Horizontal or vertical shaft
The first thing to settle is the orientation of the output shaft, and the equipment dictates it:
- Horizontal shaft: generators, motor pumps, construction equipment and industrial machinery.
- Vertical shaft: lawn mowers, lawn tractors and zero-turn mowers, where the blade or transmission is driven directly from under the engine.
The Command PRO model names tell you the configuration at a glance. CH means horizontal shaft, CV vertical shaft. A leading E stands for electronic fuel injection (EFI), and the P prefix or the LP and NG suffixes mean propane or natural gas respectively.
Single-cylinder or V-twin
Horizontal-shaft Command PRO singles cover 3.3–10.4 kW, from the CH245 (177 cc) to the CH440 (429 cc), and weigh 15–33 kg. The V-twins start at 674 cc (CH620, 14.2 kW) and go up to 999 cc (CH1000, 27.6 kW; fuel-injected ECH980, 28.3 kW). A twin has more torque and suits commercial equipment that runs many hours a day. A single is more compact and lighter.
For the small vertical singles (CV173–CV224 and the HD and XTX series), the manufacturer states gross torque instead of power: between 9.2 and 14.9 Nm. Compare these by torque and displacement.
Carburettor or electronic fuel injection (EFI)
On EFI versions (ECH, ECV), fuel is metered electronically according to load and temperature, and you no longer need a choke to start. For the same displacement, power can come out slightly higher: the ECH749 delivers 19.8 kW and the CH742 18.6 kW, both 747 cc. For vertical shafts, the Command PRO 888 platform (888 cc) offers 21.6–25.4 kW, carburetted (CV829, CV832) or fuel-injected (ECV830, ECV834).
Petrol, propane (LPG) or natural gas
Alternative fuel engines are derived from the Command PRO range. They do not suffer from stale petrol, the fuel system needs no laying-up over winter and emissions are lower, which is why you find them on generators and commercial equipment. The trade-off is less power than on petrol. On the same 725 cc engine at 3,600 rpm, the petrol CH740 delivers 18.6 kW, the propane CH740LP 16.4 kW and the natural gas CH740NG 14.5 kW.
- Propane (LPG): the carburetted CH730LP and CH740LP, plus the fuel-injected PCH680, PCH740, PCV680 and PCV740.
- Natural gas: the CH740NG, for stationary applications connected to the gas grid.
- Tri-fuel: the CH395TF, a 277 cc single that runs on petrol, propane or natural gas with a conversion kit.
Emission standards
Most petrol engines in the catalogue list EU Stage V on their datasheet. Some models, for example the CH940, CH980 and CH1000, carry only the US EPA Phase III certification. The datasheets of the propane and natural gas engines also list EPA and CARB certifications. If the equipment is sold in the European Union, ask us to confirm the type approval for the model you choose.
Series for lawn mowers
Besides Command PRO, the range includes the Confidant, 7000, SH, HD and XTX series. The vertical-shaft Confidant twins (ZT730, ZT740, EZT740, EZT750) and the 7000 series (KT720–KT726), rated 14.9–20.1 kW, are for lawn tractors and zero-turn mowers. The HD and XTX singles go on walk-behind mowers, and the SH270 is a 196 cc, 4.8 kW horizontal-shaft single.
Replacing an existing engine
Copy the model, specification number and serial number from the engine label. Shaft diameter and length, chassis mounting points, exhaust position, starting system and charging alternator also matter. With these details we can find a compatible engine or the current equivalent version.
For new equipment, tell us what the machine is, the power and speed it needs, the shaft orientation and the fuel you want, and we will propose the right Rehlko model.
