Scag Power Equipment STT-31BSG User manual

MODEL STT-31BSG
OPERATOR’S MANUAL
THIS MANUALCONTAINS THE OPERATING
INSTRUCTIONS AND SAFETY INFORMA-
TION FOR YOUR SCAG MOWER. READING
THIS MANUAL CAN PROVIDE YOU WITH
ASSISTANCE IN MAINTENANCE AND AD-
JUSTMENT PROCEDURES TO KEEP YOUR
MOWER PERFORMING TO MAXIMUM EFFI-
CIENCY. THE SPECIFIC MODELS THATTHIS
BOOK COVERS ARE CONTAINED ON THE
INSIDECOVER. BEFORE OPERATINGYOUR
MACHINE, PLEASE READ ALL THE INFOR-
MATION ENCLOSED.
PART NUMBER 03121

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 wires and ignition key.
* Ifa mechanism becomes clogged,stop the engine beforecleaning.
* Keep hands, feet and clothing away from power-driven parts.
* Read this manual completely as well as other manuals that came
withyourmower.
* Keep others off the tractor (only one person at a time)
REMEMBER -YOUR MOWER IS ONLY AS SAFE ASTHE 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.
This manual covers the operating instructions
and illustrated parts list for:
STT-31BSG with a serial number of 8580001 to 8589999
SMST-61A with a serial number of 8600001 to 8609999
SMST-72A with a serial number of 8610001 to 8619999
Always use the entire serial number listed on the serial number
tag when referring to this product.
WARNING:

I
TABLE OF CONTENTS
SUBJECT PAGE
Section 1 - General Information
1.1 Introduction .............................................................................................................................1
1.2 Directional Reference.............................................................................................................1
1.3 Servicing the Engine and DriveTrain Components ................................................................1
Section 2 - Safety Information
Symbols ............................................................................................................................... 2-3
2.1 Introduction .............................................................................................................................4
2.2 SignalWords ...........................................................................................................................4
2.3 Before Operation Considerations ...........................................................................................4
2.4 Operation Considerations........................................................................................................5
2.5 Maintenance Considerations ...................................................................................................6
2.6 Safety and Instructional Decals ..............................................................................................7
Section 3 - Specifications .......................................................................................................8-9
Section 4 - Operating Instructions
4.1 Controls and Instrument Identification ..................................................................................10
4.2 Safety Interlock System........................................................................................................ 11
4.3 Initial Run-In Procedures......................................................................................................12
4.4 Starting the Engine................................................................................................................12
4.5 GroundTravel and Steering ..................................................................................................12
4.6 Engaging the Deck Drive .....................................................................................................13
4.7 HillsideOperation .................................................................................................................14
4-8 Parking the Mower ...............................................................................................................14
4.9 After Operation ....................................................................................................................14
4.10 Removing Clogged Material .................................................................................................15
4.11 Moving Mower with Engine Stopped ...................................................................................15
4.12 Recommendations for Mowing.............................................................................................15
4.13 Adjusting CuttingHeight .......................................................................................................16
Section 5 -Troubleshooting Cutting Conditions............................................................. . 17-19

II
TABLE OF CONTENTS (CONT'D)
SUBJECT PAGE
Section 6 - Adjustments
6.1 Parking BrakeAdjustment....................................................................................................20
6.2 TravelAdjustments ...............................................................................................................20
6.3 Throttle Control and ChokeAdjustments..............................................................................22
6.4 BeltAdjustment ....................................................................................................................22
6.5 BeltAlignment ......................................................................................................................22
6.6 Cutter Deck Adjustments .....................................................................................................23
Section 7 - Maintenance
7.1 Maintenance Chart ...............................................................................................................26
7.2 LubricationFitting Points ......................................................................................................27
7.3 Hydraulic System..................................................................................................................29
7.4 EngineOil .............................................................................................................................30
7.5 Engine Fuel System ..............................................................................................................31
7.6 EngineAir Cleaner................................................................................................................31
7.7 Battery ..................................................................................................................................31
7.8 Drive Belts ............................................................................................................................33
7.9 Cutter Blades ........................................................................................................................33
7.10 Tires ......................................................................................................................................34
7.11 Cutter Deck Gearbox ...........................................................................................................35
7.12 CoolingSystem .....................................................................................................................35
7.13 Body, Deck, Hopper and Upholstery ....................................................................................36
Section 8 - Illustrated Parts List
SMST 61"Adv., 72"Adv. Cutter Decks ................................................................................... 38-39
Cutter Deck Controls................................................................................................................ 40-41
Sheet Metal Components.......................................................................................................... 42-43
Deck Drive Components .......................................................................................................... 44-45
Radiator, Coolers & Engine Brackets.................................................................................46-47
Brake & Steering Components..........................................................................................48-49
Fuel & Hydraulic System ......................................................................................................... 50-51
Electrical System ...................................................................................................................... 52-53
Hydraulic Pump Assembly - BDP-21L .................................................................................... 54-55
Wire Harness, STT-31BSG ............................................................................................................56
Replacement Decals................................................................................................................. 57-58

1
GENERAL INFORMATION
1.1 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 instructions in
this manual.
If additional information or service is needed, contact
your Scag Power Equipment Dealer.
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.
USE OF OTHER THAN ORIGINAL SCAG
REPLACEMENT PARTS WILL VOID THE
WARRANTY.
When ordering parts, always give the model and serial
number of your tractor. The serial number plate is
located where shown in Figures 1-1.
For pictorial clarity, some illustrations and figures in this
manual may show shields, guards or plates open or
removed. Under no circumstances should your mower be
operated without these devices in place.
Allinformationis based uponproductinformation
available at the time of approval forprinting. Scag
PowerEquipment reserves the rightto make changes
atany time withoutnotice andwithoutincurring any
obligation.
1.2 DIRECTION REFERENCE
The “Right” and “Left”, “Front” and “Rear” of the
machine are referenced from the operator’s right and left
when seated in the normal operating position and facing
the forward travel direction.
1.3 SERVICING THE ENGINE AND DRIVE
TRAIN COMPONENTS
The detail servicing and repair of the engine, hydraulic
pumps and gearboxes are not covered in this manual;
only routine maintenance and general service instructions
are provided. For service of these components during the
limited warranty period, it is important to contact your
Scag dealer or find a local authorized servicing agent of
the component manufacturer. Any unauthorized work
done on these components during the warranty period
may void your warranty.
Section 1
Figure 1-1 Tractor Serial Number Plate Location
390S0137
SERIAL NUMBER 
PLATE LOCATION
R
MODEL
SERIAL
Division of Metalcraft of Mayville, Inc.

Mayville, Wisconsin 53050

Patents Issued and Pending
MANUFACTURED UNDER ONE OR MORE

OF THE FOLLOWING PATENTS:
PATENTS PENDING
4,487,006

4,885,903

4,920,733

4,967,543
4,991,382

4,998,948

4,118,617

2
CE Mark
TransmissionChoke
On/Start Spring Tension on Idler
Oil
Off/Stop
SYMBOL DESCRIPTION
SYMBOL DESCRIPTION
ISO Symbols
SpinningBlade
48071S
Parking Brake
WARNING
FALLING HAZARD 
USE ONLY SCAG APPROVED 
RIDING ATTACHMENTS
SEE OPERATOR'S MANUAL
481109
FallingHazard

3
Slow
Fast
Cutting Element - Engage
Cutting Element - Basic symbol
Cutting Element - Disengage
Continuously Variable - Linear
Read Operator's Manual
Keep Bystanders Away
Pinch Point
481039S
SYMBOL DESCRIPTION SYMBOL DESCRIPTION
Hourmeter/Elapsed Operating Hours
Thown Object Hazard

4
SAFETY INFORMATION
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 on the machine 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:
The signal word is a distinctive word found on the safety
decals on the machine and throughout this manual that
alerts the viewer to the existence and relative degree of
the hazard.
The signal word “WARNING” denotes that a hazard
exists on or near the machine that can result in injury or
death if proper precautions are not taken.
The signal word “DANGER” denotes that an extremely
hazardous situation exists on or near the machine that
could result in high probability of death or irreparable
injury if proper precautions are not taken.
CAUTION:
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.
Your safety and the safety of others depends significantly
upon your knowledge and understanding of all correct
operating practices and procedures of this machine.
2.3 BEFORE OPERATION
CONSIDERATIONS
1. NEVER allow children to operate this riding mower.
Do not allow adults to operate this machine without
proper instructions.
2. DO NOT mow when children and/or others are
present.
3. Clear the area to be mowed of objects that could be
picked up and thrown by the cutter blades.
4. DO NOT carry passengers.
WARNING:
Section 2
2.1 INTRODUCTION
Your mower is only as safe as the operator.
Carelessness or operator error may result in serious
bodily injury or death. 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. Make sure every operator is properly trained
and thoroughly familiar with all of the controls before
operating the mower.
READ THIS OPERATOR’S MANUAL BEFORE
ATTEMPTING TO START YOUR MOWER.
A replacement manual is available from your authorized
Scag Service Dealer or by contacting Scag Power
Equipment, Service Department at P.O. Box 152,
Mayville, WI 53050 or contact us via the Internet at
www.scag.com. Use the contact form to make your
request. Please indicate the complete model and serial
number of your Scag product when requesting
replacement manuals.
2.2SIGNALWORDS

5
10. DO NOT add fuel to a running or hot engine. Allow
the engine to cool for several minutes before adding
fuel.
11. Keep flammable objects (cigarettes, matches, etc.),
open flames and sparks away from the fuel tank and
fuel container.
12. Equipment must comply with the latest requirements
per SAE J137 and/or ANSI/ASAE S279 when
driven on public roads.
If the mower is driven on public roads, it must
comply with state and local ordinances as well as
SAE J137 and/or ANSI / ASAE S279
requirements. Contact your local authorities for
regulations and equipment requirements.
13. DO NOT operate without the side discharge chute
installed and in the down position.
14. Check the blade mounting bolts at frequent intervals
for proper tightness.
15. Make sure all hydraulic fluid connections are tight
and all hydraulic hoses and lines are in good condition
before starting the machine.
2.4 OPERATION CONSIDERATIONS
1. Know the function of all controls and how to stop
quickly.
2. 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.
6. Operator hearing protection is recommended,
particularly for continuous operation of the mower.
Wear suitable hearing protection. Prolonged
exposure to loud noise can cause hearing
impairment or hearing loss.
7. Keep the machine and attachments in good
operating condition. Keep all shields and safety
devices in place. If a shield, safety device or decal
is defective or damaged, repair or replace it before
operating the machine.
Thismachine is equipped with an interlock system
intended to protect the operator and others from
injury. This is accomplished by preventing the
2.3 BEFORE OPERATION
CONSIDERATIONS (CONT'D)
5. DO NOT wear loose fitting clothing that could get
tangled in moving parts. Do not operate the machine
wearing shorts; always wear adequate protective
clothing including long pants. Wearing safety
glasses, safety shoes and a helmet is advisable and is
required by some local ordinances and insurance
regulations.
Section 2
WARNING:
engine from starting unless the deck drive is
disengaged, the parking brake is on, the steering
control levers are in the neutral position and the
operator is in the seat. The system shuts off the
engine if the operator leaves the seat with the deck
driveengagedand/or the steering control levers are
not in the neutral postion and the parking brake is
not engaged. Never operate equipment with the
interlock system disconnected or malfunctioning.
8. Be sure the interlock switches are functioning
correctly.
9. Fuel is flammable; handle it with care. Fill the fuel
tank outdoors. Never fill it indoors. Use a funnel or
spout to prevent spillage. Clean up any spillage
before starting the engine.
-NOTE-
WARNING:

6
Section 2
2.4 OPERATION CONSIDERATIONS
(CONT'D)
3. To prevent tipping or loss of control, start and stop
smoothly, avoid unnecessary turns and travel at
reduced speed.
4. When using any attachment, never direct the
discharge of material toward bystanders or allow
anyone near the machine while in operation.
5. Before attempting to start the engine, with the
operator in the seat, disengage power to the cutter
deck, place the steering control levers in the neutral
position and engage the parking brake.
6. If the mower discharge ever plugs, shut off the
engine, remove the ignition key, and wait for all
movement to stop before removing the obstruction.
Do not use your hand to dislodge the clogged
discharge chute. Use a stick or other device to
remove clogged material.
7. Be alert for holes, rocks, roots and other hidden
hazards in the terrain. Keep away from any dropoff.
Beware of overhead obstructions (low limbs, etc.),
underground obstacles (sprinklers, pipes, tree roots,
etc.). Cautiously enter a new area. Be alert for
hidden hazards.
8. Disengage power to the cutter deck before backing
up. Do not mow in reverse unless absolutely
necessary and then only after observation of the
entire area behind the mower.
9. DO NOT turn sharply. Use care when backing up.
10. Disengage power to the cutter deck before crossing
roads, walks or gravel drives.
11. Mowonlyin daylight or good artificial light.
12. Take all possible precautions when leaving the
machine unattended, such as disengaging the mower,
lowering the attachments, setting the parking brake,
stopping the engine, and removing the key.
13. Disengage power to the attachments when
transporting or when not in use.
14. The machine and attachments should be stopped and
inspected for damage after striking a foreign object,
and damage should be repaired before restarting and
operating the machine.
15. DO NOT touch the engine or the muffler while the
engine is running or immediately after stopping.
These areas may be hot enough to cause a burn.
16. DO NOT run the engine inside a building or a
confined area without proper ventilation. Exhaust
fumes are hazardous and could cause death.
2.5 MAINTENANCE CONSIDERATIONS
1. Never make adjustments to the machine with the
engine running unless specifically instructed to do so.
If the engine is running, keep hands, feet, and
clothing away from moving parts.
2. Remove the key from the ignition switch to prevent
accidental starting of the engine when servicing or
adjusting the machine.
3. Keep all nuts, bolts and screws tight, to ensure the
machine is in safe working condition.
4. Do not change the engine governor settings or
overspeed the engine. See the engine operator's
manual for information on engine settings.
5. To reduce fire hazard, keep the engine free of grass,
leaves, excessive grease, oil and dirt.
6. Hydraulic fluid is under high pressure. Keep
body and hands away from pinholes or nozzles that
eject hydraulic fluid under high pressure. If you
need service on your hydraulic system, please see
your authorized Scag dealer. Hydraulic fluid under
high pressure may have sufficient force to penetrate
skin and cause serious injury. If hydraulic fluid is
injected into the skin, it must be surgically removed
within a few hours by a doctor or gangrene may
result.