Description
The T38 / T45 Shank Adapter (L550mm) is a precision-engineered interface component designed exclusively for the Tamrock HL500 hydraulic drifter (manufactured under the Sandvik brand). Positioned between the drifter’s piston and the drill string, the shank adapter performs two simultaneous, mechanically demanding functions: transmitting high-frequency impact energy axially into the drill rod, and transferring rotation torque through the spline coupling without slip or vibration loss.
Dimensional accuracy is paramount. The HL500’s piston strikes at frequencies exceeding 2,000 blows per minute; any geometric deviation in the shank’s spline bore or thread profile concentrates stress, accelerates wear, and ultimately damages the drifter’s rotation chuck — a repair cost many times greater than the shank itself.
RockHound’s HL500 shank adapters are CNC-machined and heat-treated to exact Sandvik OEM tolerances, making them fully interchangeable with original equipment while delivering extended service intervals.
Material — 23CrNiMo Alloy Steel
All RockHound shank adapters are produced from 23CrNiMo low-alloy case-hardening steel, selected for its exceptional combination of surface hardness, core toughness, and impact fatigue resistance — the three properties that define shank adapter longevity in hydraulic drifter applications.
Why 23CrNiMo outperforms standard tool steels:
- Chromium (Cr): Increases hardenability and oxidation resistance at elevated surface temperatures generated by high-frequency impacts.
- Nickel (Ni): Preserves core ductility after deep carburizing, preventing brittle fracture under shock loading.
- Molybdenum (Mo): Refines grain structure, resists temper embrittlement, and maintains hardness at the carburized case depth.
The result is a shank that withstands tens of millions of piston blows without premature fatigue cracking — a failure mode common in lower-grade alternatives.
Further reading: Rock Drill Rod Material Comparison: 23CrNiMo vs Sanbar64
Key Features
20-Hour Carburizing Heat Treatment
Every shank adapter undergoes a proprietary 20-hour gas carburizing cycle followed by controlled quenching and low-temperature tempering. This extended cycle achieves:
- Case depth: Sufficient to maintain hardness well below the contact surfaces under progressive wear.
- Surface hardness: 58–62 HRC — hard enough to resist abrasive spline wear and thread galling.
- Core hardness: 38–42 HRC — tough enough to absorb the bending and tension stresses of each impact cycle without cracking.
Standard industry heat treatments (8–12 hours) produce shallower case depths that wear through rapidly in heavy-duty HL500 applications.
Technical reference:20-Hour Heat Treatment in Rock Drilling Tools
1. Precision 10-Spline Drive (Ø58.8mm)
The drive end features 10 high-precision external splines machined to a nominal diameter of Ø58.8mm, matching the HL500 rotation chuck’s internal geometry. Tight spline tolerances ensure full contact across all flanks, distributing torque evenly, reducing point loading, and minimising rotational backlash that would otherwise accelerate chuck wear.
2.CNC-Ground Thread Profile
Both T38 and T45 male threads are finish-ground (not just turned) to guarantee flank angle accuracy and root radius consistency. Correct thread geometry is critical for efficient energy transfer: a poorly formed thread reflects impact energy back into the drifter instead of propagating it down the drill string.
3.Integrated Flushing Bore
A precision-drilled central water/air passage runs the full 550mm length, maintaining the unobstructed bore diameter required for effective cuttings flushing and bit cooling in deep-hole applications.
4.OEM Logo Marking Support
Available with laser engraving or steel stamping of your distributor logo (max. 100 × 100mm), providing durable brand visibility even after extended field use.
Process overview: Rock Drill Shank Adapter Production Process
Specification
| Parameter | T38 Model | T45 Model |
|---|---|---|
| Compatible Drifter | Tamrock HL500 (Sandvik) | Tamrock HL500 (Sandvik) |
| Part Number | 428-4555-9176 | 428-4555-9177 |
| Thread Type | T38 | T45 |
| Total Length (L) | 550 mm | 550 mm |
| Shank Diameter (D) | 45 mm | 45 mm |
| Spline Count | 10 | 10 |
| Spline Diameter | Ø58.8 mm | Ø58.8 mm |
| Material | 23CrNiMo Alloy Steel | 23CrNiMo Alloy Steel |
| Surface Hardness | 58–62 HRC | 58–62 HRC |
| Weight | 5.3 kg | 6.0 kg |
| Heat Treatment | 20-hr Carburizing | 20-hr Carburizing |
| Flushing | Central water/air bore | Central water/air bore |
Applications
These shank adapters are engineered for high-productivity drilling in demanding environments:
- Underground Development & Tunneling: Long drifting rounds in hard rock requiring consistent energy transfer and minimal vibration-induced alignment drift.
- Open-Pit Bench Drilling: High-volume production blasting where shank service life directly impacts cost-per-metre.
- Long-Hole Stoping (Underground Mining): Uphole and downhole production drilling where precise thread engagement prevents string decoupling at depth.
- Quarrying: Dimension stone and aggregate operations using Sandvik/Tamrock HL500-equipped drill rigs.
Compatible drilling rigs include all Sandvik and Tamrock top-hammer platforms equipped with the HL500 hydraulic drifter, including jumbo drill and sinker drill configurations.
How to Select the Right Shank Adapter
Selecting an incorrect shank adapter causes accelerated piston wear, energy loss, and potential drifter failure. Verify the following four parameters before ordering:
Step 1 — Confirm Your Drifter Model Check your rig’s documentation or drifter nameplate for the model designation. The HL500’s spline bore (Ø58.8mm, 10-spline) is specific to this drifter family; it is not interchangeable with HL500L, HL600, or other Sandvik drifter series.
Step 2 — Match the Thread Type to Your Drill String
- T38: Standard for medium-diameter holes (Ø48–64mm). Higher energy efficiency in shorter drill strings. Best for development drives and tunnelling.
T45: Higher thread rigidity and larger cross-section for Ø64–89mm holes. Recommended for bench drilling and applications with longer drill string assemblies where torsional stiffness matters.
Step 3 — Verify the Shank Length The 550mm length is the OEM-specified dimension for the HL500. Using a non-standard length alters the piston-to-shank contact point and can misalign the flushing tube connection, causing overheating or poor cuttings evacuation.
Step 4 — Assess Operating Conditions In highly abrasive formations (quartzite, granite), prioritise inspecting the spline drive end more frequently. In corrosive underground environments (acid mine drainage), confirm that thread grease is applied at every rod change.
Selection guide: Shank Adapter: Function, Work, Choose & Maintenance
Maintenance Guidelines
Correct maintenance practice extends shank adapter service life by 30–50% and protects the drifter from secondary damage.
Thread Lubrication
Apply high-quality, copper-based or molybdenum-disulfide thread grease to both the male thread and the rod coupling at every connection. Dry-running threads gall rapidly under the combination of torque and axial vibration.
Flushing Bore Integrity
Verify that the central bore is unobstructed before each shift. A blocked flushing passage reduces bit cooling efficiency and allows cuttings to pack around the bit, increasing penetration resistance and impact load on the shank.
Shank Shoulder Condition
The shank shoulder (piston impact face) should be flat and free of impact craters. Shoulder peening beyond 1mm depth indicates piston alignment issues that must be diagnosed at the drifter level — continued drilling accelerates catastrophic failure.
Storage
Store shank adapters horizontally on padded racks, protected from moisture. Apply a light preservative oil to thread and spline surfaces before storage periods exceeding two weeks.
Spline Inspection
Inspect spline flanks at each shift change. Acceptable wear: slight polishing of flank surfaces. Replace immediately when:
- Visible rounding or deformation of spline tooth edges is present.
- Lateral play (backlash) in the rotation chuck exceeds 1.5mm.
- Spline root shows cracking or pitting.
Continued use of a spline-worn shank transfers uneven impact loading to the rotation chuck, causing expensive drifter rebuilds.
Related Production
| Threaded Button Bits | Drill Rods | Coupling Sleeves |
|---|---|---|
|
T38 Threaded Button Bits: • T38 Thread Button Bit | T38 Retract Bit 64-70mm • T38-76mm Thread Button Bit For Bench Drilling • T38-76mm Retrac Button Bits For Bench Drilling T45 Threaded Button Bits: • T45 Retract Bit | T45 Thread Button Bit For Sale |
T38 Drill Rods: • T38 Extension Rod for Top Hammer Drilling • T38 MF Rod For Top Hammer Drilling • T38 Guide Rod | T38 Guide Tube For Top Hammer • T38-H35-T38 MF Drill Rod for Drifting & Tunneling T45 Drill Rods: • T45 Extension Round Rod For Long-Hole Drilling • T45-46mm Speed MF Rod For Long-Hole Drilling |
T38 Coupling Sleeve: • T38 Coupling Sleeve For Top Hammer Drilling T45 Coupling Sleeve: • T45 Coupling Sleeves For Top Hammer Drilling |
FAQ
Yes. RockHound's T38 and T45 shank adapters are manufactured to exact OEM dimensional specifications and are fully interchangeable with Sandvik part numbers 428-4555-9176 (T38) and 428-4555-9177 (T45). All critical dimensions — including spline geometry, thread profile, shank length, and flushing bore diameter — are verified against original Sandvik engineering drawings before production approval.
Both fit the same HL500 drifter spline bore, but they differ in thread size and application. The T38 thread has a smaller cross-section suited to drill strings targeting Ø48–64mm hole diameters, offering efficient energy transfer in medium-depth development drilling. The T45 thread has a larger, more rigid cross-section designed for Ø64–89mm holes and longer drill strings, providing greater torsional stiffness in bench and production drilling where string weight is higher. Choosing the wrong thread for your hole size increases energy loss and premature thread wear.
Replace the shank adapter when any of the following conditions are observed:
- Thread flank thinning exceeds 25% of the original profile;
- Spline tooth edges show visible rounding or plastic deformation;
- The piston impact shoulder has peened beyond 1mm depth;
- Penetration rate drops unexpectedly on a known formation — often an indicator of energy loss through a damaged shank.
Continued use past these thresholds transfers damage to the drifter piston and rotation chuck, resulting in repair costs significantly exceeding the cost of a replacement shank.
No. The Ø58.8mm, 10-spline configuration is specific to the HL500. Other Sandvik drifters — including the HL600 and HL700 — use different spline diameters and counts. Installing a mismatched shank will damage the drifter's rotation chuck immediately upon operation. Always verify the drifter model before ordering.
550mm is the Sandvik OEM-specified length for the HL500. Deviating from this length alters the piston strike geometry and flushing tube alignment. However, for verified rig modifications requiring a non-standard length, our technical team can evaluate custom production requests. Please submit your engineering drawings and rig specifications for assessment.