Sunfab SCM-012W Hydraulic Motor

Sunfab SCM-012W-H-I41-W25-S3G-100 Bent-Axis Axial Piston Hydraulic Motor

The Sunfab SCM-012W-H-I41-W25-S3G-100 is a bent-axis axial piston hydraulic motor engineered for open and closed hydrostatic transmission loops. Featuring a 40° bent-axis spherical piston design, this motor delivers high starting torque, low mechanical and volumetric losses, and exceptional high-speed stability.

Constructed specifically for harsh duty cycles—including marine deck machinery, offshore winches, mobile cranes, and demanding industrial power packs—the SCM-012 platform utilizes heavy-duty tapered roller bearings engineered to absorb high radial and axial dynamic shaft forces. Equipped with high-pressure hydrogenated nitrile/NBR seals (“H” configuration), this unit maintains casing integrity under elevated continuous working pressures up to 350 bar (5,075 psi) and intermittent peaks up to 400 bar (5,800 psi).

Key Engineering Features

1. Optimized 40° Bent-Axis Spherical Piston Topology: Delivers instantaneous breakaway torque and low friction throughout startup and deceleration phases, preventing low-speed cogging.
2. High Casing & Dynamic Load Rating: Dual tapered roller bearings accept direct drive coupling or pinion/sprocket loads without requiring external outboard bearing support.
3. Reversible Bi-Directional Operation (“W”): Engineered to operate at full pressure ratings across both clockwise and counter-clockwise rotations without internal valve-plate asymmetry.
4. Standardized Metric Interface: Built to ISO 3019-2 standard flange geometry and DIN 5480 spline parameters for drop-in retrofit compatibility.
5. High-Pressure Shaft Sealing: The “H” nitrile sealing package withstands elevated case backpressures, reducing seal blowout risks during thermal spikes and cold starts.

Technical Details

Terminal & Port Allocations

• Port A (Main Work Port – G 3/4″ BSPP): Drives CW shaft rotation when acting as pressurized inlet.
• Port B (Main Work Port – G 3/4″ BSPP): Drives CCW shaft rotation when acting as pressurized inlet.
• Drain Port L / T1 (G 1/2″ BSPP): Case drain line for internal lubricating bypass. Must be routed unconditionally to the reservoir below minimum fluid level.
• Secondary Drain / Flushing Port T2 (G 1/2″ BSPP): Auxiliary purging line used during vertical mounting or loop flushing circuits.

Manufacturer Cross-References

• Direct Drop-in Replacement: Sunfab SCM-012W-N-I41-W25-S3G-100 (Nitrile standard vs. H high-pressure seal pack).
• Equivalent Displacement/Envelope Cross-Reference:
  • Parker Hannifin / Volvo F11 Series: F11-012-MB-SV-K-000 (Check shaft envelope and port thread pitch).
  • Rexroth Bosch: A2FE12 / A2FM12 series (ISO 4-bolt / Spline adaptation required).
  • Bucher Hydraulics / Bondioli & Pavesi: M4-012 equivalent bent-axis frames.

Frequently Asked Questions

What is the primary difference between the SCM ‘H’ and ‘N’ seal options?

The ‘H’ designation identifies a heavy-duty nitrile/HNBR sealing system designed to withstand higher casing backpressures and transient thermal spikes compared to the baseline ‘N’ (standard Nitrile) option. The ‘H’ seal is recommended for installations subject to cold weather starts or variable case drain flow restrictions.

Can the Sunfab SCM-012W be driven as a hydraulic pump?

While mechanically similar to the Sunfab SCP series, the SCM is timed specifically for high starting torque as a motor. If used as a pump, volumetric efficiency and suction performance will drop substantially due to valve plate timing differences. Always install an SCP series unit for primary pump operations.

Does the motor have internal cross-port relief or anti-cavitation valves?

No. The SCM-012W-H-I41-W25-S3G-100 is a bare unit with standard 40° S3 connection covers and no internal valve block. In closed loops, charge pump pressure prevents cavitation; in open circuits driving high-inertia overrunning loads, an external anti-cavitation valve block or counter-balance (overcenter) valve must be installed across ports A and B.

What is the maximum case drain pressure permissible during cold starts?

During peak cold starts (high fluid viscosity), momentary peak case pressure must remain under 4.0 bar. For continuous operation at typical running temperatures, ensure case drain pressure does not exceed 2.5 bar to guarantee rated seal lifespan.