HELAC ALTERNATIVE
Atlas 3128312645 Replacement Rotary Actuator
Recorded Helac reference code HP125-S-RF-360-S1-C-H · from HM supply records, to be confirmed against the unit nameplate
Heavy-duty 360-degree alternative rotary actuator for the Atlas Copco / Epiroc part number 3128312645 (also referenced as L3D) used on Boomer face-drill rigs. Our supply records associate this build with the Helac HP125 configuration; the exact tag model code is confirmed from your nameplate before quoting.
Atlas part number
3128312645
Replacement matched to Atlas 3128312645 (also listed as L3D); the supplied build is recorded as Helac HP-series code HP125-S-RF-360-S1-C-H, to be confirmed against the nameplate.
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Independently supplied alternative — not an original Helac or Atlas part. Compatibility is verified before ordering.
Code anatomy
What each part of this code means
Every segment below is read from the manufacturer’s published ordering key. Where a segment is not published, we say so instead of guessing — those are the ones to confirm from the tag or the drawing before ordering.
HP125-S-RF-360-S1-C-H
HP series
| Segment | Field | What it tells you |
|---|---|---|
| HP125 | Series and size | HP series, size 125 — the HP family uses its own key |
| S | Measurement system | Special / custom build (older tags use S for special) — not a standard E or M unit |
| RF | Housing / mounting | Rear flange |
| 360 | Rotation | Standard 360° rotation |
| S1 | Shaft / flanges | Cantilever — shaft flange only (single) |
| C | Valve | Counterbalance valve fitted |
| H | Seals and bearings | Standard seals and bearings |
The HP/HTX families write the size into the series field; the remaining positions follow the same order as the L-series key.
Full ordering key and how to read a tag: identifying a rotary actuator.
What the 360° sweep changes on this build
A full-turn build: the output sweeps a complete revolution. The hose loop and its clamping have to survive the whole sweep, which is why a full-turn unit is checked as a hose-routing question as well as a torque question.
- Check the hose loop clears the housing through the full revolution, not just at the rest position.
- Confirm the duty actually needs a complete turn — a half-turn build of the same size is the usual choice where it does not.
- Rotation stops, if the machine has them, sit outside the actuator and still have to be checked.
When this sweep is the right build
- Duties that genuinely index through a full revolution — rod handling, turret positioning, continuous swing.
- Linkages where the return path is part of the cycle rather than a reversal of the same half turn.
- Machines already built around a full-turn hose loop, where a half-turn unit would leave the routing over-travelled.
Confirming the sweep on the machine
- Turn the linkage through a full revolution by hand and watch the hose loop — a unit that binds at three quarters of a turn is a routing problem, not a torque problem.
- Check whether the machine has an external rotation stop; if it does, the sweep on the tag is not the limit the linkage actually uses.
How the sweep sits in the order code
The sweep is the fifth segment of the code. Going to the half-turn build of the same size changes that segment and the internal stop tube; flange, shaft and valve stay as they are. Where a machine only needs two positions, the half-turn build is the shorter hose route and the smaller envelope.
Where these two builds get mixed up
- A full-turn unit is sometimes quoted where the linkage only swings half a turn, which over-travels the hose loop for no benefit.
- If a full-turn unit will not pass a quarter or half turn under load, the cause is usually hose routing or an external stop, not the actuator.
At a glance
Quick reference
- Reference code (from supply records)
- HP125-S-RF-360-S1-C-H
- Original brand
- Helac
- Type
- Rotary actuator
- Rotation
- 360°
- Weight
- 208 kg
- Original part no.
- 3128312645, L3D
Equipment reference
Known applications
Based on our supply records, the Atlas part 3128312645 / L3D actuator is associated with the following Atlas Boomer face-drilling and development rigs. Confirmation against your machine build plate and actuator tag is recommended.
If your machine is not listed, send the full model and serial number — other builds may use the same actuator.
Confirmed data only
Technical specifications
| Product type | Hydraulic rotary actuator |
|---|---|
| Rotation angle | 360° |
| Unit weight | 208 kg |
| Cross reference | Atlas Copco / Epiroc part 3128312645 (L3D) is matched to a Helac HP-series build (HP125 configuration, 208 kg class) from our supply records. The complete tag model code is not assumed — it is verified against the nameplate and mounting drawing before a replacement is confirmed. |
| Further data | Torque, pressure, port and mounting dimensions are shared with the engineering drawing on request. |
HM alternative model — confirmed on inquiry. Send us your original model number, part number or machine details and we confirm the matching configuration, specifications and compatibility, then quote. The exact ordering code — rotation, output and valve arrangement — is confirmed against your unit and is not published online.
Other models in the Helac HP range
Questions
Frequently asked questions
What does the HP125-S-RF-360-S1-C-H replace?+
Our supply records associate this 360° rotary actuator (208 kg class) with the Helac HP-series build referenced as HP125-S-RF-360-S1-C-H. The exact factory model code is confirmed against the unit's nameplate before order. It is listed by Atlas under part numbers 3128312645, L3D. Our alternative is matched to the same rotation, 208 kg class and mounting interface.
How do I know this fits my machine?+
The same actuator is recorded on the Boomer M2d, Boomer XL3, Boomer 353, Boomer L2c, Boomer L2d. Before quoting we confirm the mounting face, port position and rotation against the tag and a photo of your unit, so the replacement matches your exact build.
Is 3128312645 the heavy rotary actuator on the Boomer M2d and XL3?+
Part number 3128312645 (also referenced as L3D) is the heavy-duty 360-degree rotary actuator recorded on the Atlas Copco / Epiroc Boomer M2d, XL3, 353, L2c and L2d rigs, in the 208 kg class. Our supply records associate it with a Helac HP125 build; the exact tag model code varies by machine configuration and is confirmed from your nameplate and a photo or drawing before ordering, along with the mounting face, port position and rotation.
Why is the exact HM model and price not shown?+
We confirm the HM model per inquiry after verifying the interface and operating parameters with you. This avoids shipping a part that looks right by model name but differs in mounting or rotation. Price is provided with that confirmed quote.
Request a check
Looking for an alternative to this model?
Send us the original model number, part number, machine model or a drawing. We check the available option and confirm specifications and compatibility for you.
- Original model / part number
- Machine brand & model
- Quantity & annual demand
- Mounting photo or drawing (if available)
Or email directly: hm@hmhydraulics.com