Introduction
This service manual provides comprehensive instructions for the maintenance, repair, and overhaul of Gravely Convertible Walk Behind Mowers, specifically covering models 520, 521, 522, 524, 526, 546, 564, and 566. It is designed for use by qualified service technicians and individuals possessing a thorough understanding of mechanical systems and repair procedures. Adherence to the guidelines and procedures outlined herein is essential for ensuring safe operation, optimal performance, and extending the service life of your equipment.
Always consult the safety precautions section before commencing any service or maintenance tasks.
Safety Precautions
Prior to initiating any service work, ensure the engine is completely shut off, the spark plug wire is disconnected to prevent accidental starting, and all moving components have ceased motion. Always wear appropriate personal protective equipment (PPE), including safety glasses, work gloves, and hearing protection. Utilize correct tools for each task and strictly adhere to manufacturer's torque specifications for all fasteners.
- Disconnect the spark plug wire before any inspection or service.
- Allow the engine and muffler to cool down completely before handling.
- When working underneath the machine, use stable and approved lifting devices.
- Maintain a clean, organized, and well-lit work environment.
- Never operate the engine in an enclosed area without adequate ventilation to prevent carbon monoxide poisoning.
Engine Service and Maintenance
This section details routine engine maintenance, inspection, and repair procedures for optimal engine performance and longevity.
Engine Oil Change
- Operate the engine for a few minutes to warm the oil, which aids in complete drainage.
- Position a suitable oil drain pan beneath the engine's oil drain plug.
- Remove the oil drain plug and allow all engine oil to drain thoroughly.
- Reinstall the drain plug, tightening it to the torque specified in the engine manufacturer's guidelines.
- Remove the oil fill cap and add the recommended type and volume of new engine oil.
- Verify the oil level using the dipstick and securely replace the oil fill cap.
Figure 2: Engine diagram highlighting oil drain and fill points.
Spark Plug Inspection and Replacement
Inspect the spark plug every 50 hours of operation or at least once annually. Replace the spark plug if the electrodes show signs of wear, fouling, or damage.
- Carefully remove the spark plug wire from the spark plug.
- Using a spark plug wrench, remove the existing spark plug.
- Examine the removed spark plug for indications of engine operating conditions (e.g., carbon buildup, oil fouling).
- Adjust the gap of the new spark plug to the precise specification provided in the 'Specifications' section.
- Install the new spark plug by hand to prevent cross-threading, then tighten it with a wrench to the recommended torque.
- Firmly reconnect the spark plug wire.
Transmission and Drive System Service
This section covers detailed procedures for inspecting, adjusting, and repairing the transmission and associated drive components to ensure smooth power delivery.
Drive Belt Tension Adjustment
Maintaining correct drive belt tension is critical for efficient power transfer and preventing premature belt wear. Check belt tension at recommended service intervals.
- Locate the drive belt and its tensioner assembly.
- Loosen the necessary adjustment bolts on the tensioner mechanism.
- Adjust the tensioner until the belt deflection measures within specified limits (typically 1/2 inch when moderate thumb pressure is applied midway between pulleys).
- Securely tighten all adjustment bolts once the correct tension is achieved.
Figure 3: Drive belt and tensioner assembly location.
Cutting Deck Service
Instructions for maintaining, sharpening, and replacing cutting blades, along with procedures for leveling the cutting deck and general deck care.
Cutting Blade Sharpening and Replacement
- Ensure the spark plug wire is disconnected to prevent accidental engine start.
- Carefully tilt the mower or use a suitable lift to gain safe access to the cutting blades.
- Insert a block of wood between the blade and the deck to prevent the blade from rotating during removal.
- Remove the blade retaining bolt and washer.
- Sharpen blades using a file or grinder, carefully maintaining the original cutting angle. After sharpening, ensure blades are balanced to prevent vibration.
- Install sharpened or new blades, verifying that the cutting edge is oriented correctly. Tighten the retaining bolt to the specified torque.
Troubleshooting Guide
This section offers diagnostic assistance and solutions for common operational and mechanical issues that may arise with your Gravely mower.
| Problem | Possible Cause | Solution |
|---|---|---|
| Engine fails to start | Insufficient fuel; fouled or incorrect spark plug; carburetor malfunction | Verify fuel level; clean or replace spark plug; inspect and clean carburetor |
| Substandard cutting quality | Dull or damaged blades; improper cutting deck height; accumulation of debris under deck | Sharpen or replace blades; adjust deck height according to terrain; thoroughly clean the underside of the cutting deck |
| Excessive machine vibration | Unbalanced or bent blade; loose mounting fasteners; bent engine crankshaft | Balance or replace blade; inspect and tighten all fasteners; have crankshaft inspected by a qualified technician |
Specifications
Key technical specifications for Gravely Convertible Walk Behind Mowers, applicable to models 520, 521, 522, 524, 526, 546, 564, and 566. Always refer to specific engine manufacturer's manual for precise engine specifications.
| Component/Parameter | Specification/Recommendation |
|---|---|
| Recommended Engine Oil Type | SAE 30 (for temperatures above 32°F/0°C), SAE 5W-30 (for temperatures below 32°F/0°C) |
| Engine Oil Capacity | Consult specific engine model manual (typically ranges from 1.5 to 2 quarts) |
| Spark Plug Electrode Gap | 0.030 inches (0.76 mm) |
| Cutting Blade Retaining Bolt Torque | 45-50 ft-lbs (61-68 Nm) |
| Recommended Fuel Type | Unleaded gasoline, minimum 87 octane |
Warranty Information
This service manual focuses on repair and maintenance procedures and does not contain specific warranty details for your Gravely Convertible Walk Behind Mower. For comprehensive warranty information, please refer to the original owner's manual that accompanied your equipment at the time of purchase, or contact an authorized Gravely dealer. Warranty terms and conditions are subject to variation based on the specific model and date of purchase.
Customer Support
For further technical assistance, inquiries regarding genuine Gravely replacement parts, or to locate your nearest authorized service center, please visit the official Gravely website or contact their dedicated customer support line. When contacting support, always have your specific mower model number and serial number readily available to facilitate efficient service.
Official Gravely Website: www.gravely.com
Find an Authorized Dealer: Gravely Dealer Locator