MODEL 68 SR TRIPLEX MOWER
MODEL 68 DL TRIPLEX MOWER
OWNER'S MANUAL
Includes Operation, Maintenance and Parts List
NATIONAL MOWER CO.
June 2003
700 Raymond Ave., P.O. Box 14299
St. Paul, Minnesota 55114-0299, U.S.A.
Phone (651) 646-4079 – Fax (651) 646-2887
www.nationalmower.com
Page 2
ONE YEAR LIMITED WARRANTY
For the period of one year from the date of purchase (45 days if the product is used for rental purposes),
National Mower Company will repair or replace free of charge, for the original purchaser, any part or
parts found by inspection to be defective by our Factory Authorized Service Station or by the Factory
at St. Paul, Minnesota to be defective in material or workmanship or both. All transportation charges
on parts submitted for repair or replacement under this warranty shall be paid for by the purchaser.
This warranty does not include engines, engine parts or tires which are covered under separate
warranties furnished by their manufacturer or supplier. All service under this warranty will be furnished
and performed by our Factory Authorized Service Stations.
THERE IS NO OTHER WARRANTY EXPRESSED OR IMPLIED
Warranties, including those of merchantability and fitness for a particular purpose, are limited to
one year from purchase or 45 days if the product is rented, and to the extent permitted by law, any
and all implied warranties are excluded. The above remedy of repair and replacement of defective
parts is the purchaser's exclusive remedy for any defect, malfunction, or breach of warranty.
Liability for incidental or consequential damages under any and all warranties is excluded to the
extent permitted by law.
Parts Ordering Information ..................................................................... 53
Declaration of Conformity....................................................................... 55
NATIONAL 68 SR & DL TRIPLEX
®
INTRODUCTION
This manual has been prepared by National Mower
Company as an aid to users in the assembly, safe
operation, maintenance, adjustment and ordering replacement parts. Additional information will gladly be
furnished by calling or writing the manufacturer or his
authorized agent.
Please furnish us with the Model Number, Serial Number
and Date of Purchase when contacting us about your
machine. Designations of right, left, front add rear are
used as if the operator was sitting in the mower seat.
68OM-06/03
Before operating mower, carefully and completely read
this manual. The contents provide you with an
understanding of safety instructions and controls during
normal operation and maintenance. Understand all
safety precautions provided in the manuals. Review
control functions and operation of the mower. Do not
operate the mower unless all controls function as
described in this manual. Review recommended
lubrication, maintenance, and adjustments.
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SAFETY INFORMATION
The safety alert words below are used in this manual to
identify potentially hazardous conditions. Their
definitions are:
DANGERmeans "IMMINENTLY HAZARDOUS
SITUATION! If not avoided, WILL RESULT in death or
serious injury."
WARNINGmeans "POTENTIALLY HAZARDOUS
SITUATION! If not avoided, COULD RESULT in death or
injury."
CAUTIONmeans "POTENTIALLY HAZARDOUS
SITUATION! If not avoided, MAY RESULT in minor or
moderate injury." It may also be used to alert against
unsafe practices.
The safety alert triangle symbols on your mower point
out important safety precautions.
These symbols mean:
ATTENTION!
PERSONAL SAFETY IS INVOLVED!
BECOME ALERT!
OBEY THE MESSAGE!
safety guards are in place at all times, except during
servicing.
Keep all nuts, bolts, and screws tight.
3. OPERATION
Wear approved safety glasses or goggles when operating
the mower.
Do not allow children to operate mower. Do not allow
adults to operate mower without proper instruction.
Do not carry passengers. Keep children and pets at a safe
distance from an operating mower. Stop the mower if
anyone approaches the mower.
Disengage all cutting-unit clutches and shift into neutral
before attempting to start the engine. Disengage main
clutch before shifting cutting-unit clutches.
Disengage power to the cutting units and stop the engine
before leaving the operator’s position.
Disengage power to the cutting units and stop the engine
before making any repairs or adjustments.
Disengage power to the cutting units when transporting or
not in use.
Take all possible precautions when leaving the mower
unattended, including shifting into neutral, setting the
parking brake, stopping the engine and removing the
ignition key.
Watch for dangerous traffic when crossing or near roadways.
NATIONAL MOWER SAFE OPERATING
PRACTICES
1. TRAINING
Know the control functions and how to stop quickly. READ
THE OWNER’S MANUAL.
2. PREPARATION
Clear the work place of objects which might be picked up
by the blades and thrown.
Handle fuel with CAUTION - it is highly flammable.
• Use an approved fuel container.
• Never remove the fuel tank cap or add fuel to a running
or hot engine. Never fill the fuel tank indoors. Wipe up
spilled fuel immediately.
• Open garage doors to allow ventilation if engine is run
inside – exhaust fumes are dangerous. Do not run engine in any enclosed area.
Keep the mower in safe operating condition. Make sure
that all safety switches are operating properly and all
Never direct the discharge of material from operating reels
toward bystanders nor allow anyone near the mower.
The mower and reels should be stopped and inspected
for damage after striking a foreign object. The damage
should be repaired before restarting and operating the
mower.
Proceed as follows when mowing:
• Mow only in daylight or in good artificial light.
• Never make a cutting height adjustment while the engine is running.
• Shut the engine off when removing grass or unclogging
reels.
This machine is to be used only as a grass cutter or lawn
mower.
Never operate the mower while using drugs, medications,
or alcohol. Safe operation requires complete and unimpaired attention. Never allow anyone to operate the
mower when their alertness or coordination is impaired.
Do not wear loose clothing or loose shoelaces, which may
become entangled in mower controls or drive components.
4
68OM-06/03
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NATIONAL 68 SR & DL TRIPLEX
®
Do not mow in reverse, unless absolutely necessary.
Always look down and behind before and during reverse
motion.
Shut off and raise the cutting units before operating the
mower at transport speed. (Model 68 DL only.)
Do not reverse battery connections. Damage to the mower
can result. Battery gases are explosive and can cause
death or injury. Keep open flames, sparks, and smoking
materials away from batteries. Battery fluid contains
sulfuric acid. Contact with skin, eyes, or clothing can
cause chemical burns. Wash immediately and seek
medical assistance. Wear protective clothing and safety
glasses when handling a battery. (Model 68 DL only.)
4. HILL OPERATION
Do not stop or start suddenly when going uphill or downhill.
Mow up and down the face of steep slopes — never across
steep slopes. Do not exceed a slope of 15o in any direction.
Reduce travel speed on slopes and in sharp turns to
prevent tipping or loss of control. Use extreme caution
when changing direction on slopes.
Watch for holes in the terrain and other hidden hazards.
Do not shift into neutral and coast downhill.
Use extreme care when mowing near dropoffs or embank-
ments. The mower could roll over if a wheel goes over the
edge, or if an edge caves in.
If mower stops going uphill, disengage power to the cutting
units and slowly back down.
5. MAINTENANCE
Never store the mower, with fuel in the tank, inside a
building where fumes could reach an open flame or spark.
Allow the engine to cool before storing in any enclosure.
Keep the engine free of grass, leaves or excessive grease
to reduce a fire hazard.
Do not change the engine governor settings or overspeed
the engine.
Keep non-skid surfaces clean. Replace the non-skid
material if worn, damaged, or missing.
Never mow while people, especially children, or pets are
nearby.
Keep in mind that the operator or user is responsible for
accidents or hazards occurring to other people or their
property.
Do not carry passengers.
All drivers should seek and obtain professional and
practical instruction. Such instruction should emphasize:
• the need for care and concentration when working with
ride-on machines;
• control of a ride-on machine sliding on a slope will not
be regained by the application of the brake. The main
reasons for loss of control are:
• insufficient wheel grip;
• being driven too fast;
• inadequate braking;
• the type of machine is unsuitable for the task: do not
use mower for unsuitable tasks;
• lack of awareness of the effect of ground conditions,
especally slopes;
• hitching and load distribution: do not hitch or tow
other devices.
2. PREPARATION
WARNING
Gasoline (petrol) is highly flammable.
Store fuel in containers specifically
designed for this purpose. Refuel outdoors only. Do
not smoke while refuelling. Add fuel before starting
the engine. Never remove the cap of the fuel tank or
add fuel while the engine is running or when the engine
is hot. If fuel is spilled, do not attempt to start the
engine but move the machine away from the area of
spillage and avoid creating any sources of ignition
until fuel vapors have dissipated. Replace all fuel
tanks and container caps securely.
While mowing, always wear substantial footwear and
long trousers. Do not operate the equipment when
barefoot or wearing open sandals.
Wear appropriate safety gear, including safety glasses
and gloves, while servicing the mower.
ISO SAFE OPERATING PRACTICES
1. TRAINING
Read the instructions carefully. Be familiar with the
controls and the proper use of the equipment.
Never allow children or people unfamiliar with these
instructions to use the lawnmower. Local regulations can
restrict the age of the operator.
68OM-06/03
Thoroughly inspect the area where the equipment is to be
used and remove all objects which can be thrown by the
machine.
Replace faulty silencers.
Before using, always visually inspect to see that the reels,
bed knives, and cutting unit assemblies are not worn or
damaged. Replace worn or damaged reels and bedknives
in sets to preserve balance.
On multi-reel machines, take care as rotating one reel can
cause other reels to rotate.
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SAFETY INFORMATION
3. OPERATION
Do not operate the engine in a confined space where
dangerous carbon monoxide fumes can collect.
Mow only in daylight or good artificial light.
Before attempting to start the engine, disengage all cutting
unit clutches and shift into neutral.
Do not use on slopes of more than 15°.
Remember there is no such thing as a safe slope. Travel
on grass slopes requires particular care. To guard against
overturning:
• do not stop or start suddenly when going up or downhill;
• engage clutch slowly , always keep machine in gear, especially when travelling downhill;
• machine speeds should be kept low on slopes and during tight turns;
• stay alert for humps and hollows and other hidden hazards;
• never mow across the face of the slope, unless the machine is designed for this purpose.
Watch out for traffic when crossing or near roadways.
Stop the reel rotation before crossing surfaces other than
grass.
Never direct discharge of material toward bystanders or
allow anyone near the machine while in operation.
Never operate the lawnmower with defective guards, or
without safety devices in place.
Do not change the engine governor setting or overspeed
the engine. Operating the engine at excessive speed can
increase the hazard of personal injury.
Before leaving the operator's position,
• disengage the power take-off and lower the cutting units;
Disengage drive to attachments when transporting or not
in use.
Stop the engine and disengage drive to attachment:
• before refuelling;
• before removing the grass catcher;
• before making height adjustment;
• before cleaning blockages;
• before checking, cleaning, or working on the mower;
• after striking a foreign object. Inspect the mower for
damage and make repairs before restarting and operating the equipment.
Reduce the throttle setting during engine shutdown and
turn the fuel off at the conclusion of mowing.
4. MAINTENANCE AND STORAGE
Keep all nuts, bolts, and screws tight to be sure the
equipment is in safe working condition.
Never store the equipment with fuel in the tank inside a
building where fumes can reach an open flame or spark.
Allow the engine to cool before storing in any enclosure.
To reduce the fire hazard, keep the engine, silencer,
battery compartment, and fuel storage area free of grass,
leaves, or excessive grease.
Replace worn or damaged parts for safety.
If the fuel tank has to be drained, this should be done
outdoors.
When machine is to be parked, stored, or left unattended,
lower the cutting means unless a positive mechanical
lock is used.
Be careful during adjustment of the machine to prevent
entrapment of the fingers between moving blades and
fixed parts of the machine.
• shift into neutral and set the parking brake;
• stop the engine and remove the key.
Disengage drive to the cutting units, stop the engine,
remove the ignition key, and disconnect the spark plug
wire:
• before cleaning blockages or unclogging chute;
• before checking, cleaning, or working on the machine;
• after striking a foreign object. Inspect the lawn mower
for damage and make repairs before restarting and operation the lawn mower;
• if lawn mower starts to vibrate abnormally (check immediately).
6
On multi-reel machines, take care as rotating one reel can
cause other reels to rotate.
CALIFORNIA SAFE OPERATING PRACTICES
Mowers used in California, USA are required by law (CA
PRC 4442 & CA H & SC 13005) to have their engines
equipped with spark arresters when operating in flammable vegetation. Arresters must be obtained from your
engine dealer and are not available from National Mower
Company.
68OM-06/03
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NATIONAL 68 SR & DL TRIPLEX
®
SAFETY AND CONTROL DECALS
Safety decals and instructions are located on the mower near the controls or near areas of potential hazards. Worn,
damaged, or loose decals must be replaced. The decal part number and the location of the decal on the mower are
listed next to each decal.
07581 - MAIN ENGINE CLUTCH
LEVER
(located on top surface of engine
belt guard)
Move lever backward to put
clutch in neutral position, forward
to cause mower to travel
(direction depends on differential
shift position).
WARNING
07582 - DIFFERENTIAL SHIFT LEVER
(located on top edge of differential gear drive)
Move the shift lever and set it in the notch to place the
differential into Forward, Neutral, or Reverse. NEVER
SHIFT THE DIFFERENTIAL WITH THE MOWER IN
MOTION OR THE MAIN ENGINE CLUTCH ENGAGED.
Engage the clutch slowly. Refer to
instructions in the OPERATIONS section
07584 – TRANSPORT CLUTCH PEDAL
(Model 68 DL)
(located on top surface of engine belt guard)
Pressing the pedal will cause the mower to
run in high-speed transport mode. Operate
the transport clutch by slowly pressing the
pedal with your left foot. Releasing the
pedal will cause the mower to coast to a
stop, or resume mowing speed.
Before using, disengage the cutting unit
clutches and raise the cutting units to their
transport position.
WARNING
UNITS ARE TURNING, OR WHEN THE DIFFERENTIAL SHIFT IS IN REVERSE.
NEVER USE THE TRANSPORT
CLUTCH WHILE THE CUTTING
07585 – ENGINE THROTTLE
(located on steering wheel)
Move the engine throttle lever forward
for fast speed, backward for slow speed
68OM-06/03
07583 – WING MOWER CLUTCH
(located on top surface of main belt
guard)
Move the clutch lever back to engage
the wing mower clutch. Move the lever
forward to put the clutch in neutral.
To start the engine, sit on the seat and
place all cutting unit clutches in neutral.
Turn the key to the full clockwise position
to start the engine. Use the choke as
required. Once the engine has started,
release the key and allow it to rotate to the
central run position.
To stop the engine, turn the key to the full
counterclockwise position.
Refer to the engine manual for details on proper engine
operation.
Disengage cutting unit clutches, engage the parking brake
and remove the key whenever leaving the mower seat.
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SAFETY AND CONTROL DECALS
07587 – IGNITION KEY (Model 68 SR)
(located on top surface of main belt
guard)
To start the engine, place the main
clutch and all cutting unit clutches in
neutral. Turn the key to the clockwise
position and pull on the recoil starter.
Use the choke as required.
To stop the engine, turn the key to the
full counterclockwise position.
Refer to the engine manual for details on proper engine
operation.
Disengage cutting unit clutches, engage the parking
brake and remove the key whenever leaving the mower
seat.
07588 – PARKING BRAKE LEVER
(located on top surface of main belt
guard)
07599 – WARNING
DECAL
(located on instrument
cluster [68 DL] or main
belt guard [68 SR])
Read and understand
the information in the
Owner’s Manual before operating this
mower.
Read and understand
the information in the
Owner’s Manual
before attempting to
repair, service, or
maintain this mower.
Turn off the mower
engine, remove the
ignition key, and
disconnect the engine
spark plug before
attempting to repair, service, or maintain this mower.
Move the parking brake lever
forward to set the brake, rearward
to release the brake. Driving the
mower with the parking brake set
will cause excess wear on the brake
mechanism.
07589 – SERVICE BRAKE PEDAL
(located on top surface of main belt
guard)
Press the brake pedal with your right
foot to stop the mower. You must also release the main
engine clutch in order for the mower to come to a
complete stop.
WARNING
the state of California to cause cancer, birth defects, or
other reproductive harm. Do not operate the engine in
a confined space where dangerous carbon monoxide
fumes can collect.
WARNING
DANGER
engaged. Serious injury or death can result from loss
of control.
WARNING
The engine exhaust from this product contains chemicals known to
Objects may be thrown from the cutting units. Keep bystanders away
from the mower.
Never allow the mower to freewheel
down hills without the traction drive
Do not operate the mower on slopes
greater than 15 degrees.
8
68OM-06/03
Page 9
07590 – REAR CUTTING UNIT CLUTCH
(located on top surface of rear cutting unit)
Pull lever forward and toward the center of the machine
to engage sliding jaw clutch.
To disengage, pull lever forward and out to engage
locking pin.
Never engage the drive unless the rear cutting unit has
been lowered to the cutting position.
(Note that the decal is viewed properly while looking
toward the rear of the mower.)
NATIONAL 68 SR & DL TRIPLEX
®
07083 – SERIAL NUMBER DATA PLATE
(located on mower frame, left side, below seat)
07595 – MANUFACTURER & SOUND LEVELS
(located on left side of main belt guard)
Guaranteed sound power level and manufacturer’s
information
07415 – MODEL 68 DL LABEL (68 DL only)
07598 – MODEL 68 SR LABEL (68 SR only
(located on left side of engine belt guard and right side of
main belt guard)
07600 – CUTTING UNIT DANGER
(located on top surface of each cutting unit)
DANGER
Reels and bed knives on the cutting
units are sharp. Keep hands and
feet away from the cutting units.
DANGER
Do not attempt to work around the
cutting units while they are running.
Your fingers, hands, arms, or any loose clothing may
become entangled in the belt drives. Do not operate
the cutting units unless you are seated on the mower.
Keep all guards and shields in place.
205341 – INSTRUCTIONS for OPTIONAL DIAL-AHEIGHT ADJUSTER
(located on the top shield of each cutting unit)
Raise and turn the adjuster knob counterclockwise to
lower the height of cut. Raise and turn the adjuster knob
clockwise to raise the height of cut. Read the instructions
for the Dial-A-Height adjusters in the Operations section
of this manual.
Align the bottom edge of the Dial-A-Height bracket with
the desired height of cut on this decal. Read the instructions
for the Dial-A-Height adjusters in the Operations section
of this manual.
10
68OM-06/03
Page 11
RECEIPT OF SHIPMENT
NATIONAL 68 SR & DL TRIPLEX
®
Carefully inspect your machine and crate for damage that
could have occurred during shipment. If damages or
shortages are noted, have the transportation company’s
representative note this on the bill of lading.
UNCRATING INSTRUCTIONS
CAUTION
In order to prevent possible damage to the machine or
personal injury, the following uncrating procedure must
be followed:
1. Position Crate (1) on a hard, level surface.
2 Cut and remove all Steel Banding (2). Remove the
entire top of the crate.
Wear protective gloves. Steel
banding is sharp. Handle cutting
units carefully. Reels rotate freely
and are very sharp.
Note: Claims for shipping damages must be noted by the
consignee at the point of destination and filed with the
transportation company that delivers the shipment.
3. Unbolt Seat (3) from crate bracing and lay seat aside
for installation later.
4. Lift Rear Cutting Unit (4) off the crate supporting
members and set aside for later attachment.
5. Make sure Wing Cutting Units (5) are in their upright
positions, secured to the mower frame with Wing
Cutting Unit Latches.
6. Knock down all sides of crate and remove. Roll
mower backwards off of crate base.
CAUTION
CAUTION
68OM-06/03
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ASSEMBLY
WARNING
Improper assembly or adjustments
can cause serious injury.
SEAT
1. Mount the Rear Cutting Unit Lifter and Seat Assembly
(A) to the mower frame using (2) 1/2" bolts, nuts, and
washers (B).
2. Fasten the seat slides (C) to the bottom of the seat (D)
using the fasteners provided with the slider mechanisms. Orient the slider so the adjuster lever (E) is on
the operator's left hand side.
3. Remove the seat switch bracket (F, 1" x 10" bar))
mounted near the ends of the legs of the seat hinge.
Discard the fasteners. Mount the seat and slider assembly onto the seat hinge (G). Replace the seat
switch bracket and tighten fasteners. Plug the wire
harness socket (H) into the seat safety switch (J). Use
care in routing the wires so that they are not pinched
by the switch lever or seat support mechanisms.
12
REAR CUTTING UNIT
1. Pivot the Seat Brace (A) from the axle so that the top
end aligns with the tab at the back of the seat hinge
assembly. Fasten with a 5/16" x 1" Hex Head Bolt,
Lock Washer and Hex Nut.
2. Slide the rod end of the lifter tee (B) through the hole
(C) in the pad on the rear mower frame and secure it
to the lift arm pivot with the cotter pin and washer as
shown at (D).
3. Attach the Pull Rod (E) to the cutting unit Pivot Tube
(F) with Pin and Spacers.
NOTE: Before completing assembly, it will be necessary
to adjust the drive belt tension. See "Rear Cutting Unit
Drive Belt Tension" in the Maintenance section of this
manual, page 23.
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Page 13
NATIONAL 68 SR & DL TRIPLEX
®
WING CUTTING UNITS
1. Remove the two Wing Cutting Unit Belts from the
steering column.
2. Release the Laches (A) from Wing Cutting Units. To
release the latch, lift the wing cutting unit handle until
the latch swings upward into a nearly vertical position.
Carefully lower the cutting unit to the ground. Avoid
dropping the cutting unit, as damage may result to the
cutting unit, the mower, or your turf.
3. Slip wing Cutting Unit belts (B) over Countershaft
Pulleys (C).
4. Block mower wheels to prevent mower from moving
forward. Pull Wing Cutting Units (D) forward so that
they slide on Pull Rods (E) and compress springs (F).
This will allow enough slack to enable belts to be
installed over Reel Pulleys (G).
5. Pull Cutting Units backwards to adjust belt tension.
Tighten bolt (H) to lock in place.
REAR CUTTING UNIT BELT
Install Rear Cutting Unit Belt (A) from Countershaft Pulley
(B) to outer Drive Pulley (C). Idler Pulley (D) must ride on
top of lower belt to provide proper tension. NOTE: It will be
necessary to raise rear cutting unit to allow enough slack
to get belt over pulleys.
REEL TO BED KNIFE ADJUSTMENT
To prevent damage during shipment, the reels have been
moved away from the bed knives at the factory. Follow
the procedure for "Reel to Bed Knife Adjustment" in the
Maintenance section of this manual to properly adjust
your cutting units.
ENGINE
CAUTION
MOWER IS SHIPPED WITH DRY
ENGINE. DO NOT START ENGINE
UNTIL OIL IS ADDED TO CRANKCASE. See Engine
Manual for additional information.
DIFFERENTIAL
Grease has been installed in the differential at the factory.
For additional information, refer to the Maintenance section of this manual.
68OM-06/03
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PREPARATION
DANGER
knives are very sharp. Reels rotate freely and rotating
one reel can cause other reels to rotate.
CAUTION
safe operating suggestions listed in the Safety Information
section of this manual.
Check the following items before each use of the mower.
TIRE PRESSURE - Use a tire pressure gage to check
the tire pressure. Fill tires with compressed air as
needed to obtain the pressure labelled on the sidewall of
the tire.
ENGINE OIL - Check level on dipstick. Refer to the
engine manual for instructions on adding oil and which
oil viscosity to use.
Handle cutting units carefully with
protective gloves. Reels and bed
Moving machinery can be dangerous
if not operated properly. Follow all
FUEL - Check fuel level. Add fuel as required. Refer to
the engine manual for type of fuel and other safety
requirements.
ENGINE COOLING - Keep engine cowlings clear of
clippings.
LUBRICATION - Add lubricant to pivots and other
lubrication points as required. Refer to the lubrication
chart in the Maintenance section of this manual.
REELS CLEAR OF DEBRIS - Remove any debris that
may be tangled in the cutting reels. Keep the reel shaft
and bearing clean of grass or other debris buildup.
SAFETY SWITCH OPERATION - Check operation of all
safety switches. Do not use mower if safety switches are
disconnected or not operational, as dangerous conditions
will result.
OPERATION
The following is a description of the machine controls
and their function.
A. Main Clutch Lever
WARNING
the drive when stopping or leaving the machine.
Engage slowly before full
engagement. Always disengage
Engages power for
travel and mowing. Down
position is disengaged
and up position is
engaged.
The engine clutch lever has an electrical interlock and
engine will not start if clutch is engaged. For added
safety, the interlock system should be checked
periodically to ensure that it is adjusted to function
properly.
B. Engine Throttle Lever – Regulates mowing and
travel speeds. Moving the control handle back will reduce
engine speed for starting and idling engine. Push forward
to increase engine speed. Never travel at speeds faster
than required for proper mowing.
C. Wing Cutting Unit Clutch Lever – Engages drive to
Wing Cutting Units. Pull lever back and down to engage.
Never engage drive unless Wing Cutting Units have
been lowered to cutting position.
Engine Choke Lever (No photo) - Located near the
upper rear right corner of the engine. Use the choke
when starting a cold engine. See the engine manual for
engine starting information and proper use of the choke.
14
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Page 15
OPERATION
NATIONAL 68 SR & DL TRIPLEX
®
D. Transport Clutch (Model 68 DL only)
WARNING
UNITS ARE TURNING OR WHEN THE
DIFFERENTIAL SHIFT IS IN REVERSE.
Operate the transport clutch by slowly pressing the pedal
with your left foot. Releasing the pedal will cause the
mower to coast to a stop, or resume mowing speed.
E.Wing Cutting Unit Latch
NEVER USE THE TRANSPORT
CLUTCH WHILE THE CUTTING
Use this clutch to travel
between mowing sites at
speeds faster than those
obtained with the main
clutch. Before using,
disengage the cutting unit
clutches and raise the
cutting units to their
transport position.
G. Rear Cutting Unit Clutch
Engages drive to the Rear
Cutting Unit.
Pull lever forward and
toward the center of the
machine to engage sliding
jaw clutch.
To disengage, pull lever
forward and out to engage
locking pin.
Never engage the drive
unless the rear cutting unit
has been lowered to the
cutting position.
H. Rear Cutting Unit Lift Arm
Raises rear mower to the
transport position. Pull
handle up, forward and
over center to lock it in
the up position.
WARNING
The Wing Cutting Units should be latched in their elevated
position whenever the mower is being transported or in
storage.
To release the latch, lift the handle until the latch (E)
swings upward into a nearly vertical position, then carefully
lower the cutting unit onto the ground. Avoid dropping the
cutting unit, as damage may result to the cutting unit, the
mower, or your turf.
NEVER ATTEMPT TO RAISE THE
WING CUTTING UNITS WHEN
THE WING MOWER CLUTCH IS
ENGAGED.
If needed, push the latch
(E) down to a generally
horizontal position. Grasp
the Wing Cutting Unit lift
handle (not shown) and
raise the cutting unit until
the latch (E) engages the
lift arm socket (F).
J. Seat Position Adjuster Lever
WARNING
The seat may be moved forward or backward to suit the
operator. Pull the lever near the front left corner of the
seat outward to release the slide mechanism. After
moving the seat to a comfortable position, release the
lever to lock the slide mechanism.
.
DO NOT OPERATE THE SEAT
SLIDE MECHANISM WHILE THE
MOWER IS MOVING
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Page 16
OPERATION
K. Ignition Switch (Model 68 DL shown)
CAUTION
engine. Turn the switch counterclockwise to shut off the
engine.
The 68 SR ignition switch (not shown) is located on the
steering column. It is a two-position switch.
Turn the key clockwise to activate the electrical system
and allow the engine to be started. Turn the switch
counterclockwise to shut off the engine.
ALWAYS SHUT OFF THE ENGINE
AND REMOVE THE KEY BEFORE
LEAVING THE MOWER SEAT.
The 68 DL ignition
switch is located on
the instrument
cluster. It is a threeposition switch.
Turn the key
clockwise to the
middle position to
activate the electrical
system. Turn the key
to the full clockwise
position to start the
M. Parking Brake Lever
Provides a lock for the brake. Push brake lever forward,
over center, to lock. Pulling brake lever back, toward the
rear of the machine will disengage the brake.
N. Service
Brake
Depress the Service Brake foot
pedal to slow the
mower and lock
the rear wheels
in the full stop
position.
Note: It is best to
slow the mower
with the throttle and then disengage clutch lever before
applying brake. This prevents excessive wear and engine
overload.
SAFETY SWITCHES
L. Differential Shift Lever
WARNING
result. Always disengage engine clutch before attempting to shift.
ter of the machine to clear the notch in the stop disc and
positioned securely in the new notch.
Never shift while machine is in motion, as damage to the gears could
Located on
the mower
differential,
this control
has three positions: Forward, Neutral (center
position),
and Reverse. The
lever must be
pulled toward the cen-
Your National 68 mower is equipped with safety switches
to monitor the operating conditions of certain machine
functions and stop the mower whenever unsafe conditions
are found.
It is necessary for both the main engine clutch and the
wing cutting unit clutch to be in their neutral position to
start the engine. The 68 DL also requires the operator be
in the seat. The 68 SR does not require the operator to be
in the seat to facilitate use of the hand recoil starter.
If you encounter difficulties starting the mower’s engine,
or keeping it running, check the chart in the Safety
Switches section of this manual to make sure you are not
causing the engine to kill or become unable to start.
16
68OM-06/03
Page 17
NATIONAL 68 SR & DL TRIPLEX
®
HEIGHT OF CUT ADJUSTMENT
DANGER
ignition key, and disconnect the engine spark plug
wire prior to making any of the following adjustments.
1. STANDARD ADJUSTERS
The height of cut is variable and may be adjusted on both
wing cutting units and the rear cutting unit by loosening
the top and bottom Adjusting Nuts (A) which hold Roller
Adjusters (B) in Roller Brackets (C). Roller (D) may then
be moved up and down.
It is important to get all rollers adjusted to the same height
so that there will be uniform cutting across the entire width
of the cutting unit. Do not adjust by sight. Place the mower
on a hard, level surface and place a board or gauge plate
of the desired height under each bed knife back bar. Allow
the rear roller to rest on the level surface. Retighten the
adjusting nuts and remove the gauge plate or board.
To assure safety, disengage the
engine clutch lever, remove the
2. DIAL-A-HEIGHT ADJUSTERS (OPTIONAL)
To set the height of cut, lift the vinyl cap and socket (A) off
the adjuster tube. To raise the height of cut, turn the
socket clockwise (viewed from above). To lower the
height of cut, turn the socket counterclockwise. Each
quarter turn (90°) of the socket will raise or lower the
height of cut by approximately 1/32". A full turn (360°) will
raise or lower the height of cut approximately 1/8".
When making large adjustments (over 1/2"), make small
adjustments to each side until the desired change is
reached. When the desired height is achieved, lower the
socket and make sure the adjuster tube locks it in position.
The scale decal (C) on the rear side of the adjuster
indicates the height of cut. To use it, sight along the
bottom edge of the adjuster tube (B). The reading on the
scale is your approximate height of cut.
You should determine the exact settings by test mowing
your turf. If very accurate cutting heights are required,
place the cutting units on a hard, level surface and place
a board or other gauge plate of the desired height under
each bed knife backing bar. Lower the rollers to the level
surface. When completed, make sure the socket is
locked in position over the adjuster tube.
STANDARD HEIGHT ADJUSTER
NOTE: Guards removed or cut away to show detail
68OM-06/03
DIAL-A-HEIGHT ADJUSTER (OPTIONAL)
OTHER ADJUSTMENTS
For other machine adjustments, see the Maintenance
section of this manual.
17
Page 18
MAINTENANCE
LUBRICATION
Lubricate the machine at the recommended locations and
intervals using the proper lubricants to ensure maximum
service and long life of your machine.
Lubrication locations must be free of dirt and grass
clippings and be well lubricated for proper operation.
The location and number of all lubricating points are listed
in the chart below. The type and frequency of lubrication
is specified. Use the following photos to locate the
lubrication points on the mower.
DIFFERENTIAL
Since the mower does not operate at high speeds, the
grease level in the differential is not critical providing that
there is sufficient grease to coat the gears. Unless
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leakage is evident, it is recommended that the grease be
checked once each year. Check grease level by loosening
the bolts in the differential case flanges and spreading
case halves. It is not necessary to totally disassemble the
case or remove the wheels for this inspection. Add Multipurpose Gear Grease such as Pennzoil No. 303 or
equivalent if necessary. Total grease capacity is 1-1/2
pounds (0.68 kg).
CAUTION
Do not use oil in the differential case
in place of grease–it will leak through
the seals.
ENGINE
Refer to the engine manual (separately furnished) for
ignition key, and disconnect the engine spark plug
wire prior to making any of the following adjustments.
DANGER
very sharp. Reels rotate freely and rotating one reel
can cause other reels to rotate. Special care should be
taken in the area where the reel contacts the bed knife.
REEL TO BED KNIFE ADJUSTMENT
The reel is adjusted to a fixed position bed knife. This
construction allows a more rugged and durable frame and
retains the proper adjustment longer. The Reel Adjuster
Bolt (A) regulates reel distance from the bed knife.
To reduce the distance, turn the upper hex adjuster nut on
each side of the reel down. Proceed slowly and do not
over-adjust -- use about 1/8 of a turn on each side at first.
To assure safety, disengage the
engine clutch lever, remove the
Handle reel assemblies carefully
with protective gloves. Reels are
Do not adjust one side more than the other unless the reel
is obviously out of alignment. Do not get the reel so tight
that it is hard to turn by hand. A too tight reel will wear
faster.
Ideally, the reel should “wipe” or lightly touch the bed
knife. It is not necessary to adjust or change the position
of the lower adjustment nut.
Proper cutting action may be tested by holding paper
strips between the reel and the bed knife. Turn the reel by
hand and check to see if the assembly cuts the paper all
the way across the width of the bed knife. Make sure that
the adjusting and the locking nuts on both side are
tightened securely.
REEL END PLAY ADJUSTMENT
Test for end play periodically by trying to move the reel
from side to side in the frame. If there is ANY movement,
adjust the bearings by loosening the lock nut on the
adjustment bolt (B) which is located on the inside right end
of the reels, and turning the adjustment bolt IN one half
turn or less. Do not overtighten. An overtightened bearing
will cause excessive bearing wear. Test again for end
play and if reel is rotating freely and end play is not
noticeable, tighten the lock nut.
REEL ADJUSTMENTS
HEIGHT OF CUT ADJUSTMENT
Refer to "Height of Cut Adjustment" in the Operation
section of this manual.
BRAKE ADJUSTMENT
The foot brake is properly adjusted if it slows the machine
when depressed and can be locked when the pedal is
depressed fully.
Adjust brake tension by removing cotter pin and brake
pedal pin and turning brake clevis located under pedal on
brake rod. When adjustment is complete, attach clevis to
pedal with pin and cotter pin.
NOTE: Guards removed or cut away to show detail
22
68OM-06/03
Page 23
ADJUSTING DRIVE BELT TENSION
A belt adjusted for proper tension can be deflected slightly
at a point midway between the pulleys. An over-tight belt
will cause excessive bearing wear and an under-tight belt
allows slipping, causing excessive belt wear.
IMPORTANT: Never allow oil to get on the belt which
could cause slipping.
NATIONAL 68 SR & DL TRIPLEX
®
WING CUTTING UNIT DRIVE BELT TENSION
Adjust tension by loosening set screw (B) in the wing
mower pull arm, sliding the Cutting Unit rearward and
retightening set screw.
MAIN DRIVE BELT TENSION (Main Countershaft to
Rear Drive)
Belt tension is increased by loosening the four bolts
holding the Upper Countershaft Housing (A) and sliding
the housing forward in the slotted frame holes.
NOTE - It will be necessary to remove belt guards to reach
the adjustment bolts. Also, if this belt is adjusted, it will be
necessary to readjust the engine belt. Replace all belt
guards before using the mower.
ENGINE DRIVE BELT TENSION (Engine to Main
Countershaft) (No photo)
Belt tension is increased by loosening the four engine
mounting bolts and sliding the engine forward in the
slotted frame holes. Test for the proper tension as detailed
in the section "Wing Cutting Unit Drive Belt Tension".
When tension is correct, tighten all the bolts securely.
FRONT
OF
MACHINE
REAR CUTTING UNIT DRIVE BELT TENSION
Spacers (A) are provided on the rear mower Pull Rod (B)
to adjust the belt tension. Remove Pin (C) from the end of
the pull rod and slip out the pull rod from the Pivot Tube
(D). Move as many spacers as necessary to the location
indicated and reassemble.
68OM-06/03
23
Page 24
MAINTENANCE
REAR CUTTING UNIT CHAIN TENSION
A chain drive is located on the left side of the rear cutting
unit. It maybe helpful to remove the Chain Shield (A) prior
to adjusting the chain tension.
Adjust the tension of the chain by loosening the 4 bolts (B)
on the rear cutting unit countershaft housing. Rotate the
countershaft housing (C) about the pivot line created by
the fixed bolts. The slots on the countershaft housing will
slide over the remaining two bolts. Rotate the countershaft
housing until proper chain tension is achieved. Tighten
bolts.
Proper tension is achieved when the chain is slightly
loose, but does not deflect more than 1/2" when pressed
in the middle of the span between the two sprockets.
BED KNIFE REPLACEMENT
DANGER
When the bed knife becomes damaged or too worn to
keep sharp, it must be replaced. Follow the procedure
below.
1. The backbar (A), bed knife (B) and fasteners (C,D) have
been assembled at the factory under tension. To ease
replacement and prevent misalignment of components, you may wish to clamp the leading edge of the
backbar in two or three places before removing the old
fasteners.
2. Remove the old shoulder nuts (C) and flat head screws
(D). If shoulder nuts are badly rusted or corroded, they
may have to be cut off and screws driven out to be
removed.
3. Clean the bottom surface of the backbar for maximum
metal contact with the new bed bar.
4. Fasten the new bed knife to the bottom of the backbar
in the position shown (bent edge up). Shoulder of
shoulder nuts (C) must be seated firmly in the backbar
and screws (D) must be flush with the bottom of the bed
knife.
Reels and bed knife are sharp. Wear
gloves to avoid cutting fingers on
sharp edges. Wear safety glasses
to protect eyes.
24
5. Torque shoulder nuts 35 to 40 ft-lbs.
68OM-06/03
Page 25
BACK LAPPING PROCEDURE
DANGER
Be extremely careful not to let the
brush, your fingers or your clothing
get caught in the reels. Wear gloves to avoid cutting
fingers on sharp edges. Wear approved safety glasses
to protect your eyes from flying particles and abrasives.
INTRODUCTION
Back lapping is a very important step in maintaining sharp
reel blades on the cutting units.
NATIONAL 68 SR & DL TRIPLEX
BACK GRIND IN THE
DIRECTION
OF THE ARROW
®
This procedure should be performed when the reel blades
and the bed knife become slightly rounded and the grass
is not cut cleanly with only a slight reel to bed knife
adjustment. Also, after grinding the bed knife and reels,
you should back lap to establish a perfect match between
the bed knife and reel blades.
RECOMMENDED STEPS
1. Adjust the reel to the bed knife so that the bed knife is
parallel to the reel and light contact is maintained.
2. Reels must be run in a reverse direction to be lapped.
Remove the lower drive belts and attach a back
lapping machine (not supplied by National Mower) to
the reels. Follow the instructions furnished by the
machine manufacturer.
3. Apply the lapping compound with the reels running,
using a 2" or a 3" (5 - 7.5 cm) brush. Apply the
compound evenly to the moving blades.
Many types of compounds are available for lapping. We
recommend a good pre-mixed water soluble compound.
Pre-mixed compound saves the time required to mix,
eliminates the waste of abrasive, rinses off easily with
water and is available in all grit ranges from coarse to
extra fine.
4. Stop the reel and examine both bed knife and reel
blades to see that the cutting edges are uniformly
sharp. If not, gradually tighten the reel adjuster bolts
(see "Reel to Bed Knife Adjustment" above) and
repeat Step 3 until the proper sharpness results.
O
25
Note position of
blades to reel
axis
GRINDING REELS
Reels must be ground at 25° in the direction shown by the
arrow in the figure. Back grind until reel blades are free
from roundness, dents and nicks. Spin grind to remove all
burrs. All blades must be on the same diameter.
O
5
O
5
GRINDING BED KNIVES
For maximum cutting efficiency, grind bed knife top and
front edges at 5° as shown in the figure.
5. Rinse off the compound thoroughly with water to
remove all abrasive. Check for sharpness and readjust
the bed knife if necessary. Reel to bed knife contact
should be adjusted to easily cut a sheet of paper (see
"Reel to Bed Knife Adjustment" above).
68OM-06/03
25
Page 26
MAINTENANCE RECORD
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26
68OM-06/03
Page 27
TROUBLE-SHOOTING
NATIONAL 68 SR & DL TRIPLEX
®
DANGER
All adjusting must be made with the engine off.
Do not do any investigation of the working parts of the machine with the motor running.
Always turn the engine off!
Tractor Unit
SituationThings To Check
Engine will not startTurn ignition switch to on
Ensure that there is sufficient gasoline (petrol) in the tank
Make sure safety switches are making contact and mowing clutch is in
neutral
Look for a loose wire on ignition or spark plug wire not connected
Interlock system inoperative—check wiring, see "Electrical Diagrams"
Operator must be positioned on seat to depress safety switches
(Model 68 DL only)
Mower will not moveDifferential gear selector must be in one of the drive positions
Engine drive clutch must be engaged
Drive belts too loose (see "Drive Belt Tension" in Maintenance section)
Visually check to see that pulleys are not slipping on shafts
If everything above is OK, check for a damaged gear(s) in the differential
gear box
Mower will not stopEnsure that the main clutch is disengaged (brake will not stop engine)
Brake adjustment or service may be needed.
Cutting Units
Situation
Cutting units will not turn.Clutches may not be engaged
Look for anything that could be jammed between the reel and the bed knife
Drive belts or drive chain may need tightening
Visually check that both the drive pulleys and the shafts are rotating
Cutting units turn butReel bed knife position may be out of adjustment (see "Reel to Bed Knife
will not cutAdjustment" in Maintenance section)
Drive belts or drive chain may need adjustment.
Visually check that both the drive pulleys and the shafts are rotating
Cutting units will not stopDisengage all clutches
turning
Uneven cutSet height of cut to the same height on each cutting unit (see "Cutting Height
Adjustment" in Operation section of this manual.)
Check to see if any part is bent
Something may be jammed in cutting unit pivots and/or lift pivots, preventing
the cutting units from floating
FRAME
REAR TIRE & WHEEL ASSEMBLY
FOOT REST, Left Hand
BUSHING, Axle Pivot
BUSHING, Spindle and Steering Post
DRAG LINK
KING PIN, Left Hand
TIRE & WHEEL
SHAFT, Steering
AXLE ASSEMBLY, Front
TIE ROD
PIN, Clevis Tie Rod
KING PIN, Right Hand
BUMPER, Front
BEARING, Wheel Hub
DUST CAP, 3/4'’ I.D.
DUST CAP, 7/8'’ I.D.
CLEVIS, Threaded, Tie Rod
PEDAL, Brake
FOOT REST, Right Hand
SWITCH, Interlock
GUARD, Main Belt
STEERING WHEEL
COLLAR, Steering Shaft
BRACKET, Throttle Control
SWITCH, Key, Briggs & Stratton and Kawasaki
THROTTLE CONTROL, (Includes conduit and wiring)
SEAT
BALL JOINT
SHIELD, Engine
GRIP, Lever, '96 and up
LEVER, Lower Countershaft Control
SWITCH, Control
U-NUT, 1/4-20
BRACKET, Muffler Guard, L.H.
BRACKET, Muffler Guard, R.H.
GUARD, Muffler
ROD, Countershaft Idler Control (shown for reference only)
SPRING
COLLAR, Lock
ROD
SPRING, Lift Latch
BUSHING
HOOK, Wing Mower
ROLL PIN, 0.25 x 1.12
Never attempt to remove or
circumvent the safety switches.
Dangerous operating conditions may result.
Your National 68 mower is equipped with safety switches
to monitor the operating conditions of certain machine
functions and stop the mower whenever unsafe conditions
are found.
It is necessary for both the main engine clutch and the
wing cutting unit clutch to be in their neutral position to
start the engine. The 68 DL also requires the operator be
in the seat. The 68 SR does not require the operator to be
in the seat to facilitate use of the hand recoil starter.
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If you encounter difficulties starting the mower’s engine,
or keeping it running, check the chart below to make sure
you are not causing the engine to kill or become unable
to start.
With the engine off, and the ignition key removed, check
the switches regularly to make sure they are unobstructed
by grass clippings or other material. Make sure the
electrical terminals remain clean and dry and the pivot
mechanisms for each switch operate freely.
Never spray the mower safety switches directly with highpressure water.
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49
Page 50
ELECTRICAL DIAGRAMS
MODEL 68 SR ELECTRICAL -- SAFETY SWITCH AND CIRCUIT DIAGRAM
50
MODEL 68 DL ELECTRICAL -- SAFETY SWITCH AND CIRCUIT DIAGRAM
BATTERY (Exide GT-H or equiv., 12V, U1, 235 CCA @ 0°F)1
Qty.
*Note: Your mower may be equipped with a digital hour meter. This meter will
display a signal after 5 hours, and every 25 hours thereafter, recommending that
you change the engine oil and lubricate the mower.