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National Mower Essential Backlapping and Vertical Mowing Techniques for Your Mower

Models: 99500500-8400

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Test for end play periodically by trying to move the reel from side to side in the frame. If there is any movement, end play is present.

1.Loosen the lock nut on the adjustment screw (7, Figure 17) and (Figure 18), (inside right end of the reel) and turn adjustment bolt in 1/2 turn or less. Do not over tighten as excessive bearing wear can occur.

2.Test again for endplay. If reel is rotating freely and endplay can not be detected, retighten the locking nut on adjustment bolt.

Locknut and Screw

Figure 18

VERTICAL MOWING UNIT - BLADE CHANGING

1.To change the blades, remove the vertical mowing unit from the frame. Unbolt the (2) hangers (see Parts Manual) from the frame.

2.Remove bearing from the hangers. Remove by loosening the bearing collet setscrews.

NOTE: It is also advised to check the bearings for wear and replace if necessary.

3.Remove nut from the shaft and slide the blade and spacer off.

4.Reassemble with new blades. Make sure you time the blades so they are on a spiral and so that the blades are pointed in the proper direction. Check to make sure there is no side play with the blades when tightening the nut.

5.Re-attach the vertical mowing unit to the frame.

BACKLAPPING PROCEDURE

Backlapping is a very important step in maintaining sharp reel blades on the rear and wing mowers.

This procedure should be performed when the reel blades and bedknife become slightly rounded and the grass cannot be cut cleanly after adjusting the reel to bedknife clearance (see REEL TO BEDKNIFE ADJUSTMENT on page 18).

DANGER: Be extremely careful not to let tools, your fingers, or clothing get caught in the reels. Use approved safety glasses to protect eyes from flying particles and abrasives.

1.Make sure to adjust the reel to the bedknife so that the reel is parallel with the bedknife and light contact is maintained.

2.Reels must be run in reverse direction to be lapped. Remove drive belts and attach a backlapping machine to the reel. Follow the instructions furnished by the backlapping machine manufacturer.

3.With reel running, apply the lapping compound using a 2” or 3” wide brush. Apply the compound evenly to the mowing blades.

4.Stop the reel and examine both bedknife and reel blades to see that the cutting edges are uniformly sharp. If not, gradually tighten nut adjuster (see REEL TO BEDKNIFE ADJUSTMENT on page 18), and repeat step 3 above until the proper sharpness results.

5.Rinse off the compound thoroughly with water to remove all abrasives. Check for sharpness and readjust the bedknife if necessary.

6.Check reel adjustment on each mower and adjust if necessary so that they will cut paper cleanly across the full length of the bedknife when paper is held 90° to the bedknife and pinched when held horizontally.

Many types of compounds are available for lapping. However, we recommend a good pre-mixed water-soluble compound. Premixed compound saves the time required to mix, eliminates the waste, and is available in all grit ranges from coarse to extra fine.

Contact your local Dealer for types and ordering information.

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National Mower 99500500-8400 manual Vertical Mowing Unit Blade Changing, Backlapping Procedure
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99500500-8400 specifications

The National Mower 99500500-8400 is an advanced lawn care solution that epitomizes efficiency and innovation for users who demand high performance from their gardening equipment. Designed for residential and light commercial use, this mower combines state-of-the-art technology with robust features to ensure a seamless mowing experience.

One of the standout features of the National Mower 99500500-8400 is its powerful engine. Equipped with a high-output, fuel-efficient engine, this mower delivers consistent power that translates into excellent cutting performance. This ensures that the mower can tackle various grass types and densities, making it useful for both manicured lawns and rugged terrains.

The 99500500-8400 boasts a durable cutting deck made from high-quality materials that resist corrosion and wear. This deck is designed with precision engineering to enhance airflow for optimal grass clipping discharge, resulting in clean, even cuts regardless of lawn conditions. Furthermore, the adjustable cutting height feature allows users to customize the mower’s settings, enabling them to achieve the desired grass length for their specific needs.

In terms of technology, the National Mower incorporates advanced safety measures to enhance user experience. The intuitive safety features include a blade brake that stops the blades within seconds when the operator releases the handle, reducing the risk of accidents. Additionally, the ergonomic handle design ensures comfort during use, allowing for prolonged operation without strain.

Another impressive characteristic of the 99500500-8400 is its ease of maintenance. The mower is engineered for quick blade sharpening and simple access to engine components, making routine upkeep straightforward for users. This is complemented by a lightweight design that enhances maneuverability, allowing users to navigate through tight spots and around obstacles with ease.

Finally, the National Mower 99500500-8400 is designed with environmental sustainability in mind. The fuel-efficient engine minimizes emissions, making it an eco-friendly choice for consumers looking to maintain their lawns without compromising on their commitment to the environment.

In conclusion, the National Mower 99500500-8400 stands out as a reliable, high-performance lawn mower featuring robust power, safety, and user-friendly characteristics ideal for any homeowner or light commercial user. Its blend of innovative technology and practical design makes it a must-have for efficient lawn care.