HomeCummins/OnanCummins/Onan RX 45

Cummins/Onan RX 45 Generator Set

The Cummins/Onan RX 45 is a 45 kW (45 kVA) NG/LP standby generator set powered by a Cummins/Onan QSJ2.4 engine. It is available at 120/240 V and 120/208 V, single-phase, 60 Hz and rated 187.5 A. It holds 12.8 L (3.4 gal) of coolant, with a maximum ambient rating of 40 °C. Starting uses battery rated 550 CCA at 12 V. The set measures 2388×864×1157 mm (94.0×34.0×45.6 in), weighs about 635 kg (1400 lb) and produces 67 dBA at 7 m.

45 kW
Standby
2.4 L
Displacement
2
Document types

How to read your Cummins/Onan serial & model number →

Typical fuel consumption for 45–50 kW Bi-Fuel (NG/LP) generators →

Compare with other 45–50 kW Bi-Fuel (NG/LP) generators →

Specifications

FuelNG/LP
Frequency60.0 Hz
Standby power45 kW
Standby kVA45
ControllerPowerCommand 1.1
AlternatorCA Series (Class H insulation)
Voltage options120/240 V, 120/208 V
Phase1
Rated current187.5 A
Circuit breaker250 A
Battery cranking550 CCA
Battery voltage12 V
Max ambient40 °C
Dimensions (L×W×H)2388×864×1157 mm
Dry weight635 kg
Sound level67.0 dBA @ 7 m

Engine

Cummins/Onan QSJ2.4
Coolant capacity12.8 L
Displacement2.4 L
AspirationNaturally aspirated or turbocharged (varies by generator set model)
Rated speed1800 rpm

Maintenance & consumables

for the Cummins/Onan QSJ2.4
ItemSpecCapacityPart #Interval
Air filter
Fuel filterEvery 500 hours of operation or as needed, whichever comes first500 hr
Oil filterEvery 1000 hours of operation or as needed, whichever comes first1000 hr
BatteryAs needed
Belt
Coolant
Oil500 miles or 6 months, whichever comes first804 hr
Spark plug

Recommended fluids

FluidGradeStandardAmbientCapacityNotes
Coolant50/50 mixturebelow 50°C50°C cooling capability, low coolant level shutdown

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Common questions

What size generator is the Cummins/Onan RX 45?

The Cummins/Onan RX 45 is rated 45 kW standby (45.0 kVA).

What engine does the Cummins/Onan RX 45 use?

The Cummins/Onan RX 45 is powered by the Cummins/Onan QSJ2.4 engine.

What fuel does the Cummins/Onan RX 45 use?

The Cummins/Onan RX 45 runs on NG/LP.

Which alternator is fitted to the Cummins/Onan RX 45?

The Cummins/Onan RX 45 uses a CA Series alternator. Insulation class H.

Parts

13
Part #DescriptionQtySystem
A046N983Preventive Maintenance Kit –Heavy Duty2Air filter Amazon eBay
A046N985Preventive Maintenance Kit (Normal Duty Air Filter)2Air filter Amazon eBay
A046N987Preventive Maintenance Kit (Normal Duty Air Filter)2Air filter Amazon eBay
CA115-T12Large, Oil CoolerOil filter Amazon eBay
CA135-E12Large, Oil CoolerOil filter Amazon eBay
A046J612Base Barrier – Elevated Genset1Service part / kit Amazon eBay
A046L270Instruction Sheet1Service part / kit Amazon eBay
CA115-H14SmallService part / kit Amazon eBay
CA115-J12SmallService part / kit Amazon eBay
CA115-L14SmallService part / kit Amazon eBay
CA115-M12LargeService part / kit Amazon eBay
CA115-P12LargeService part / kit Amazon eBay
CA115-R12LargeService part / kit Amazon eBay

Service, wear & replacement parts referenced for this model and its engine — confirm the exact part for your serial number. See the full parts catalog to search and cross-reference.

Fuel consumption

RatingLoadL/hgal/h
Full100%30.288.0
Prime25%14.23.75
Standby25%34.49.09

Available documents

Spec sheet (Cummins/Onan)Spec sheet — NAS-5792-EN (Cummins/Onan)Reference (Cummins/Onan)