DeWalt 12A-O1T9739 Lawn Mower Manual

The DeWalt 12A-O1T9739 is a high-performance, battery-powered walk-behind lawn mower designed for residential use. It features a brushless motor for extended runtime and durability, a 20-inch steel cutting deck, 6-position single-lever height adjustment, a 7.5Ah FLEXVOLT battery (sold separately), a folding handle for easy storage, and a mulching/bagging side-discharge system. Below are key sections for safety, features, assembly, operation, maintenance, and troubleshooting.

Features at a Glance

Key components: Brushless Motor, 20-inch Steel Deck, Folding Handle, 6-Position Height Adjustment Lever, Battery Port, Mulching Plug, Grass Bag, Safety Key, and Start Lever.

Assembly & Setup

Unpack all parts and inspect for damage. Assembly requires basic tools (included).

1. Attach the Handle: Align lower handle brackets with deck mounts. Insert and tighten provided bolts and wing nuts.
2. Install the Grass Bag: Hook bag frame onto rear deck mounts. Ensure it clicks securely into place.
3. Install Battery: Insert fully charged DeWalt FLEXVOLT battery into the battery port until it clicks. Ensure battery is compatible.
4. Attach Mulching Plug (if desired): For mulching, insert the mulching plug into the side discharge chute.
5. Adjust Cutting Height: Move the single lever to your desired setting (1-6) before starting.

WARNING! Do not install battery or attempt to start mower until assembly is complete and you have read the Safety section.

First-Time Operation

Before first mow, ensure lawn is clear of debris like sticks, stones, and toys.

1. Insert Safety Key: Push the Safety Key fully into the slot on the control panel.
2. Engage Start Lever: Hold down the safety bail (lever) on the upper handle against the handle grip.
3. Start Mowing: While holding the bail, pull the start lever towards you. The blade will engage. Release either lever to stop the blade instantly.
4. Mowing Pattern: Mow in straight, overlapping passes. For best results, mow when grass is dry.
5. Empty Bag: Stop mower, wait for blade to stop completely, and empty grass bag when indicator shows full.

CAUTION! Always wear sturdy shoes and eye protection. Never operate with the grass bag or mulching plug removed unless using side discharge.

Specifications

• Model: DeWalt 12A-O1T9739
• Power Source: DeWalt 20V/60V FLEXVOLT Battery (sold separately)
• Cutting Width: 20 inches
• Cutting Heights: 6 positions, 1.5" to 4" (38 mm to 102 mm)
• Deck Material: Powder-coated steel
• Motor Type: Brushless
• Wheels: 8" rear, 7" front
• Weight (without battery): Approximately 65 lbs (29.5 kg)
• Grass Capacity: 1.9 bushels (67 L)
• Charging Time: Varies by charger (typically 60 minutes for rapid charger)

Controls and Settings

Primary controls are located on the upper handle for safe, intuitive operation.

Upper Handle: Start/Safety Bail Lever, Start Lever, Height Adjustment Lever.

Deck/Control Panel: Battery Port, Safety Key Slot, Side Discharge Chute.

Operation: Both the Safety Bail (must be held against handle) and the Start Lever (pulled back) must be engaged for the blade to spin. Releasing either stops the blade.

Height Adjustment: Move the single lever to one of six numbered positions. Adjust only when mower is off and blade is stopped.

Battery Gauge: Press the button on the FLEXVOLT battery to check charge level via LED indicators.

Cutting & Height Adjustment

Choose between mulching, bagging, or side discharge for your lawn's needs.

1. Mulching: Install mulching plug. Cuts clippings finely and returns them to the lawn as nutrient-rich mulch.
2. Bagging: Attach grass bag. Collects clippings for a clean finish, ideal when grass is tall or wet.
3. Side Discharge: Remove both bag and plug. Discharges clippings to the side for later raking, useful for very tall grass.
4. Adjusting Height: Determine desired grass length. Move adjustment lever to corresponding position (1=lowest, 6=highest). Ensure all wheels lock at the same height.

Tip: Never remove more than 1/3 of the grass blade height in a single mow to maintain lawn health.

Maintenance & Storage

Regular maintenance ensures optimal performance and longevity.

1. After Each Use: Clean grass clippings from under the deck (with mower OFF and battery removed). Wipe down the mower.
2. Blade Care: Periodically inspect blade for dullness or damage. A sharp blade provides a cleaner cut and is safer. Replace bent or damaged blades immediately.
3. Battery Care: Store battery in a cool, dry place. Charge fully before long-term storage.
4. End-of-Season Storage: Clean thoroughly. Remove and fully charge battery. Store in a dry location. Fold handle to save space.
5. Wheel & Bearing Check: Ensure wheels spin freely. Lubricate axle points if necessary (consult manual).

WARNING! Always disconnect the battery before performing any maintenance, especially cleaning the deck or inspecting the blade.

Safety Information

This mower is equipped with safety features that must not be altered or bypassed.

• Read the manual completely before assembly or use.
• Always wear appropriate personal protection: safety glasses, sturdy footwear, long pants.
• Clear the mowing area of objects that could be thrown by the blade (stones, toys, wire).
• Do not mow wet grass. Be cautious on slopes; mow across the face of slopes, not up and down.
• Never allow children or pets in the area while mowing.
• Use only DeWalt FLEXVOLT batteries and chargers specified for this tool.
• The blade coast for a few seconds after release. Wait for complete stop before crossing gravel drives, roads, or when leaving the mower unattended.

DANGER! Keep hands and feet away from the rotating blade and discharge opening. Never lift or carry the mower while it is running.

Warranty & Support

DeWalt offers a limited warranty for this product. Proof of purchase is required.

Warranty Period: Refer to the warranty card included with your product for specific duration and terms.

Service: For service, repair, or replacement parts, contact an authorized DeWalt service center. Do not attempt to repair the mower yourself beyond basic maintenance described in this manual.

Support: For technical support, troubleshooting, or to locate a service center:

• Visit: www.dewalt.com
• Call: 1-800-4-DEWALT (1-800-433-9258)

Troubleshooting

Reset: If the mower overheats or is overloaded, it may shut off. Remove battery, wait 15 minutes, then reinstall to reset.

Service: For persistent electrical or mechanical issues, contact DeWalt service.