0R-2236 Fuel Injection Pump – Precision-Matched For Caterpillar 3412 Continuous-Duty & Gen-Set Applications

Every fuel injection pump leaves a characteristic pressure trajectory-a unique "fingerprint" that defines how it interacts with the engine's torsional dynamics and combustion stability. The 0R-2236 (Caterpillar OEN) is specifically calibrated for applications demanding unwavering fuel delivery under constant electrical or hydraulic loads, where even a 2% deviation in injected volume per cycle can translate into measurable frequency drift or voltage sag. Unlike its siblings (10R-1001 and 201-4202), which emphasize peak torque or transient response, the 0R-2236 prioritizes isochronous delivery linearity across the entire operating band from 1,200 to 2,200 rpm-making it the preferred choice for prime-power gen-sets and continuous-duty industrial drives.

The 0R-2236 shares the same 10.0 mm plunger diameter and 8.5 mm effective stroke as all 3412 pumps, but critical internal dimensions differ to achieve its flat delivery profile:

Parameter	0R-2236	201-4202 (torque-rise)	10R-1001 (standard)
Control rack travel	14.0 mm (same as 10R-1001)	16.5 mm	14.0 mm
Delivery valve opening pressure	30 MPa ±0.5	28 MPa	25 MPa
Spill port helix angle	22° (shallow)	26°	24°
Governor spring rate	3.2 N/mm (stiffer)	2.8 N/mm	3.0 N/mm
Max delivery @ 1,800 rpm	410 mm³/stroke	310 mm³ (at 1,800, but higher at 1,400)	380 mm³

The higher delivery valve opening pressure (30 MPa) ensures that the injection line pressure wave reaches the injector nozzle faster at low speeds, while the stiffer governor spring reduces droop-providing a nearly horizontal speed-load curve (droop <3% when adjusted). The shallow spill helix produces a slower fuel cut-off, which smooths the torque delivery and reduces cyclic combustion noise.

Bench tests on a calibrated EPS 200 stand (fuel at 40°C, ISO 4113) reveal the 0R-2236's hallmark: a plateau of delivery between 1,400 and 2,000 rpm, where the volume stays within ±2% of 400 mm³/stroke. This is achieved by a specific interaction between the rack position and the spill timing-the spill port begins to uncover only when the rack exceeds 12 mm, meaning that for normal load ranges (rack 8–11 mm), the effective stroke remains nearly constant.

The 0R-2236 is the factory-recommended pump for:

Standby and prime gen-sets (Caterpillar 3412-powered, 50/60 Hz) where frequency stability is paramount.

Gas compression stations driving reciprocating compressors with constant torque demand.

Marine auxiliary generators and bow thruster power packs that operate at near-fixed rpm for extended hours.

It is not recommended for variable-speed propulsion (e.g., marine main engines) or off-highway haul trucks-those applications benefit from the 201-4202's torque-rise profile. The 0R-2236's flat curve would cause sluggish acceleration under changing loads in those scenarios. Always cross-reference the engine serial number and application code to confirm suitability; our team can verify using the Cat SIS database.

Our 0R-2236 remanufactured pumps undergo a specialized process to maintain the delicate spill-port helix geometry:

Chemical stripping of carbon deposits using a non-abrasive bath that does not alter the helix edges.

Air-gauging of the plunger-barrel clearance to 0.003–0.004 mm (Grade A) – any wear exceeding 0.008 mm triggers a full replacement of both parts.

Delivery valve lapping with diamond paste to achieve the precise 30 MPa opening pressure; we verify this with a high-resolution pressure transducer.

Governor dynamic calibration – we simulate a full load-rejection test using an electric dynamometer, recording the droop and isochronous stability. Each unit comes with a 5-point calibration certificate showing actual delivery at 1,200, 1,500, 1,800, 2,000, and 2,200 rpm, with deviations from nominal listed.

All seals are upgraded to Viton® FKM to withstand biodiesel blends (up to B20) and high temperatures. The pump is then run-in for 45 minutes at 1,800 rpm to settle the springs before final inspection.

Q1: Can the 0R-2236 be used on a 3412 engine originally equipped with a 10R-1001 without any modifications?
Physically yes, but the fuel delivery calibration is different-the 0R-2236 will deliver slightly less fuel at full rack, potentially reducing maximum power by ~5%. You may need to adjust the full-load stop screw to compensate, but we recommend consulting the engine's performance spec to ensure the application's power requirements are met.

Q2: How does the higher delivery valve opening pressure affect injector operation?
The 30 MPa opening pressure causes a faster pressure rise in the injection line, advancing the actual start of injection by approximately 0.2 ms at 1,500 rpm compared to the 10R-1001. This may improve combustion efficiency but could increase mechanical noise; we suggest checking the injector nozzle opening pressure-they should be matched.

Q3: What is the recommended fuel filtration level for this pump to achieve maximum service life?
We recommend a primary filter of 10 µm and a secondary of 5 µm (absolute). The plunger-barrel clearance is tight; particles larger than 5 µm can score the surfaces, reducing volumetric efficiency. Use a fuel/water separator upstream as well.

Q4: Is it possible to convert the 0R-2236 from isochronous to droop operation?
Yes-the governor housing has an external droop adjustment screw. Turning it clockwise increases droop (up to 8%). However, we advise doing this only on a test bench to verify the resulting speed-load characteristic, as field adjustments are often imprecise.

Q5: Does the pump come with a new drive gear, or do we reuse the old one?
The pump is supplied without the drive gear-you must transfer the existing gear from your old pump, ensuring the key and retaining bolt are in good condition. We recommend replacing the retaining bolt with a new one (Cat part 8M-3689) and torquing to 120 N·m with Loctite 242.

Q6: How can I verify that the remanufactured pump has not been altered to reduce fuel economy?
Our calibration certificate lists the exact delivery at five speeds. You can cross-check these values against the OEM specification (available in our technical library). Additionally, we seal the calibration screw with a tamper-evident paint; if broken, the warranty is voided.

 

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