The Toro Model 20374 is a commercial-grade zero-turn riding mower designed for professional landscaping and large property maintenance. This parts manual provides detailed information, diagrams, and part numbers for all components of the mower, including the cutting deck, engine assembly, drive system, electrical system, frame, and controls. It is intended for authorized service technicians and qualified personnel to ensure proper maintenance, repair, and part replacement.
This manual is the official reference for genuine Toro replacement parts for Model 20374. Using non-genuine parts may affect performance, safety, and warranty.
| Safety Symbol | Meaning |
|---|---|
| ⚠️ WARNING | Indicates a hazardous situation which, if not avoided, could result in death or serious injury. |
| ⚠️ CAUTION | Indicates a hazardous situation which, if not avoided, could result in minor or moderate injury. |
| ℹ️ NOTE | Provides helpful information for proper procedure or part identification. |
WARNING! Always disconnect the spark plug wire before performing any maintenance or part replacement. Ensure the mower is on a level surface and the parking brake is engaged.
Complete breakdown of the Toro 24HP V-Twin engine components. Always reference the engine serial number when ordering parts.
CAUTION! Engine parts must be torqued to specifications. Refer to the engine service manual for detailed procedures.
Detailed parts list for the 60-inch fabricated cutting deck, including spindles, blades, and belt routing.
| Component | Part Number | Description |
|---|---|---|
| Main Deck Shell | 104-5678 | 10-Gauge steel, includes mounting brackets |
| Spindle Assembly (Center) | 104-5679 | Complete with bearings and pulley |
| Spindle Assembly (Left/Right) | 104-5680 | Each |
| Blade, 60" Deck | 104-5681 | High-lift, 0.25" thick (each) |
| Deck Drive Belt | 104-5682 | V-Belt, ½" x 125" |
| Deck Lift Linkage Set | 104-5683 | Includes rods, bushings, and pins |
| Baffle Kit | 104-5684 | Airflow improvement kit |
Tip: Always replace blades in sets of three to maintain balance and cutting performance.
Parts for the Hydro-Gear ZT-3400 hydraulic drive system, pump, wheel motors, and linkage.
WARNING! The hydraulic system is under high pressure. Do not disconnect lines before relieving pressure. Use proper fluid only.
Wiring harness, switches, sensors, and battery components.
| Part | Part Number |
|---|---|
| Main Wiring Harness | 106-3456 |
| Ignition Switch | 106-3457 |
| Seat Safety Switch | 106-3458 |
| PTO Clutch Switch | 106-3459 |
| Battery (Group U1) | 106-3460 |
| Starter Solenoid | 106-3461 |
| Headlight Assembly | 106-3462 (each) |
CAUTION! Disconnect the battery negative terminal before servicing any electrical component.
Structural, operator station, and control components.
Common bolts, nuts, washers, and pins used throughout the machine. Sold in kits or individually.
NOTE: Always replace fasteners with the specified grade and type. Do not reuse stretched or damaged bolts.
Alphabetical quick-reference for major parts.
| Part Name | Part Number |
|---|---|
| Air Filter | 103-1238 |
| Blade, Cutting | 104-5681 |
| Deck Belt | 104-5682 |
| Hydraulic Pump | 105-9012 |
| Ignition Switch | 106-3457 |
| Seat Assembly | 107-1113 |
| Spark Plug | 103-1240 |
| Starter Motor | 103-1237 |
Toro Commercial Warranty: 3-year/1500-hour limited warranty on the complete machine. The warranty is valid only when genuine Toro parts are used for repairs. Register your product online at www.toro.com.
Service Support: Contact an authorized Toro Commercial Dealer for service. For technical assistance or to locate a dealer, call 1-800-348-2424 or visit www.toro.com.
| Symptom | Possible Cause | Corrective Action / Part to Check |
|---|---|---|
| Engine cranks but won't start | Fuel, Spark, Air | Check fuel filter (Part # 103-1241), spark plugs (103-1240), air filter (103-1238). |
| Uneven cutting | Deck level, Worn blades | Level deck using adjustment linkage (104-5683). Replace blades in set (104-5681). |
| Loss of power to one drive wheel | Drive belt, Hydraulic motor | Inspect drive belt (105-9015). Check wheel motor (105-9013/105-9014). |
| Deck vibration | Loose/broken spindle, Bent blade | Tighten spindle bolts. Replace spindle assembly (104-5679/104-5680) or blade (104-5681). |
| Electrical failure (no power) | Battery, Safety switch | Test battery (106-3460). Check seat switch (106-3458) and PTO switch (106-3459). |
Reset: For electronic control issues, disconnect battery for 5 minutes to reset system.
Service: 1-800-348-2424; www.toro.com