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Service - Cutting Units


Avoid Injury from Contacting Blades

c CAUTION: Avoid injury! Residual hydraulic pressure in the system can cause cutting cylinder rotation when cutting unit blockage is removed.

• Before you dismount to unplug or service cutting units:

– Stop machine.

– Disengage PTO by pressing down on PTO switch.

– Lock the park brake.

– Lower cutting units to the ground.

– Stop engine and remove key.

– Wait for reels to stop.

• Keep hands, feet, and clothing away from cutting units when engine is running.

Removing and Installing Cutting Units

Removing Cutting Units

c CAUTION: Avoid injury! Always wear protective gloves when working on or near the reel or bed knife. Severe personal injury can result from contact with the sharp cutting edges.

Manually rotating one reel can cause another reel to rotate.

1. Park machine safely. (See Parking Safely in the SAFETY section.)


MX23243

2. Remove two flange hex nuts (A) and remove reel drive motor (B).

3. Remove quick-lock pin (C).

4. Roll cutting unit forward away from lift arm.


MX23656

5. Inspect inside of reel bearing housing (D) for grease. Add John Deere Special Purpose HD Cornhead Grease to housing if additional lubrication is needed.

6. Check splined motor/reel coupling (E) for wear. Replace if necessary. Make sure coupling is lubricated with grease and remains in position on reel shaft.

7. Repeat procedure for other cutting units if necessary.

Installing Cutting Units

c CAUTION: Avoid injury! Machine component is heavy. Use a safe lifting device or get an assistant to help lift and hold component into place for installation.

1. Install cutting unit yoke onto lift arm and install quick-lock pin.

NOTE: It may be necessary to rotate the reel slightly so the splines in the drive coupler and reel drive motor align.

Do not force the splines to engage by tightening flange hex nuts. Damage to cutting unit and/or reel drive motor will result.

2. Install reel drive motor onto cutting unit and secure with two flange hex nuts.

3. Repeat procedure for other cutting units if necessary.

Removing and Installing Front Roller

Removing


MX23662

1. Remove the nuts and washers (A) securing the roller adjustment brackets to the cutter frame. Remove roller with brackets from cutting unit.

2. Loosen jam nut and set screw (B) (left side only). Slide the roller adjustment brackets off the roller.

3. Remove grease fittings from each end of roller.

Installing


M56473

1. Slide adjustment brackets (A) onto roller shaft (bracket with set screw on left side).

2. Secure each bracket to frame with carriage bolt (B), nut (C), and washer (D).

3. Center the roller between the brackets and tighten set screw (E). Tighten jam nut (F).

4. Adjust height-of-cut.

Removing and Installing Rear Roller

Removing


MX23663

1. Remove the nuts and washers (A) securing the roller adjustment brackets to the cutter frame. Remove roller with brackets from cutting unit.

2. Loosen jam nut and set screw (B) (right side only). Slide the roller adjustment brackets off the roller.

3. Remove grease fittings from each end of roller.

Installing


M56473

1. Slide adjustment brackets (A) onto roller shaft (bracket with set screw on right side).

2. Secure each bracket to frame with carriage bolt (B), nut (C), and washer (D).

3. Center the roller between the brackets and tighten set screw (E). Tighten jam nut (F).

4. Adjust height-of-cut.

Adjusting Cutting Units

1. Park the machine safely. (See Parking Safely in the SAFETY section.)

NOTE: Adjustments may affect each other. It is important that adjustments be made in the following sequence.

2. Adjust two-bolt gauge bar for desired height-of-cut.

3. Set units for the height-of-cut.

4. Adjust the reel-to-bed knife clearance.

5. Perform the backlapping operation.

IMPORTANT: Avoid damage! Do not allow the reel to interfere with the bed knife. Interference will cause heating and can damage reel and bed knife.


6. Adjust reel-to-bed knife clearance.

Adjusting Height-of-Cut

The adjustments used to set the height-of-cut can be divided into three categories:

1. Height-of-cut range.

2. Height-of-cut adjustments NOT in 3.2 mm (1/8 in.) increments requiring use of a two-bolt gauge bar.

3. Height-of-cut adjustments THAT ARE IN 3.2 mm (1/8 in.) increments using adjuster racks - does not require subsequent use of two-bolt gauge bar.

NOTE: Using a single-bolt adjusting gauge bar will not ensure parallelism between rollers and may result in uneven height-of-cut.

In general, these adjustments should be carried out in the above listed order to ensure the rollers are parallel to the bed knife and provide the highest quality cut possible.

c CAUTION: Avoid injury! Always wear protective gloves when working on or near the reel or bed knife. Severe personal injury can result from contact with the sharp cutting edges.

Manually rotating one reel can cause another reel to rotate.

NOTE: All cutting units must be set at the same height to obtain an even cut. Floating units will not provide a quality cut in grass over approximately 38 mm (1-1/2 in.) tall.

Setting Height-of-Cut Range

NOTE: Height-of-cut range must be set to the same position at all four adjuster racks.

1. Park the machine safely. (See Parking Safely in the SAFETY section.)

2. Raise cutting units or remove as desired.


MX24002

3. Loosen top nuts (A) and bottom nuts (B).

4. Remove nuts (C) and roller support (D).

5. Remove adjuster racks (E) from cutting unit.


MX24018

6. The cutting unit has two height-of-cut ranges to which it can be set.

• The carriage bolts must be installed in top hole (F) of adjuster rack (E) for a height-of-cut range between 9.5 and 38 mm (3/8 and 1-1/2 in.).

• The carriage bolts must be installed in bottom hole (G) of adjuster rack (E) for a height-of-cut range between 38 and 89 mm (1-1/2 and 3-1/2 in.).

NOTE: Each notch on the adjuster rack equals 3.2 mm (1/8 in.). Set rear roller support first and then front roller support.

7. Install adjuster rack, roller support and hardware, ensuring each roller support is set on the same notch of adjuster rack.

For adjustments that are not in 3.2 mm (1/8 in.) increments:


M56226, MX24017

1. To raise rollers, loosen flange head bolt (H).

NOTE: If rollers are adjusted to a position such that the gauge bar cannot be installed, raise either the front or rear roller or both to allow installation of the gauge bar.

2. Loosen bottom adjusting nuts (B).

3. Turn top adjusting nut (A) to the right (clockwise) on each end of cutting unit, alternating back and forth.

4. If adjustment is limited by slots at flange head bolts (H), raise or lower each roller support one notch as needed.

5. Prepare a two-bolt gauge bar.

NOTE: Using a single-bolt adjusting gauge bar will not ensure parallelism between rollers and may result in uneven height-of-cut.


M47195

• Loosen wing nut (I). Set height-of-cut by measuring from the top of the gauge to the bottom of the head of the hex head bolt (J). Lock wing nut (I).


M56227

Picture Note: Cutting unit is upside down for photo clarity.

6. Hook head of hex head bolt (J) over edge of bed knife.

7. Loosen wing nut (K). Turn hex head bolt (L) until gauge is parallel with bed knife.


M47250

8. Measure distance between front (M) and rear (N) of the bottom of the bed knife to top of gauge. When the distance is equal, the gauge bar is parallel to the bed knife.

9. Adjust hex head bolt (L) until gauge bar is parallel to the bed knife. Tighten wing nut (K) ensuring hex head bolt (L) does not turn.

IMPORTANT: Avoid damage! Do not turn nuts on front adjuster beyond where the roller just touches the gauge bar or the bar will bend.


NOTE: When adjusting rollers, move both ends of roller equally, alternating from end to end. This will keep the adjusters from binding.


M56225

10. Grooved Rollers: Loosen bottom nut (B). Carefully turn top adjusting nut (A) until the first two ribs (O) of the machined portion of the roller just touch the gauge.

This is determined by turning the roller and listening for the scratching sound from roller on gauge bar.


M56228

11. Solid Rollers: Loosen bottom nut (B). Carefully turn top adjusting nut (A) until the solid center piece of the roller (P) (not the end caps) just touches the gauge.

This is determined by turning the roller and listening for the scratching sound. On rollers with scrapers, a screwdriver can be inserted in slot of the scraper to lift it out of the way to better clean the scraper and roller. Hook the screwdriver handle under the reel housing to hold the scraper.

12. After setting front and rear rollers on one end, tighten all hardware and recheck all gauge settings. Adjust height-of-cut if necessary.

13. Follow same procedure for the opposite end of bed knife and rollers.

14. After setting second end, go back and check first settings to be sure they haven’t moved. Adjust if necessary. Gauge can snugly be placed into position on either end when properly adjusted.

For quick adjustments that are in 3.2 mm (1/8 in.) increments:

This adjustment is to be used only after the rollers have been adjusted using a two-bolt gauge bar and are parallel to the bed knife.

NOTE: Each notch in the adjuster rack equals 3.2 mm (1/8 in.). Set rear roller first and then front roller.


MX24002

1. Loosen nuts (C) and slide adjusters equally to the desired height-of-cut.

NOTE: When adjusting rollers, move both ends of roller equally, alternating from end to end. This will keep the adjusters from binding.

2. Tighten hardware.

For quick adjustments that are in 1.6 mm (1/16 in.) increments:

This adjustment is to be used only after the rollers have been adjusted using a two-bolt gauge bar and are parallel to the bed knife.

NOTE: Adjust only front or only rear roller one notch. Do not adjust both rollers or height-of-cut adjustment will not equal 1.6 mm (1/16 in.).


MX24002

1. Loosen nuts (C) and slide adjusters one notch.

NOTE: Adjusting height-of-cut in this manner changes the bed knife attitude.

2. Tighten hardware.

Bed Knife Attitude

Bed knife attitude is the angle of attack at which the bed knife approaches the turf.

It is possible to set the height-of-cut to incorporate varying degrees of bed knife attitude.

• In general, the more the front of the cutting unit is pitched down, the more aggressive the bed knife attitude.

• Aggressive bed knife settings are accomplished by setting the front roller slightly higher than the rear roller relative to the bed knife.

• The need to incorporate a more or less aggressive bed knife attitude is determined by the height-of-cut desired and the cutting conditions.

• Very short height-of-cut settings require a more aggressive bed knife attitude.

Adjusting Reel-to-Bed Knife Clearance

This adjustment, combined with the backlapping operation, will ensure a clean cut as well as reduce wear, take less power, and reduce downtime.

Reel-to-bed knife clearance should be checked before and after backlapping.

c CAUTION: Avoid injury! Always wear protective gloves when working on or near the reel or bed knife. Severe personal injury can result from contact with the sharp cutting edges.

Manually rotating one reel can cause another reel to rotate.


M47199

1. It is important to have a 6.5? relief angle on the top surface (A) and a 5? relief angle on the front surface (B).

Otherwise, remove bed knife and bed knife support and have them ground as a complete unit.


E35559

2. Use feeler gauges to set recommended reel-to-bed knife clearance (B) in the range for the grass to be cut.

Finer textured grasses, such as rye grass or bent grass, require a close setting, but the setting should not be less than 0.03-0.05 mm (0.001-0.002 in.). They also require a sharp reel and bed knife to cut properly.


M47200

3. Place a 0.03-0.05 mm (0.001-0.002 in.) feeler gauge (C) between bed knife and reel. Check at both ends of reel and two areas near the center.


M56226

4. If adjustment is necessary, loosen jam nut (D) and adjusting nut (E) at both ends of the reel, equal amounts, preferably one flat at a time.

• Turn adjusting nuts (E) clockwise to raise reel.

• Turn jam nut (D) clockwise to lower reel.

• Adjust reel until 0.03-0.05 mm (0.001-0.002 in.) is reached across the entire reel and bed knife.

IMPORTANT: Avoid damage! Do not allow the reel to interfere with the bed knife. Interference will cause heating and can damage reel and bed knife.


5. Tighten adjusting nuts (E) and jam nuts (D). Recheck to ensure reel has not moved. Readjust if necessary.

Backlapping Cutting Units

IMPORTANT: Avoid damage! The reel-to-bed knife clearance should be adjusted to approximately 0.076mm (0.003 in.) at the ends.


Backlapping cutting units must be done on a routine basis to prolong reel life, prevent down time, and provide sharp cutting action.

1. Lock park brake and start engine.

2. Lower all cutting units to the ground.

c CAUTION: Avoid injury! Keep hands and feet away while machine is operating. Never touch any blade while engine is running.

NOTE: Cutting units are backlapped all at once.

3. Lift hood to gain access to backlapping valve.


MX23358

4. Put machine in backlapping mode by pushing lock detent (A) down and pulling up on Forward-Reverse knob (B).

5. With operator off seat, place mow-transport lever in the mow position. The reels will begin to rotate in the opposite direction of normal operation only when the operator is off the seat.


MX23358

6. Rotate flow control knob (C) to adjust reel speed.

• Turn knob clockwise to decrease reel speed.

• Turn knob counterclockwise to increase reel speed.

7. Adjust reel speed slow enough so grinding compound will not be thrown off during backlapping.


M79054

8. Using a long-handled brush, carefully apply reel sharpening compound, uniformly, from one end of the reel to the other.

9. Repeat application in opposite direction. Allow unit to continue running backwards until reel is quiet.

10. Periodically move mow-transport lever to the transport position and shut engine off to visually check blade appearance.

11. Wash away backlapping compound with water before checking reel-to-bed knife clearance.


M56226

12. Adjust reel-to-bed knife clearance by loosening jam nut (D) and turning adjusting nut (E) and jam nut to proper clearance on both ends.

13. Check for uniform clearance across entire bed knife. If clearance is not uniform, repeat steps 5 through 12 until clearance is uniform across entire bed knife.

IMPORTANT: Avoid damage! Turn flow control knob fully to the left (counterclockwise) when backlapping operation is complete.


14. Move mow-transport lever to the transport position and shut off engine. Turn flow control knob fully counterclockwise.

IMPORTANT: Avoid damage! Do not operate cutting reels in the forward direction until reel sharpening compound is washed from the unit. Unless properly washed, the reels can be dulled by the compound.


15. Push Forward-Reverse knob down to resume normal operation.

Grinding Reel and Bed Knife

Reel and Bed Knife Relationship

Reel mowers are precision machines requiring daily maintenance to maintain the well-groomed appearance of turfgrass. The scissor-like shearing action, that only a reel mower is capable of achieving, is only possible if the reel and bed knife are sharp and the reel-to-bed knife clearance is maintained.

Close examination of the reel-to-bed knife relationship reveals two square edges passing one another with approximately 0.051 mm (0.002 in.) clearance. There are several reasons why this clearance is necessary.

• When the reel is allowed to contact the bed knife, the square (sharp) edges of the reel and bed knife will roll over, becoming dull.

• Contact between the reel and bed knife generates heat. Heat generated through this contact will distort the shape of the bed knife. Distortion causes the bed knife to draw closer to the reel, resulting in more rollover of the cutting surfaces and more heat generated in the bed knife.

• Drag produced by an improperly adjusted cutting unit may result in an unacceptable clip ratio, undue strain on drive mechanisms and premature wear of the cutting unit.

Reasons for Grinding

• To restore the cylindrical shape of a reel that has become cone-shaped due to improper adjustment of the reel-to-bed knife clearance or worn reel bearings.

• To restore the edge when the grass is not being cut across the entire length of the bed knife, evidenced by streaks of grass left after the mower has passed. Usually the result of nicked blades caused by hitting foreign objects in the grass.

• To restore the edge when the lack of frequent backlapping allowed the edge to be rounded beyond the capability of the backlapping procedure to restore the edge.

• To restore the edge when the reel-to-bed knife clearance has been improperly adjusted (reel contacting bed knife).

Cutting action begins as the bed knife positions the grass to be cut at the cutting edge. The reel then pulls the grass toward the bed knife where it is sheared by the cutting edges as they pass one another.

In order for the grass to be cut at the proper height, it must contact the bed knife at the cutting edge. This is accomplished by grinding a 5? relief angle on the front face of the bed knife. Without a relief angle, the blade of grass will contact the lower edge of the bed knife and be bent over at too much of an angle prior to being cut. In the case of mowing greens, where very small cuts are being taken, the reel may not capture the grass at all, and no grass will be cut.

Although some spin grinding machine manufacturers say backlapping is not necessary, John Deere recommends backlapping after spin grinding to remove burrs and rough edges left from the spin grinding procedure. Backlapping produces a honed edge that will cut the grass evenly and leave the tops of the grass with clean, straight edges.

It is important to note, dull cutting edges will tear rather than shear the grass drawn into the bed knife. This will shock the grass plant and retard its growth.

Grinding the Bed Knife

NOTE: Bed knife and support assembly must be ground as a complete unit.


M47199

1. When grinding the bed knife, it is important to have a 6.5? relief angle on the top surface (A) and a 5? relief angle on the front surface (B).

2. Put entire bed knife support and bed knife in a suitable grinder and grind until material is consistently removed from the entire length of the top and front surfaces of the bed knife.

Grinding the Reel

MIF

John Deere recommends relief grinding the reels after spin grinding for these reasons:

• Reduced blade contact area results in less friction, requiring less horsepower to drive the reel and increases fuel efficiency.

• Ensures longer wear life.

• Less time is required to backlap.

• Reduces pulling and tearing of the grass as the unit gets dull by use.

• Provides an area for backlapping compound to be trapped to more effectively backlap reels.

• Relief grinding removes metal from the trailing edge of the blade, forming an angle (relief angle) to reduce the contact area of the cutting edges.

• Because of the relief grind it is possible, with backlapping, to true a reel (make it round) if a blade is 0.025-0.051 mm (0.001-0.002 in.) too high.

Replacing Bed Knife


M56224

1. Remove six cap screws (A) attaching bed knife support to cutting unit housing, three on each end.

2. Remove bed knife support, with bed knife attached from cutting unit housing.

3. Remove and discard screws and nuts attaching bed knife to support. Discard bed knife.

4. Remove debris, corrosion, and rust from bottom surface of bed knife support.

5. Install end screws (B), tighten to secure knife to support, to properly position knife.

6. Install rest of screws and nuts.

7. Tighten nuts to 1/2 torque, approximately 26 N•m (19 lb-ft.), starting from the center and work out towards the ends.

8. Finish tightening to full torque, 45 N•m (34 lb-ft), starting from the center and work out towards the ends. Minimum torque is 35 N•m (26 lb-ft).

9. Put bed knife support and bed knife in a suitable grinder and grind until knife is flat and uniformly ground across the top surface.


M56226

10. Raise reel, by turning the reel adjusting nut (C) to the right (clockwise) and nut (D) to the left (counterclockwise), until the knife and support can be installed.


M56224

11. Reinstall the bed knife support assembly, and snug cap screws (A) on both ends.

12. Tap both ends of bed knife (E) away from reel with a brass hammer to remove any play in bed knife support. Tighten cap screws to 43 N•m (32 lb-ft.).

13. Set the height-of-cut. See Adjusting Height-Of-Cut in this section.

14. Adjust the reel-to-bed knife. See Adjusting Reel-To-Bed knife in this section.

15. Backlap reel. See Backlapping Cutting Units in this section.

16. Check the height-of-cut and adjust as necessary. See Adjusting Height-Of-Cut in this section.