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How to Change Blade Arm on Drum Mower | Expert Guide

How to Change Blade Arm on Drum Mower

Drum mowers are essential agricultural implements designed for efficiently and rapidly cutting grass, hay, or other forage crops. These machines consist of a set of rotating drums equipped with sharp blades, mounted on a horizontal axis, and pulled behind a tractor

One of the key advantages of drum mowers lies in their ability to cover large swaths of land quickly, making them indispensable in modern agriculture. 

Their design allows for a clean and precise cut, promoting faster drying of the forage and ensuring high-quality fodder for livestock. 

Drum mowers are particularly beneficial in areas where traditional scythe or sickle methods may be labor-intensive and time-consuming. 

By streamlining the haymaking process, these machines contribute to increased efficiency, reduced labor costs, and enhanced overall productivity in the agricultural sector.

Understanding the Drum Mower

It typically consists of several key components that work together to efficiently cut and condition the crop. Here are the main components of a drum mower:

Cutter Bar

The cutter bar is a long, horizontal bar with cutting knives or blades attached. It is the main cutting component of the drum mower.

The cutter bar is usually made of steel and is supported by a frame that allows it to move freely along the ground contours.\\

Drums or Discs

Drum mowers have one or more rotating drums or discs that are mounted horizontally and parallel to the ground.

The drums or discs play a crucial role in lifting and guiding the cut crop, allowing it to be neatly laid in rows for drying.

Cutting Knives or Blades

These are the cutting elements attached to the cutter bar. They come in various shapes and designs, and their sharp edges cut through the standing crop as the cutter bar moves along.

Gears and Gearbox

Drum mowers are typically powered by a tractor’s power take-off (PTO). Gears and a gearbox transmit the rotational power from the PTO to the cutter bar and drums or discs.

The gearbox often allows for adjustments to the cutting height and other operational parameters.

Skids or Rollers

Skids or rollers are adjustable components that determine the cutting height of the mower. They can be raised or lowered to control the height at which the crop is cut.

Swath Board or Deflector

This component guides the cut crop to form a neat swath. It can be adjusted to influence the width and shape of the swath.

Safety Features

Drum mowers are equipped with safety features such as guards and shields to prevent accidents. These safety features are crucial to protect the operator and others working in the vicinity.

Frame and Hitch

The frame provides structural support for the mower, and the hitch allows it to be attached to a tractor. The frame must be robust enough to withstand the stresses of cutting heavy crops.

Tensioning System

Some drum mowers have a tensioning system to maintain the proper tension in the belts that drive the cutting components. Proper tension ensures efficient and reliable operation.

Understanding the components of a drum mower is essential for proper operation, maintenance, and troubleshooting. Regular maintenance, such as keeping blades sharp and lubricating moving parts, is important to ensure the longevity and effectiveness of the equipment. 

Additionally, following safety guidelines is crucial when operating any agricultural machinery.

Signs of a Worn Blade Arm

A worn blade arm, often associated with various cutting tools or equipment, can exhibit several signs of wear and tear. The specific signs may vary depending on the type of blade or tool, but here are some common indicators:

Reduced Cutting Performance

If the blade doesn’t cut as efficiently as it used to, it may be a sign of wear. This could manifest as increased resistance, uneven cutting, or a general decline in cutting performance.

Blunt or Dull Edge

A blade that has become blunt or dull is a clear sign of wear. Dull blades can tear or crush material rather than make clean cuts. Check the edge for sharpness by visually inspecting or feeling it carefully.

Chips or Nicks

Physical damage such as chips or nicks on the blade edge can compromise its cutting ability. These imperfections can be caused by hitting hard materials or encountering excessive wear.

Visible Wear Patterns

Examine the blade for visible wear patterns, which can include rounding of the cutting edge or a change in the blade’s shape. This may indicate that the blade has been used extensively and needs attention.

Corrosion or Rust

Corrosion or rust on the blade is not only unsightly but can also affect its performance. Regular maintenance, including proper cleaning and lubrication, can help prevent corrosion.

Vibrations or Unusual Noises

Excessive vibrations or strange noises during operation may suggest that the blade arm is malfunctioning. This could be due to wear in the moving parts or misalignment.

Inconsistent Cuts

If you notice variations in the quality of cuts or if the tool tends to veer off course, it could be an indication of a worn blade arm.

Looseness or Play

If there is noticeable play or looseness in the blade arm, it may be a sign of wear in the bearings, bushings, or other components. This can affect the precision of the cuts.

Increased Heat Production

Excessive heat generation during use can be a sign that the blade is encountering more resistance than usual, possibly due to wear. This can also lead to faster wear and reduced blade life.

Frayed or Torn Edges

For tools like saw blades, frayed or torn edges on the material being cut may indicate that the blade is no longer sharp enough to make clean cuts.

Regular inspection and maintenance of cutting tools are essential to ensure optimal performance and longevity. If you notice any of these signs, it’s advisable to address the issue promptly by either sharpening or replacing the blade or seeking professional assistance.

How to Change Blade Arm on Drum Mower | Step-by-Step Guide

Changing the blade arm on a drum mower typically involves a few straightforward steps. Here is a general guide that you can follow. 

Keep in mind that specific models of drum mowers may have variations in their design, so it’s essential to consult your mower’s manual for precise instructions. Here’s a general guide:

Tools and Materials Needed

Wrenches: Depending on your mower, you might need different sizes.

Socket set: Ensure you have the right size socket for the nuts and bolts.

New Blade Arm: Make sure it’s the correct replacement part for your specific mower.

Safety gear: Wear gloves and safety glasses to protect yourself.\

Safety First

Disconnect the spark plug wire to ensure the mower cannot start accidentally.

Position the Mower

Place the mower on a level surface to provide easy access to the blade arm.

Locate the Blade Arm

Identify the blade arm you want to replace. It’s usually attached to the drum or cutter bar of the mower.

Remove the Retaining Nuts or Bolts

Using the appropriate wrenches or socket set, loosen and remove the nuts or bolts that secure the blade arm to the drum or cutter bar. There may be multiple nuts/bolts holding the arm in place.

Remove the Old Blade Arm

Once the nuts/bolts are removed, take out the old blade arm from its position. Pay attention to how the blade arm is attached, as you’ll need to replicate this when installing the new one.

Install the New Blade Arm

Position the new blade arm in the same orientation as the old one. Make sure any notches or holes align correctly with the mounting points on the drum or cutter bar.

Secure with Nuts or Bolts

Using the wrenches or socket set, tighten the nuts or bolts securely. Ensure they are tightened evenly to maintain balance.

Double-Check Everything

Before using the mower, double-check that all nuts and bolts are tightened securely. Make sure the blade arm is properly aligned and seated.

Reconnect the Spark Plug Wire

Once you’re confident that the blade arm is securely in place, reconnect the spark plug wire.

Test the Mower

Start the mower and run it for a short duration to ensure that the new blade arm is functioning correctly.

Refer to your specific mower’s manual for model-specific instructions or precautions. If you are unsure or encounter difficulties, it’s a good idea to seek assistance from a professional or the manufacturer’s customer support.


In conclusion, changing the blade arm on a drum mower is a task that demands precision and attention to detail. By following the step-by-step guide provided, one can ensure a smooth and efficient replacement process. 

Regular maintenance of the blade arm is crucial for optimal performance and longevity of the drum mower. 

Remember to prioritize safety measures throughout the procedure, such as disengaging power sources and wearing protective gear. 

With a careful approach and adherence to manufacturer guidelines, the replacement can be carried out successfully, allowing the drum mower to continue its essential role in agricultural operations.


How often should I change the blade arm on my drum mower?

Regular maintenance is key to optimal performance. It’s advisable to inspect the blade arm for wear and tear after every 25–30 hours of use. If you notice significant damage or dullness, it’s time to replace the blade arm.

What tools do I need to change the blade arm on a drum mower?

Typically, you’ll need basic tools such as a socket set, wrenches, and a torque wrench. Ensure that you have the appropriate replacement blade arm and refer to your mower’s manual for specific tool requirements and torque specifications.

Can I replace a single blade arm, or do I need to replace all of them at once?

In most cases, you can replace a single-blade arm if it’s damaged or worn. However, it’s a good practice to inspect all blade arms during the replacement process. If others show signs of wear, consider replacing them as well to maintain consistent cutting performance.

Are there any safety precautions I should take when changing the blade arm?

Safety is paramount. Before starting the replacement process, disconnect the spark plug to prevent accidental starts. Wear protective gear, including gloves and safety glasses. 

Can I sharpen the blade arm instead of replacing it?

While some blade arms can be sharpened, it’s often recommended to replace them for optimal performance. Sharpening may compromise the structural integrity of the blade over time. 

If the blade arm has visible damage or has been sharpened multiple times, it’s best to invest in a new one for efficient cutting and safety.


About M. Faisal Riaz

With a robust background spanning 6 years, Faisal is a seasoned professional in digital marketing, advertising, content creation, and SEO strategy. Faisal brings a wealth of expertise to cultivate and amplify the Farmry brand in the digital landscape. Passionate about innovative marketing solutions, Faisal is dedicated to driving Farmry's success in the ever-evolving world of agriculture. 🚜✨ #MeetTheTeam #FarmryLeadership #MarketingMaestro

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