Yamart 308923014, 120950010

Yamart String Trimmer Auto Head Instruction Manual

For Toro Models 51975, 51955, 51954, 51974, 51976, 51977, 51978, 51988

1. Introduction

This manual provides essential instructions for the safe and effective use, installation, and maintenance of your Yamart String Trimmer Auto Head. This replacement head is designed for compatibility with various Toro string trimmer models, including 51975, 51955, 51954, 51974, 51976, 51977, 51978, and 51988. Please read this manual thoroughly before installation and operation to ensure proper function and safety.

Yamart String Trimmer Auto Head with orange line, shown in use with a string trimmer cutting grass, trimming around a tree, and edging a fence line.

Image 1.1: Yamart String Trimmer Auto Head and typical usage scenarios.

2. Safety Information

Always prioritize safety when working with power tools. Failure to follow these safety guidelines may result in serious injury.

  • Read Your Trimmer's Manual: Always refer to your specific Toro string trimmer's instruction manual for comprehensive safety warnings and operating procedures.
  • Wear Protective Gear: Always wear eye protection (safety glasses or goggles), hearing protection, long pants, sturdy footwear, and gloves when operating a string trimmer.
  • Inspect Before Use: Before each use, inspect the trimmer head for any damage, cracks, or loose parts. Ensure the cutting line is properly installed and not excessively worn.
  • Clear Work Area: Ensure the work area is clear of debris, rocks, and other objects that could be thrown by the trimmer head. Keep bystanders and pets at a safe distance (at least 50 feet/15 meters).
  • Disconnect Power: Always disconnect the spark plug wire (for gas trimmers) or remove the battery/unplug the power cord (for electric trimmers) before performing any maintenance, installation, or clearing clogs.
  • Proper Handling: Hold the trimmer firmly with both hands. Maintain proper footing and balance.
  • Avoid Contact: Never touch the trimmer head or cutting line while the engine/motor is running.

3. Package Contents

Verify that all components are present and undamaged upon opening the package.

  • 1x Yamart String Trimmer Auto Head (Black body with Red cap)
Yamart String Trimmer Auto Head, top-down view, showing the black body and red cap with orange trimmer line extending from both sides.

Image 3.1: Yamart String Trimmer Auto Head (assembled).

Disassembled Yamart String Trimmer Auto Head components, showing the black base and the separate red cap.

Image 3.2: Disassembled components of the trimmer head (base and cap).

4. Setup and Installation

This section details the steps for installing the Yamart String Trimmer Auto Head onto your compatible Toro string trimmer and reloading the cutting line.

4.1 Installing the Trimmer Head

  1. Ensure Safety: Before beginning, ensure your string trimmer is turned off and disconnected from its power source (spark plug wire removed for gas, battery removed or unplugged for electric).
  2. Remove Old Head: Consult your Toro trimmer's manual for specific instructions on removing the existing trimmer head. Typically, this involves holding the shaft to prevent rotation and unscrewing the head counter-clockwise.
  3. Attach New Head: Align the Yamart String Trimmer Auto Head with the trimmer shaft. Screw the new head onto the shaft in a clockwise direction until it is securely tightened. Ensure there is no wobble.
  4. Verify Fit: Gently tug on the head to confirm it is firmly attached.

4.2 Reloading the Cutting Line

The Yamart Auto Head features an easy-to-reload spool design, eliminating the need to disassemble the entire head or turn the trimmer upside down.

  1. Prepare Line: Use appropriate diameter trimmer line as recommended by your Toro trimmer's manual. Cut a length of line (typically 15-20 feet, refer to your trimmer's manual for exact length).
  2. Align Spool: Locate the arrows or alignment marks on the trimmer head and the spool. Rotate the spool until these marks align.
  3. Insert Line: Feed one end of the trimmer line through one of the eyelets on the side of the trimmer head and push it straight through until it exits the opposite eyelet. Pull the line through until an equal length extends from both sides of the head.
  4. Wind Line: While holding the line ends, rotate the red cap of the trimmer head in the direction indicated by the winding arrow (usually clockwise). The line will automatically wind onto the internal spool. Continue winding until only about 6-8 inches of line extend from each eyelet.
  5. Check Line: Ensure the line is securely wound and feeds smoothly.
Internal view of the Yamart String Trimmer Auto Head spool with orange trimmer line wound around it, showing the 'straight shaft' and 'curved shaft' markings.

Image 4.1: Internal spool with trimmer line wound, indicating line path.

5. Operating Instructions

Once the trimmer head is installed and the line is loaded, you can begin operation. Always follow the operating instructions provided in your Toro string trimmer's main manual.

  • Start Trimmer: Start your string trimmer according to its manufacturer's instructions.
  • Advance Line (Auto-Feed): This auto head is designed to advance line automatically when the head is tapped against the ground while the trimmer is running at operating speed. A light tap is usually sufficient. Avoid excessive force.
  • Cutting Technique: Use a sweeping motion to cut grass. Avoid hitting hard surfaces or objects, which can damage the line and the trimmer head.
  • Monitor Line Length: Periodically check the line length. If the line becomes too short, tap the head on the ground to advance more line.

6. Maintenance

Regular maintenance ensures the longevity and optimal performance of your trimmer head.

  • Clean After Use: After each use, ensure the trimmer is off and disconnected from power. Clean any grass clippings, dirt, or debris from the trimmer head. A stiff brush can be used.
  • Inspect for Damage: Regularly inspect the trimmer head for cracks, excessive wear, or other damage. Replace the head if it shows signs of significant wear or damage.
  • Line Storage: Store trimmer line in a cool, dry place to prevent it from becoming brittle.
  • Replace Line: Replace the trimmer line as needed. Do not use line that is too thick or too thin for your trimmer, as this can affect performance and potentially damage the tool.

7. Troubleshooting

This section addresses common issues you might encounter with your Yamart String Trimmer Auto Head.

ProblemPossible CauseSolution
Line does not advance when tapped.
  • Line is tangled or welded together on the spool.
  • Insufficient engine/motor speed.
  • Line is too short.
  • Debris inside the head.
  • Disconnect power, remove cap, untangle/rewind line. Consider using a split design line to reduce tangling.
  • Ensure trimmer is at full operating speed when tapping.
  • Reload new line.
  • Disconnect power, clean out any debris from the head mechanism.
Trimmer head does not fit the shaft.
  • Incorrect model compatibility.
  • Shaft threads are damaged.
  • Verify your Toro trimmer model number against the compatible models listed in this manual (51975, 51954, 51955, 51974, 51976, 51977, 51978, 51988).
  • Inspect trimmer shaft threads for damage. If damaged, consult a qualified service technician.
Excessive vibration during operation.
  • Uneven line length.
  • Damaged trimmer head.
  • Ensure equal lengths of line extend from both sides of the head.
  • Inspect the head for cracks or damage. Replace if necessary.

8. Specifications

  • Product Type: String Trimmer Auto Head
  • Brand: Yamart
  • Material: ABS Plastic
  • Color: Black + Red
  • Compatible Toro Trimmer Models: 51975, 51955, 51954, 51974, 51976, 51977, 51978, 51988 (for straight and curved shaft brushcutters)
  • Replaces Part Numbers: 308923014, 120950010

9. Warranty and Support

For any questions regarding installation, operation, or troubleshooting not covered in this manual, please contact Yamart customer support. Specific warranty details may vary by retailer or region. Please retain your proof of purchase for warranty claims.

For further assistance, refer to the official Yamart website or contact your product retailer.

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