole.

Actual drilling rate is affected by rock strength and fracturing, bit type and sharpness, bit diameter, pressure at the drill, air-leg feed, flushing/water condition, rod condition, collaring quality, and operator technique. A correctly supplied YT28 on a 36–40 mm pattern can outperform a poorly supplied YT29A that is starved for air or matched to the wrong bit and feed condition.

For procurement, compare cost per acceptable drilled meter under the same site condition, not only nominal frequency or a supplier’s “more powerful” description.

6. H22 × 108 mm: Same Shank Class Does Not Mean Full Interchangeability

Both current PerfoMax YT28 and YT29A pages identify H22 × 108 mm as the reference shank. That is useful because it narrows the drill-string family, but it is not enough to approve a replacement order.

H22 describes the hexagonal steel size, while the complete drilling connection still depends on the shank end, taper angle, rod length, bit socket, and supplier tolerances. PerfoMax currently lists an H22 × 108 mm rod with an 11° connection option; that product is an example of why the taper must be specified rather than inferred from “H22” alone.

When reusing an existing rod and bit inventory, send the supplier:

• rock-drill model and nameplate photo;
• rod shank size and shank-end dimensions;
• taper angle or verified bit/rod part number;
• bit diameter and bit style;
• rod length;
• photos of the current drill, rod end, and bit socket if drawings are unavailable.

7. Air-Leg Matching Is Part of the Drill Configuration

An air-leg rock drill should not be purchased as an isolated body. The feed leg affects support, feed force, working angle, hose routing, and operator control.

The current PerfoMax YT28 page identifies FT160BC/FT160BD as common pairings. For YT29A, the exact approved air-leg suffix should be confirmed in the quotation instead of being inferred from another supplier’s compatibility table. PerfoMax also lists the FT160-series pneumatic air legs as model-specific equipment where the suffix matters.

For a replacement purchase, do not write only “FT160.” Confirm the exact suffix, mounting interface, working length, hose and control arrangement, and whether the quotation includes the leg, oiler, water accessories, and required connectors.

8. Practical Selection Matrix

9. Six Procurement Mistakes That Create Avoidable Downtime

1. Comparing airflow figures from different pressures. A lower L/s number is meaningless if the test condition is different.
2. Assuming YT29A is always the better drill. A higher-capacity model can be a worse system match when air is constrained or the hole pattern does not need the wider diameter range.
3. Ordering by model name only. Manufacturer, revision, pressure basis, and interfaces must be controlled.
4. Treating H22 × 108 as complete drill-string compatibility. Confirm taper angle, bit socket, rod geometry, and actual part numbers.
5. Ignoring the air-leg suffix. FT160 is a family name; approved pairings and geometry must be verified.
6. Leaving hoses, oiler, and water setup out of the RFQ. The drill body can be correct while the installed system is still wrong.

10. RFQ Checklist: What to Send Before Ordering YT28 or YT29A

A useful RFQ should contain enough information for the supplier to reject a bad match before shipment. Send:

• required hole diameter range and typical hole depth;
• rock type, hardness description, and whether the formation is massive, fractured, or variable;
• number of drills that operate at the same time;
• compressor model, rated output, rated pressure, and measured loaded pressure at the drill if available;
• existing hose ID and approximate hose length;
• required drill model: YT28, YT29A, or supplier to recommend;
• existing air-leg model and exact suffix;
• rod shank, taper angle, rod length, and bit diameter;
• photos of nameplates and interfaces for replacement orders;
• whether the quote must include air leg, oiler, hoses, water accessories, spare parts, and tools;
• required inspection, packing, documentation, and destination details.

If your application is still open, start with the current PerfoMax Rock Drills collection and provide the operating data above so the quoted configuration can be checked as a complete system.

11. FAQs

What is the main difference between YT28 and YT29A?

In the current PerfoMax reference configurations, YT28 covers 34–42 mm holes with ≤81 L/s reference air consumption, while YT29A covers 34–45 mm with ≤88 L/s and a slightly higher reference impact frequency. The practical difference is therefore a combination of hole range and pneumatic-system demand, not simply smaller versus stronger.

Can YT28 and YT29A use the same H22 × 108 drill rods?

Both current product pages specify an H22 × 108 reference shank, so they belong to the same general shank class. However, rod and bit interchangeability still requires confirmation of taper angle, shank-end geometry, bit socket, dimensions, tolerances, and supplier revision.

Why do different YT28 or YT29A catalogs show different air-consumption figures?

Published specifications can use different test pressures and configurations. A public 0.5 MPa comparison, for example, reports different airflow and frequency figures from other tables that state a broader 0.4–0.63 MPa range. Always compare values at equivalent test conditions.

Should I choose YT29A if I want faster drilling?

Not automatically. Field penetration depends on delivered pressure, bit condition and diameter, rock, feed, flushing, rod condition, and operator setup. A well-matched YT28 can be the better production choice on a 34–42 mm pattern with limited air capacity.

What should I measure if the drill loses power when several machines run?

Measure dynamic pressure at the drill while the tools are operating, then check compressor capacity, distribution line size, branch restrictions, hose ID and length, fittings, filters, and lubricators. Static compressor pressure by itself does not show what the drill receives under load.

Technical References

• Shenglida — YT28 Air-Leg Rock Drill / YT Series Technical Table
• Shenglida — YT29A Air-Leg Rock Drill / YT Series Technical Table
• Peakroc — Air-Leg Rock Drill Model Comparison at 0.5 MPa

These external references are used to cross-check model-family conventions and to illustrate why test pressure must accompany air-consumption and frequency figures. PerfoMax-specific product claims in this guide come only from the current PerfoMax product pages.

Get the Configuration Right Before You Order

If your holes are 34–42 mm and your site is air-limited, the YT28 is the logical reference point. If your pattern extends to 43–45 mm, the YT29A is the model to evaluate—but only after confirming that the air system, drill string, taper, air leg, and accessories match the quoted configuration.