| Parameter | Specification |
|---|---|
| Product Name | Speed Sensor / RPM Revolution Sensor |
| COGENG Part Number | 125-2966 (1252966) |
| OEM Equivalent | Caterpillar 125-2966, 1252966 |
| Product Type | Magnetic Pickup / Inductive Speed Sensor |
| Sensor Type | Variable reluctance (magnetic) |
| Output Signal | AC voltage (frequency proportional to engine speed) |
| Application | Engine RPM monitoring / Crankshaft position |
| Compatible Models | Caterpillar 320C, E312C Excavators |
| Material | Iron + Rubber (seals: NBR) |
| Packing | PP bag inside, carton box outside |
| Place of Origin | Guangdong, China |
| Brand Name | COGENG |
| Certification | ISO9001 |
| Supply Capacity | 500 PCS |
| Brand | Part Number |
|---|---|
| COGENG | 125-2966, 1252966 |
| Caterpillar | 125-2966, 1252966 |
| Interchange | 125-2965, 125-2967, 125-2968, 125-2969 |
| Model | Series | Engine | Application |
|---|---|---|---|
| 320C | C-Series | CAT 3066 / C6.4 | Speed / RPM sensor |
| 320C L | C-Series | CAT 3066 / C6.4 | Speed / RPM sensor |
| 320C LU | C-Series | CAT 3066 / C6.4 | Speed / RPM sensor |
| 320C U | C-Series | CAT 3066 / C6.4 | Speed / RPM sensor |
| Model | Series | Engine | Application |
|---|---|---|---|
| E312C | C-Series | CAT 3054 / 3114 | Speed / RPM sensor |
| E312C L | C-Series | CAT 3054 / 3114 | Speed / RPM sensor |
| Model | Series | Compatibility |
|---|---|---|
| 320B | B-Series | Verify fitment |
| 322C | C-Series | Verify fitment |
| 325C | C-Series | Verify fitment |
| 330C | C-Series | Verify fitment |
Note: Verify compatibility with your equipment model, engine serial number, and production year before ordering. Contact COGENG with your machine details for exact application verification.
| Component | Function |
|---|---|
| Sensor Type | Variable reluctance (magnetic pickup) |
| Target | Flywheel ring gear teeth or crankshaft tone wheel |
| Output | AC voltage sine wave (frequency = engine RPM × number of teeth) |
| ECU Use | Engine speed calculation, fuel injection timing, protection |
| Engine Speed (RPM) | Output Voltage (AC) | Frequency (Hz) |
|---|---|---|
| Cranking (200 RPM) | 0.5 - 1.5 V | Low frequency |
| Idle (800 RPM) | 2.0 - 4.0 V | Medium frequency |
| Working (1,500 RPM) | 4.0 - 8.0 V | Higher frequency |
| Rated (2,200 RPM) | 6.0 - 12.0 V | High frequency |
| Function | Description |
|---|---|
| Engine RPM Display | Provides signal to tachometer (dash display) |
| Fuel Injection Timing | ECU uses speed signal for timing calculation |
| Engine Protection | Over-speed detection and derate |
| Starting Control | Starting motor disengagement signal |
| Diagnostics | Speed sensor fault detection (DTC) |
| Parameter | Specification |
|---|---|
| Sensor Type | Variable reluctance (magnetic pickup) |
| Output Signal | AC voltage (sine wave) |
| Output Voltage (min) | 1.0 V AC @ 200 RPM |
| Output Voltage (typical) | 2-12 V AC (engine speed dependent) |
| Coil Resistance | 200 - 500 Ω @ 20°C |
| Inductance | 100 - 300 mH |
| Air Gap | 0.5 - 1.5 mm (0.020 - 0.060 in) |
| Connector Type | 2-pin Deutsch / AMP |
| Parameter | Specification |
|---|---|
| Housing Material | Zinc-plated steel / Stainless steel |
| Thread Size | M14 × 1.5 |
| Hex Size | 17 mm (11/16") or 19 mm (3/4") |
| Seal Material | NBR (oil resistant) |
| Weight | 0.06 - 0.10 kg (0.13 - 0.22 lbs) |
| Overall Length | 50-70 mm |
| Tip Material | Magnetic steel |
| Pin | Function | Signal Type |
|---|---|---|
| Pin 1 | Signal (+) | AC voltage (variable frequency) |
| Pin 2 | Signal (-) / Shield | Ground / Shield |
| Warning | Detail |
|---|---|
| Engine hazard | Engine may start unexpectedly during testing. Keep clear of fan, belts, pulleys. |
| Hot surfaces | Allow engine to cool before touching. |
| Electrical | Disconnect battery before working on electrical system. |
| Flying debris | Wear safety glasses. |
| Moving parts | Keep hands clear of flywheel area. |
| Air gap | Incorrect air gap can cause sensor damage or no signal. |
✔ OEM Replace Number: 125-2966, direct fit for Caterpillar excavators and 3116/3126 engines
✔ Precision Magnetic Pickup: Accurate engine RPM signal for optimal performance and diagnostics
✔ Wide Compatibility: Works with CAT 320C, 325C, 330C, E312C, E320C, plus Freightliner trucks with 3116/3126 engines
✔ Heavy Duty Construction: Heat and vibration resistant for demanding construction environments
✔ Plug & Play Installation: Direct replacement, no modification required
✔ Cost Effective: OEM quality at competitive price
Frequently Asked Questions
Q: What Caterpillar models use the 125-2966 revolution speed sensor?
A: The COGENG 125-2966 revolution speed sensor is a direct OEM replacement specifically designed for Caterpillar 320C and E312C excavator models. It may also be compatible with other Cat equipment where this sensor part number is specified. This sensor monitors engine rotational speed and provides critical RPM data to the engine ECM. Always verify this part number against your machine's parts manual or the original sensor's identification markings to confirm exact compatibility before ordering.
Q: What are the symptoms of a failing revolution speed sensor on a Cat 320C or E312C?
A: Common symptoms include engine stalling or failure to start, intermittent engine shutdowns, erratic or incorrect RPM readings on the monitor panel, rough running or misfiring, active diagnostic trouble codes related to the speed sensor circuit, the engine entering a derate or limp mode, or loss of throttle response. A faulty speed sensor can cause significant engine performance issues and should be replaced promptly to avoid potential engine damage.
Q: How does the revolution speed sensor affect engine operation?
A: The revolution speed sensor continuously monitors engine rotational speed (RPM) and transmits real-time data to the engine ECM. This critical information is used to control fuel injection timing, fuel delivery quantity, and engine protection functions. Without accurate RPM data, the engine ECM cannot properly manage combustion or protect the engine from overspeed or underspeed conditions.
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