Rehlko Command Pro CH680-3012 22.5HP Walker Replacement Engine
The Rehlko Command Pro CH680-3012 is a 22.5 HP, 674cc commercial V-Twin gasoline engine configured for select Walker mower applications. Formerly sold under the Kohler Engines brand, the CH680-3012 uses a Walker-specific flush crankshaft configuration and is a replacement for CH23S-76634 / PA-76634.
If you are replacing a Kohler Command Pro engine in a Walker mower, matching the complete engine specification number is important. The CH680-3012 is not simply a standard CH680 with a different label; its crankshaft and application-specific configuration are designed for compatible Walker equipment.
Replacing CH23S-76634? The Rehlko Command Pro CH680-3012 is the documented replacement for the PA-76634 Walker engine application.
Always verify your existing engine model/specification number and Walker equipment model before ordering. If you are unsure, call Carroll Stream Motor Company at 1-888-208-2088 with your model and serial number.
Rehlko CH680-3012 Key Features
- 22.5 HP Command PRO V-Twin: Commercial horizontal-shaft engine designed for demanding equipment applications.
- 674cc Displacement: Two-cylinder, 4-cycle OHV engine platform with strong low-speed torque.
- Walker-Specific Flush Crankshaft: Specialized crankshaft configuration for compatible Walker mower applications.
- Electric Start: Heavy-duty 12-volt electric starting system.
- 15-Amp Regulated Charging System: Supports the mower's battery and electrical system during operation.
- Full-Pressure Lubrication: Pressurized oil circulation with filtration for commercial-duty operation.
- Forced-Air Cooling: Air-cooled design engineered to manage operating temperatures under load.
- 36.8 ft-lb Peak Torque: Strong torque output for mowing and other demanding equipment loads.
- Mechanical Governor: Helps maintain consistent engine speed as operating loads change.
- Commercial Command PRO Platform: Built around Rehlko's long-running professional V-Twin engine family.
CH680-3012 Specifications
| Rehlko Command Pro CH680-3012 Specifications | |
|---|---|
| Brand | Rehlko |
| Engine Family | Command PRO |
| Model | CH680-3012 |
| Manufacturer Part Number | PA-CH680-3012 |
| Application | Select Walker mower applications |
| Engine Type | 4-Cycle OHV V-Twin |
| Orientation | Horizontal Shaft |
| Displacement | 674cc / 41.1 cu. in. |
| Maximum Power | 22.5 HP |
| Peak Torque | 36.8 ft-lb |
| Bore x Stroke | 3.15 x 2.64 in. (80 x 67 mm) |
| Starting Type | 12-Volt Electric Start |
| Charging System | 15-Amp DC Regulated |
| Governor | Mechanical |
| Fuel | Unleaded Gasoline, 87 Octane Minimum |
| Cooling System | Forced Air / Air-Cooled |
| Lubrication System | Full-Pressure Lubrication With Oil Filter |
| Oil Capacity | Approximately 2.0 US Quarts (1.9 L) |
| Crankshaft Configuration | Walker-Specific Flush Crankshaft / No Standard Shaft Extension |
| Reduction | None |
| Dimensions | Approximately 14 x 17.7 x 19 in. |
| Fuel Tank Included | No |
| Muffler Included | No |
| Air Cleaner Included | No — designed for the applicable equipment's remote air-cleaner system |
| Manufacturer Warranty | 3 Years |
Walker CH23S-76634 Replacement
The Rehlko CH680-3012 replaces the Kohler CH23S-76634 / PA-76634 used in Walker mower applications. The older PA-76634 engine has been superseded by PA-CH680-3012.
This cross-reference is especially important because Walker mower engine installations can use application-specific crankshafts and related components. Two engines with similar horsepower and displacement are not necessarily interchangeable.
What Does "Flush Crankshaft" Mean on the CH680-3012?
The CH680-3012 flush crankshaft refers to its specialized Walker configuration. Unlike many horizontal-shaft engines that have a conventional PTO shaft extending several inches from the crankcase, the CH680-3012 does not use a standard extended output shaft.
This difference is critical when selecting a replacement engine. A standard CH680 with a 1-inch or 1-1/8-inch extended shaft should not be assumed to replace the CH680-3012 simply because the horsepower and engine family are similar.
Designed for Walker Mower Applications
The CH680-3012 is an application-specific version of the Rehlko Command PRO horizontal V-Twin. It is intended for compatible Walker equipment requiring this engine configuration rather than as a universal replacement engine.
When repowering a Walker mower, verify the original engine's complete model and specification number. Matching only "CH680," "22.5 HP," or "674cc" is not enough to guarantee proper fitment.
Why Choose the Rehlko Command PRO CH680?
The CH680 belongs to Rehlko's Command PRO commercial engine family. Its 674cc OHV V-Twin design combines full-pressure lubrication, oil filtration, electric starting, mechanical governing, cast-iron cylinder liners, and commercial-duty construction for equipment expected to operate under sustained loads.
Rehlko is the current name of the engine business formerly known as Kohler Engines. Because of the brand transition, you may see this engine and older documentation referenced as either a Rehlko Command PRO CH680 or Kohler Command PRO CH680.
Before Ordering the Rehlko CH680-3012
Confirm the identification label on your existing engine before purchasing. The most important information is the complete engine model and specification number. Also verify the equipment model and serial number when possible.
- Verify that your existing engine is CH23S-76634 / PA-76634 or another confirmed compatible application.
- Do not match the replacement based on horsepower alone.
- Confirm the crankshaft and drive configuration.
- Confirm electrical connections and charging-system requirements.
- Confirm the existing air-intake and exhaust configuration.
- Contact Carroll Stream before ordering if any fitment information is unclear.
Need help confirming fitment?
Call Carroll Stream Motor Company at 1-888-208-2088. Have your Walker model, serial number, and the model/specification number from your existing engine available.
Rehlko Command Pro CH680-3012 FAQs
Does the Rehlko CH680-3012 replace the Kohler CH23S-76634?
Yes. The Rehlko Command Pro CH680-3012 / PA-CH680-3012 is the replacement for the PA-76634 Walker engine application associated with CH23S-76634. Verify your complete engine specification before ordering.
Is the Rehlko CH680-3012 the same as the Kohler CH680-3012?
Rehlko is the current brand name for the engine business formerly known as Kohler Engines. As a result, older references may identify this engine as the Kohler Command PRO CH680-3012 while newer products and documentation use the Rehlko name.
How much horsepower does the CH680-3012 have?
The Rehlko Command Pro CH680-3012 is rated at 22.5 horsepower and uses a 674cc OHV V-Twin engine.
How much torque does the Rehlko CH680 produce?
The CH680 produces up to 36.8 ft-lb of peak torque, providing strong output for commercial mowing applications.
What is the displacement of the CH680-3012?
The CH680-3012 has a displacement of 674cc, or 41.1 cubic inches.
What does flush crankshaft mean on the CH680-3012?
The CH680-3012 uses a Walker-specific crankshaft configuration without the conventional extended PTO shaft found on many horizontal-shaft engines. This is one of the primary reasons the exact specification number must be matched when replacing the engine.
Will the CH680-3012 fit every Walker mower?
No. The CH680-3012 is intended for specific Walker applications. Other Walker mower models and engine configurations may require a different Rehlko specification number.
Can I replace the CH680-3012 with another CH680 engine?
Not necessarily. CH680 engines are produced in multiple specification numbers with different crankshafts, charging systems, electrical configurations, and application-specific components. Match the complete specification number rather than only the CH680 engine family.
Does the CH680-3012 have electric start?
Yes. The CH680-3012 uses a 12-volt electric starting system.
What charging system does the CH680-3012 use?
The Walker CH680 configuration uses a 15-amp regulated charging system.
What fuel should I use in the CH680-3012?
Use regular unleaded gasoline with a minimum 87-octane rating. Follow the fuel recommendations in the applicable Rehlko and Walker owner's manuals.
Does the CH680-3012 include a muffler?
No. A muffler is not included with this engine. The applicable Walker exhaust components are used as part of the equipment installation.
Does the CH680-3012 include an air cleaner?
No. This Walker-specific engine configuration is designed for use with the applicable equipment's remote air-cleaner system.
Does the CH680-3012 include a fuel tank?
No. The engine uses the fuel system and fuel tank installed on the compatible equipment.
How much oil does the CH680-3012 hold?
Engine oil capacity is approximately 2.0 US quarts (1.9 liters). Always confirm the proper oil level using the dipstick after filling rather than relying solely on a measured quantity.
How do I know whether the CH680-3012 is the correct engine for my Walker mower?
Locate the identification label on your current engine and record the complete model and specification number. If your engine is identified as CH23S-76634 / PA-76634, the CH680-3012 is the documented replacement. If your numbers differ, contact Carroll Stream before ordering.
