National Mower IM25 - Manual (Page 5)

IM25OM-1/2000-250
6
FIGURE D
FIGURE E
Backlapping gears are
shown disengaged.
The gears must be in
this position when
mowing.
Raise mower up until drive roller
clears the ground.
Backlapping gears are shown
engaged. The gears must be in
this position when backlapping.
Backlapping
Backlapping is a very important step in maintaining
sharp reel blades on the mower. This procedure should
be performed when the reel blades and bed knife become
slightly rounded and the turf is not cut cleanly after a
slight bed knife adjustment. Also, after grinding the bed
knife and reel, backlapping should be done to establish a
perfect match between the be knife and the reel blades.
The reel must run in a reverse direction to be backlapped.
1. Make sure to adjust the reel to the bed knife so that
the reel is level with the bed knife and light contact
is maintained.
2. Remove the Right Side Guard (24, Fig. A).
3. Raise the mower up off the ground until the rear
roller clears the ground as shown in Figure D.
4. Loosen Hex Nut (25, Fig. C) on the back lap
assembly, pivot assembly rearward and tighten hex
nut as shown in Figure D.
5. Start engine and run at half throttle. Engage drive
clutch.
6. With reel running, apply lapping compound to the
reel with a 2” or 3” brush. Apply compound evenly to
the moving blades.
Be extremely careful not to let the brush, your
fingers or your clothing get caught in the reel.
Use approved safety glasses and gloves to
protect you from flying particles and abrasives.
Many types of compounds are available for lapping.
We recommend a good pre-mixed water soluble com-
pound. Pre-mixed compound saves time required to mix,
eliminates abrasive waste, rinses off with water and is
available In all grit ranges from course to fine.
7. Stop the reel and examine both the bed knife and
reel blades to see that the cutting edges uniformly
sharp. If not, gradually tighten reel adjuster bolts
(see Reel To Bed Knife Adjustment) and then
repeat Step 6 above until achieving the proper
sharpness.
8. Rinse off the compound thoroughly with water to
remove all abrasive.
9. Loosen the hex nut on the backlap assembly and
pivot assembly forward to disengage rear roller.
Tighten nut in the position shown in Figure E.
10. Lower machine to the ground and replace right side
guard.