Scag Power Equipment STHM User manual

MODEL STHM
THIS MANUAL CONTAINS THE OPERATING
INSTRUCTIONS AND SAFETY INFORMATION
FOR YOUR SCAG MOWER. READING THIS
MANUAL CAN PROVIDE YOU WITH ASSIS-
TANCE IN MAINTENANCE AND ADJUST-
MENT PROCEDURES TO KEEP YOUR MOWER
PERFORMING TO MAXIMUM EFFICIENCY.
THE SPECIFIC MODELS THAT THIS BOOK
COVERS ARE CONTAINED ON THE INSIDE
COVER. BEFORE OPERATING YOUR MA-
CHINE, PLEASE READ ALL THE INFORMA-
TION ENCLOSED.
PART NUMBER 03033
OPERATOR’S MANUAL

FAILURE TO FOLLOW SAFE OPERATING PRACTICES
MAY RESULT IN SERIOUS INJURY.
* Keep all shields in place, especially the grass discharge chute.
* Before performing any maintenance or service, stop the machine and
remove the spark plug wire and ignition key.
* If a mechanism becomes clogged, stop the engine before cleaning.
* Keep hands, feet and clothing away from power-driven parts.
* Read this manual completely as well as other manuals that came
with your mower.
* Keep others off the tractor only one person at a time)
REMEMBER - YOUR MOWER IS ONLY AS SAFE AS THE OPERATOR!
Hazard control and accident prevention are dependent upon the awareness,
concern, prudence, and proper training of the personnel involved in the
operation, transport, maintenance, and storage of the equipment.
Always use the entire serial number listed on the serial number
tag when referring to this product.
WARNING:
This manual covers the operating instructions
and illustrated parts list for:
STHM-20CV with a s rial numb r of 27370001-27379999
STHM-22CV with a s rial numb r of 27470001-27479999

1
SIGNALWORDS
This symbol means Attention! Become Alert!
Your Safety is Involved!" The symbol is used
with the following signal words to attract your
attention to safety messages found on the decals and
throughout this manual. The message that follows
the symbol contains important information about
safety. To avoid injury and possible death, carefully
read the message! Be sure to fully understand the
causes of possible injury or death.
Signal Word:
It is a distinctive word on safety decals and through-
out this manual that alerts the viewer to the exist-
ence and relative degree of the ha ard.
The signal word DANGER denotes that an ex-
tremely ha ardous situation exists on or near the
machine that could result in high probability of
death or irreparable injury if proper precautions are
not taken.
The signal word WARNING denotes that a ha ard
exists on or near the machine that can result in
injury or death if proper precautions are not taken.
The signal word CAUTION is a reminder of
safety practices on or near the machine that could
result in personal injury if proper precautions are not
taken.
INTRODUCTION
Your mower was built to the highest standards in the
industry. However, the prolonged life and maximum
efficiency of your mower depends on you following
the operating, maintenance and adjustment instruc-
tions in this manual.
We encourage you to contact your dealer for repairs.
All Scag dealers are informed of the latest methods
to service this equipment and provide prompt and
efficient service in the field or at their service shop.
They carry a full line of Scag service parts.
A replacement Operator's Manual is available from
your Scag Servicing Dealer or by contacting Scag
Power Equipment, Service Department at P.O. Box
152, Mayville, WI 53050. Please indicate the com-
plete model and serial number of your Scag product.
USE O OTHER THAN ORIGINAL SCAG
REPLACEMENT PARTS WILL VOID THE
WARRANTY.
The Right and Left, Front and Rear of the
machine are referenced from the operators perspec-
tive when in the normal operating position and
facing the forward travel direction.
GENERAL SAFETY INSTRUCTIONS
READ THIS OPERATOR'S MANUAL and all
instructions furnished with attachments.
Perform only those maintenance procedures de-
scribed in this manual. If major repairs are ever
needed or assistance is desired, contact an Author-
i ed Scag Dealer. To ensure optimum performance
and safety, always purchase genuine SCAG replace-
ment parts and accessories.
Your safety and the safety of others depends signifi-
cantly upon your knowledge and understanding of
all correct operating practices and procedures of this
machine.
WARNING:
CAUTION:

2
BEFORE OPERATING
1. Know the operating controls and how to stop
quickly.
2. Do not allow children to operate the machine.
Do not allow adults to operate the machine
without proper instruction.
3. Remove all debris or other objects that might be
picked up and thrown by the cutter blades. Keep
all bystanders away from the mowing area.
4. Keep all shields, safety devices, and decals in
place. If a shield, safety device or decal is defec-
tive or damaged, repair or replace it before
operating. Also, check all nuts, bolts and screws
for proper tightness, to assure the machine is in
safe operating condition.
5. Do not operate the machine while wearing
sandals, tennis shoes, sneakers or shorts. Also,
do not wear loose fitting clothing which could get
caught in moving parts. Always wear long pants
and substantial shoes. Wearing safety glasses and
safety shoes is advisable and required by some
local ordinances and insurance regulations.
6. Fill the fuel tank with clean, fresh gasoline, with a
minimum octane rating of 87. Avoid spilling
gasoline. Gasoline is highly flammable, handle it
carefully.
A. Use an approved gasoline container.
B. Do not fill the tank while the engine is hot or
running.
C. Do not smoke while handling gasoline.
D. Fill the fuel tank outdoors and up to approxi-
mately 1" (25 mm) below the bottom of the
filler neck.
E. Wipe up any spilled gasoline.
7. Before attempting to start the engine, move the
blade engagement switch to the OFF position and
apply the parking brake.
WHILE OPERATING
1. Start the engine when the cutter blades are
disengaged, the parking brake is on and the right
foot pedal is in the neutral position.
2. Do not run the engine in a confined area without
adequate ventilation. Exhaust fumes are ha ard-
ous and could possibly be deadly.
3. Using the machine demands attention. To
prevent loss of control:
A. Mow only in daylight or when there is good
artificial light.
B. Watch for holes or other hidden ha ards.
C. Do not drive close to a drop-off, ditch, creek
bank, or other ha ard.
D. Reduce speed when making sharp turns and
when turning on hillsides.
E. Do not operate where conditions are slippery.
4. The discharge chute must always be installed and
in the down position on the side discharge cutter
deck except when the Scag optional grass
catcher or mulching plate are properly installed.
If the discharge area should plug, shut the engine
off and wait for all movement to stop before
removing the obstruction.
5. Disengage the blades and wait for them to stop
before crossing gravel drives, walks or roads.
6. Shut the engine off and wait until the blades
come to a complete stop before removing the
grass catcher container.
7. Never raise the cutter deck while the blades are
rotating.
8. Always park the mower and/or start the engine
on a level surface. Apply the parking brake to
prevent the mower from moving when you are
not in the operators position.

3
13. Do not pass or stand on the grass discharge side
of any mower with the engine running. Stop the
cutter blades when another person approaches.
9. If the cutting blades should strike a solid object
or the equipment should start to vibrate abnor-
mally, stop the engine, disconnect the spark plug
wire, and check immediately for the cause.
Vibration is generally a warning of trouble.
Check the machine for damaged or defective
parts. Repair any damage before starting the
engine or operating the cutter deck. Be sure the
blades are in good condition and the blade bolts
are tight.
10. Reduce speed and exercise extreme caution on
slopes and in sharp turns to prevent tipping or
loss of control. Be especially cautious when
changing directions on slopes.
DO NOT operate on steep slopes. To check a
slope, attempt to back up it (with the cutter deck
down). If the machine can back up the slope
without the wheels slipping, reduce speed and
use extreme caution. ALWAYS FOLLOW OSHA
APPROVED OPERATION.
11. Do not touch the engine or muffler while the
engine is running or soon after it is stopped.
These areas could be hot enough to cause a burn.
12. Before leaving the operators position or leaving
the mower unattended, move the right foot pedal
into the neutral position, apply the parking brake,
and move the blade engagement switch to OFF.
Shut the engine OFF and remove the key.
MAINTENANCE AND STORAGE
1. Disconnect the spark plug wire from the spark
plug to prevent accidental starting of the engine
when servicing, adjusting or storing the machine.
2. If the mower must be tipped to perform mainte-
nance or adjustment, remove the battery, drain
the gasoline from the fuel tank and the oil from
the crankcase.
3. To reduce potential fire ha ard, keep the engine
free of excessive grease, grass, leaves and accu-
mulations of dirt.
4. Be sure the machine is in safe operating condition
by keeping nuts, bolts, and screws tight. Check
the blade mounting bolts and nuts frequently to
be sure they are tightened.
5. If the engine must be running to perform a
maintenance adjustment, keep hands, feet, cloth-
ing and other parts of the body away from the
cutter deck blades and other moving parts.
6. Do not overspeed the engine by changing gover-
nor settings. To be sure of safety and accuracy,
have an authori ed dealer check maximum engine
speed with a tachometer.
7. The engine must be shut off before checking the
oil or adding oil to the crankcase.
8. Allow the engine to cool before storing the
mower in any enclosure such as a garage or
storage shed. Make sure the fuel tank is empty if
the machine is to be stored in excess of 30 days.
Do not store the mower near any open flame or
where gasoline fumes may be ignited by a spark.
WARNING:

4
9. Always store gasoline in a safety-approved, red
container.
10. Be careful when servicing the battery as it con-
tains acid, which is corrosive and could cause
burns to skin and clothing.
11. Batteries release explosive gases when being
charged or discharged. Keep batteries away from
any source of sparks and/or flame.
12. Make sure all hydraulic connections are tight and
all hydraulic hoses and lines are in good condi-
tion before starting the machine.
13. Hydraulic fluid is under high pressure. If you
need service on your hydraulic system, please see
your authori ed Scag dealer.
INITIAL RUN-IN PROCEDURES
(FIRST DAY OF USE OR APPROXI-
MATELY 10 HOURS)
1. Check the belts for proper tension at 2, 4 and 8
hours. Adjust as needed. (See Belt Tension,
page 7).
2. Check the neutral adjustment. (See Adjust-
ments, page 6)
3. Check the tires for proper pressure.
Caster Wheels 25 psi.
Drive Wheels 15 psi.
Rear Steering Wheel 15 psi
4. Check for loose hardware. Tighten as needed.
5. Check the safety switches for proper adjustment:
* The engine should crank and start if the
machine is in neutral, the PTO engage-
ment switch is OFF and the parking brake
is ON.
6. Apply lubricant to all the grease fittings. Lubri-
cant was applied at the factory. This is just a
precautionary check to make sure that all the
fittings have been lubricated.
MOWER OPERATION
-NOTE-
Use gasoline with an octane rating no less than
87.
* The right hand foot pedal must be in the
NEUTRAL position.
* The blade clutch switch must be in the OFF
position.
* The parking brake must be ON.
3. Start the engine:
* Choke as required. If the engine is cold, pull
the choke knob out. When the engine starts,
slowly push the choke in. If the engine stalls,
repeat the above operation. When the engine
is warm, choking may not be necessary.
4. Depress the left hand operator presence pedal.
5. Engage the cutter blades by lifting and pushing
the blade cluch switch into the ON position. Pull
the switch to the OFF position to disengage the
cutter blades.
-NOTE-
When the PTO is engaged or (possibly) disen-
gaged, a sq ealing so nd from the nderside of
the machine is normal. It is ca sed by the
electric cl tch plates meshing as the c tter
blades come p to speed. For best eq ipment
life, engage the cl tch with the engine at 1/2
throttle, not nder f ll load.
1. Read and understand the safety instructions
before attempting to operate this machine.
2. Before starting the engine:
* Check the oil level in the engine and the
hydraulic reservoir.
* Fill the fuel tank with clean, fresh, lead-free
gasoline.
* Open the fuel valve on the bottom of the
fuel tank.

5
If you are not familiar with the operation of the
hydrostatic drive, practice turning and maneuver-
ing before engaging the cutter blades.
5. Release the parking brake. Depress the right
foot pedal at the toe end to drive forward (See
Figure 1) or depress the pedal at the heel end to
drive in reverse. (See Figure 2)
-NOTE-
The left hand operator presence pedal m st be
depressed for operation.
6. When driving over curbs, disengage the cutter
blades, raise the cutter deck to clear the curb.
Drive forward over the curb. After the curb is
clear lower the cutter deck back to normal
operating position. Be sure to leave slack in the
cable after lowering the cutter deck.
PARKING BRAKE
Minor brake adjustments can be made by loosen-
ing the top nut on both brake cables (see figure
4). Back the nuts off approximately 1/4". While
pulling one cable downward, tighten the bottom
nut on the cable until it touches the bottom of the
brake cable mount. Tighten both the top and
bottom nuts to lock the cable in place. Repeat
the above steps for the second brake cable. Make
sure that both cables are adjusted evenly so that
the brakes do not cause the mower to pull to the
left or right.
-NOTE-
This is a minor brake adj stment. If the
brakes do not f nction properly after this
adj stment, see yo r Scag Service Dealer
before operating yo r mower.
Forward Operation - Depress Toe End of Pedal
Figure 1
Figure 2
Backward (Reverse) Operation - Depress Heel
End of Pedal
7. To "freewheel" or move the machine around
without the engine running, rotate the dump valve
lever located on the left rear of the engine deck to
the freewheel position (See Figure 3). The lever
must be returned to the drive position to operate
the machine.
Figure 3. Dump Valve Location
ADJUSTMENTS
WARNING:
SGB003
DUMP VALVE
FREE
WHEEL DRIVE
SGB006
sgb002
-NOTE-
To prevent damage to the hydra lic system, do not
exceed 1MPH when moving the machine in the
freewheel postion.

6
Figure 4. Parking Brake Adjustment
NEUTRAL ADJUSTMENT
1. Set the engine deck up on jack stands so the
wheels are free to rotate.
2. Block the caster wheels to prevent an accident
should the machine fall off the jack stands.
3. Start the engine and determine if the drive wheels
rotate.
If the drive wheels consistently rotate when foot
pedal control is in neutral, go to step 4.
If the drive wheels inconsistently rotate, i.e. drive
wheels sometimes rotate and sometimes do not
when foot pedal is not depressed, then check
neutral adjustment bolt for " ero free play" in
neutral control spring.
-NOTE-
DO NOT OVERTIGHTEN. If yo t rn the
adj stment bolt too m ch yo will compress the
spring, making too m ch end play. Go to step 4.
4. If the drive wheels rotate in the forward travel
direction, turn the adjustment bolt clockwise until
the tire rotation stops. If the drive wheels rotate
in the backward travel direction, turn the adjust-
ment bolt counter-clockwise until the tire rota-
tion stops (See Figure 5).
Figure 5. Neutral Adjustment
Figure 6. Foot Control Pedal Adjustment
5. Check the adjustment of the right foot control
pedal for full forward speed. The pedal should
rest on the foot plate when the pump is stroked in
the full forward position. To make an adjust-
ment, disconnect the ball joint from the pedal arm
and loosen the jam nut (See Figure 6). Place the
foot control pedal forward against the foot rest
and adjust the ball joint on the rod until the stud
aligns with the hole in the arm. Bolt the ball joint
to the arm and tighten the jam nut.
SGB028
Adjust
Nuts
SGB029
Neutral Control
Spring
9/16" Socket
SGB030
Jam Nut
Ball Joint

7
Use of Tension Gauge
sgb007
BELTTENSION
Stop engine and remove the key from the ignition
before making any adjustments. Wait for all moving
parts to come to a complete stop before beginning
work.
-NOTE-
The Hydro Drive Belt is spring-loaded and
does not req ire adj stment.
To adjust cutter deck drive and blade belts:
1. Remove belt cover.
2. To adjust cutter deck drive belt: Adjust the nut so
that the belt moves 1/2" with 10 pounds of pres-
sure. (See Figure 7).
6. Start the engine. The wheels should rotate only
when the foot control pedal is depressed.
CAUTION:
Figure 7. Cutter Deck Drive Belt Tension
3. To adjust blade drive belt: Using a belt tension
gauge, check the belt tension so that the belt
moves 1/2" with 10 pounds of pressure. (See
Figure 8).
4. Replace the belt covers.
Adjust the tension by tightening or loosening the nut
on the J-bolt.
Figure 8. Blade Drive Belt Tension Check
Figure 9. Blade Belt Tension Adjustment
BELT ALIGNMENT
Belt alignment is important for proper performance
of your Scag mower. If you experience frequent
belt wear or breakage, see your authori ed Scag
Service Dealer for belt adjustment.
SGB031
Deck
"J" Bolt
Nut
Washer
Belt

8
CUTTER DECK ADJUSTMENTS
Due to the many conditions that exist, it is difficult
to suggest a setting that will work for every lawn.
There are, however, two adjustments that should be
made on the cutter deck: pitch and height.
PITCH is the angle of the blades (comparing front
to rear).
HEIGHT is the nominal distance that the blade is
off the ground. This measurement is made with the
blades pointed side to side and distance is measured
between cutting tip and ground.
Adjusting the blade height can be done by moving
any number of the five smaller spacers on the blade
mounting bolts to the top of the spindle shaft or to
the bottom of the spindle shaft. All blades should be
positioned equally (See Figure10).
The unit is shipped with one spacer on top of spindle
and four underneath (See Figure 10).
This adjustment does not affect blade pitch.
-NOTE-
For best res lts, keep the c tter deck
high in relation to the engine deck and
the blades low in the c tter deck; ie. 4 or
5 spacers below the spindle shaft.
Additional range to the cutting height can be
achieved by repositioning the cutter deck in relation-
ship to the engine deck. This adjustment also affects
the pitch of the deck.
There are three positions for mounting the cutter
deck (See Figure 11). For cutting in the lowest
position, mount the cutter deck in the top hole (A).
For cutting in the highest position, mount the deck in
the lowest hole (C). Setting the cutter deck height
will be determined by the type of cutting conditions.
Caster spacers also can be repositioned to change
the cutting heights and to change the pitch of the
deck (See Figure 12).
To adjust the caster spacers, raise the deck and
remove the pin and caster wheel. Reposition the
caster spacers as needed, then replace the caster, top
spacers and pin. Make the same adjustments on the
other caster wheel.
To adjust the blade height, move any number of the
five 1/4" thick spacers on the blade mounting bolts
to the top of the spindle shaft or below the spindle
shaft.
Hex Nut-Torque
to 75 Lb-Ft Cutter Blade
Spacer 1/4"
Spindle
Shaft Cutter
Deck
Spindle
Assembly Hex Head
Bolt / Nut
Cutter Blade
Spacers1/4"
Washer
Hex Head Bolt Cutter Blade
Figure 10. Cutter Blade Adjustment
Figure 11. Cutter Deck Height Adjustment
SGB032
A
B
C