Scag Power Equipment STT-31BSG User manual

MODEL STT-31BSGMODEL STT-31BSG
MODEL STT-31BSGMODEL STT-31BSG
MODEL STT-31BSG
OPERATOR’S MANUALOPERATOR’S MANUAL OPERATOR’S MANUALOPERATOR’S MANUAL
OPERATOR’S MANUAL
THIS MANUAL CONTAINS 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. THESPECIFICMODELS THATTHIS
BOOK COVERS ARE CONTAINED ON THE
INSIDECOVER. BEFORE OPERATINGYOUR
MACHINE, PLEASE READ ALL THE INFOR-
MATION ENCLOSED.
PART NUMBER

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 Drive Train 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 OperationConsiderations........................................................................................................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 Ground Travel 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 Brake Adjustment....................................................................................................20
6.2 TravelAdjustments ...............................................................................................................20
6.3 Throttle Control and Choke Adjustments..............................................................................22
6.4 BeltAdjustment ....................................................................................................................22
6.5 BeltAlignment ......................................................................................................................22
6.6 Cutter Deck Adjustments .....................................................................................................23
Section 7 - Maintenance
7.1 Maintenance Chart ...............................................................................................................25
7.2 LubricationFittingPoints ......................................................................................................26
7.3 Hydraulic System..................................................................................................................28
7.4 EngineOil .............................................................................................................................29
7.5 Engine Fuel System ..............................................................................................................30
7.6 Engine Air Cleaner................................................................................................................30
7.7 Battery ..................................................................................................................................30
7.8 Drive Belts ............................................................................................................................32
7.9 Cutter Blades ........................................................................................................................32
7.10 Tires ......................................................................................................................................33
7.11 Cutter Deck Gearbox ...........................................................................................................34
7.12 CoolingSystem .....................................................................................................................34
7.13 Body, Deck, Hopper and Upholstery ....................................................................................35
Section 8 - Illustrated Parts List
SMST 61"Adv., 72" Adv. Cutter Decks ................................................................................... 36-37
Cutter Deck Controls................................................................................................................ 38-39
Sheet Metal Components.......................................................................................................... 40-41
Deck Drive Components .......................................................................................................... 42-43
Radiator, Coolers & Engine Brackets.................................................................................44-45
Brake & Steering Components..........................................................................................46-47
Fuel & Hydraulic System ......................................................................................................... 48-49
Electrical System ...................................................................................................................... 50-51
Hydraulic Pump Assembly - BDP-21L .................................................................................... 52-53
Wire Harness, STT-31BSG ............................................................................................................54
Replacement Decals................................................................................................................. 55-56

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 Figure 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.
All information is based upon product information
available at the time of approval for printing. Scag
Power Equipment reserves the right to make
changes at any time without notice and without
incurring 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 1-1Tractor Serial Number Plate Location
390S0137A
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
5,118,617
5,826,416
5,832,708
5,865,018

4
SAFETY INFORMATION
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. Please indicate the complete model
and serial number of your Scag product when requesting
replacement manuals.
2.2 SIGNAL WORDS
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:
It 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 irrepairable
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
properinstructions.
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.
5. DO NOT operate the machine under the influence
of alcohol or drugs.
6. If the operator(s) or mechanic(s) cannot read English
it is the owner's responsibility to explain this material
to them.
WARNING:
Section 2

8
SPECIFICATIONS
SCAG "SABRE TOOTH TIGER" ZERO-TURN RIDER
MODEL: STT-31BSG
ENGINE
General Type: Heavy duty industrial commercial
Brand: Briggs Daihatsu Vanguard Liquid Cooled 31 HP
Model: DM950G
Horsepower: 31HP@3600RPM
Type: Water cooled 4 cycle, overhead valve, 3 cylinder, gas engine
Displacement: 952cc
Cylinders: 3 inline sleeves
Governor: High-speed flyweight governor, runs faster than engine crankshaft, provides precision speed
governing and a steady low idle, 3600 rpm (±100 rpm), idle set at 1500 rpm.
Air Intake Group: Canister type air filter system.
Exhaust Group: Single exhaust canister muffler.
FuelPump Group: Electric fuel pump with mechanical choke and fuel shutdown solenoid.
OilPumpGroup: Positive displacement Geroter™ oil pump with remote oil filter, capacity 3.2 U.S. quarts
(3.0ltrs) withoilfilter.
ValveGroup: Overhead.
Electrical/ChargingSystem: 12 volt battery with alternator, solid state ignition with key start, 40 amp regulated charging
system using a microprocessor and one ignition coil for each cylinder, solenoid shift type
starter.
ENGINEDECK
FuelTank: 10 gallon (38.0 liters) seamless polyethylene tank with fuel gauge gas cap.
Drive Wheels/Tires: 24 x 12-12 four ply pneumatic tubeless, radius edge, offset rims to improve operator's view.
ParkingBrake: Lever operated interlocked parking brake prevents operation with parking brake engaged.
Frame: Compact tractor frame with structural steel tubing construction.
DRIVESYSTEM
Type: Hydro drive with two variable displacement pumps and two cast iron motors for independent control
of each drive wheel.
Hydro Pumps: Two Hydro-Gear Model BDP 21L pumps with dump valves for movement without running engine.
Drive Wheel Motors: Two 23 cubic inch cast iron high torque wheel motors.
TransmissionBelt Idler: Self adjusting, self tightening, sealed bearings.
Hydro Fluid Cooling Group: 6 qt. capacity Nylon fluid reservoir. Uses SAE 20W50 fluid and 10 micron filter.
Steering/Travel Control: Twin lever fingertip steering control with gas shock dampeners for smooth, responsive control to
each wheel.
Axles: 1-1/4" heavy duty, tapered, motor shafts.
Wire Harness: 14 gauge wire.
Safety Group: Seat actuated engine kill, neutral interlock, mower engagement (BBC) switch, parking brake.
Instrument Panel: Voltmeter, water temperaturegauge, oil pressuregauge, key switch,throttle, fuses, manual choke,BBC
switch (hourmeter located at rear of machine).
Forward Ground Speed Range: 0to 10.5 mph.
Reverse Ground Speed Range: 0 to 5.0mph.
Note: The machine will travel at 10.5 mph for transport purposes. For best cutting performance the
forward travel speed should be adjusted depending upon the cutting conditions.
Section 3

9
SPECIFICATIONS (con't)
SCAG "SABRE TOOTH TIGER" ZERO-TURN RIDER
MODEL: STT-31BSG
CUTTERDECK
Type: SMST-72A ("Advantage") & SMST-61A ("Advantage"): Floating, adjustable anti-scalping, hybrid
design combines out-front and belly-mount designs. "Advantage" - special extended front edge
allows Bahia or other tough grasses to enter the deck standing upright.
Construction: 10 gauge steel top reinforced with 7 gauge support plate, deck skirt is 7 gauge steel.
True Cutting Width: 72"deck= 71.5inches (181.6cm);61" deck= 61.0"(155.0cm).
Cutting Height Adjustment: Foot operated pedal adjustment from operator's seat, 1" to 6" in 1/2" increments.
Cutter Blades: 72" = three (3) 24" blades; 61" = three (3) 21" blades.
CutterDeck Drive: Drive shaft to 90 degee gear box.
BladeEngagement: Electric blade engagement clutch with control panel knob.
Discharge Opening: Extra wide 11.5" discharge opening with spring loaded discharge chute.
Caster Wheels: 13 x 5 x 6 caster wheels with tapered roller bearing pivots.
Spindles: Heavy duty 1-1/8" top dimension spindle shaft, cast housing, taper roller bearing, low maintenance
with top access grease fitting and grease overfill relief poppet.
Spindle Pulleys: Cast iron with easily removed taper hubs.
Anti-scalp Rollers: Two front, two rear 4-1/2" adjustable, two rear 12" fixed.
ADDITIONALSPECIFICATIONS
Seat: Thick padded seat cushions with special springs. Padded arm rests, lever adjustment forward and
back.
APPROXIMATEDIMENSIONS
72" 61"
Length: 92.0" 88.0"
Tracking Width: 56.0" 56.0"
Width: 83.5" 72.0"
Width (with discharge chute up) 73.0" 61.5"
Height: 47.0" 47.0"
Turning Radius: Zero radius turn Zero radius turn
Weight: 1550 lbs. 1550 lbs.
PRODUCTIVITY
The following chart will aid you in determining how many acres your Scag mower will cut per day.
The chart is an estimate based on 8 hours per day cutting time at 4 MPH with an allowance for overlap and turns.
Cutting Width: 36" 48" 52" 61" 72"
Acres Per Day: 9.5 12.5 13.5 16 19
Dateof issue: November, 2000
Specifications Subject to Change Without Notice.
Section 3

10
Section 4
OPERATING INSTRUCTIONS
Do not attempt to operate this mower unless you
have read this manual. Learn the location and
purpose of all controls and instruments before you
operate this mower.
4.1 CONTROLS AND INSTRUMENT
IDENTIFICATION
Before operating the mower, familiarize yourself with all
mower and engine controls. Knowing the location,
function and operation of these controls is important for
safe and efficient operation of the mower.
CAUTION:
1. Ignition Switch (Figure 4-1). The ignition switch
is used to start the engine and has three positions;
OFF, ON, and START.
2. Mower Deck Switch (Figure 4-1). Used to engage
and disengage the mower drive system. Pulling up
on the switch will engage the deck drive. Pushing
down on the switch will disengage the deck drive.
3. Engine Choke Control (Figure 4-1). Used to start
a cold engine.
4. Engine Throttle Control (Figure 4-1). Used to
control the engine speed. Pushing the lever forward
increases engine speed. Pulling the lever back
decreases engine speed. Full back position is the
IDLE position. Full forward is the cutting position.
Figure 4-1 Controls and Hour Meter Instruments
CHOKE
481348
F
LEFT STEERING
CONTROL
MOWER DECK
IGNITION SWITCH
FUEL GAUGE
DUMPVALVEDUMPVALVE
FUSES
ENGINE
CHOKE
CONTROL
ENGINETHROTTLE
CONTROL
RIGHT STEERING
CONTROL
DECK LIFT
DECK RELEASE
390S0142A-1
PARKING BRAKE
CONTROL
CUTTING HEIGHT
ADJUSTMENT
PULL OUT TO ENGAGE
ON
START
PUSH INTO DISENGAGE
OFF
481669
MOWER DECK
AMMETER
MOWER DECK SWITCH
IGNITION SWITCH
TEMPERATURE GAUGE
KAWASAKI MACHINE ONLY
AMMETER
SWITCH
WATERTEMPERATURE

11
Section 4
5. Voltmeter (Figure 4-1). Indicates the condition of
the charging system. When the engine is running, in
normal operating conditions, the needle should be in
the 12 to 14 volt range.
6. Oil Pressure (Figure 4-1). Indicates engine oil
pressure. Reference the engine operator's manual
for further information.
7. Hourmeter (Figure 4-1). Indicates the number of
hours the engine has been operted. It operates
whenever the engine is running. It can be used to
keep track of maintenance intervals and the amount
of time required to perform various tasks.
7. Fuse Holders (Figure 4-1). There are two 20-amp
fuses and one 40-amp fuse that protect the mower’s
electrical system. To replace fuses, pull fuse out of
the socket and install a new fuse.
8. Left Steering Control (Figure 4-1). Used to
control the mower's left wheel when traveling
forward or reverse.
10. Right Steering Control (Figure 4-1). Used to
control the mower's right wheel when traveling
forward or reverse.
11. Parking Brake Control (Figure 4-1). Used to
engage and disengage the parking brakes. Pull the
lever back to engage the parking brakes. Push the
lever forward to disengage the parking brakes.
12. Fuel Tank Gauge (Figure 4-1). Indicates the
amount of fuel in the fuel tank.
13. Dump Valve Control Levers (Figure 4-2).
Located on the hydraulic pumps, used to “free-
wheel” the mower. Rotating the levers clockwise
until they stop allows the unit to move under
hydraulic power. The levers must be in this position
during operation of the mower. Rotating the levers
counter-clockwise allows the mower to be moved by
hand (free-wheeling).
14. Deck Lift Foot Lever (Figure 4-1). Used to raise
and lower the cutter deck.
Figure 4-2 DumpValve Control
15. Cutting Height Adjustment (Figure 4-1). Used to
set the cutter deck at the desired cutting height.
16. Deck Release Lever (Figure 4-1). Used to lock the
cutter deck in the transport position. Push the foot
pedal forward and lift up on the release lever to
release the cutter deck for normal mowing.
17. Temperature Gauge (Figure 4-1). Indicates the
operating temperature of the engine. Used on
mowers with the Kawasaki liquid cooled engine
only.
4.2 SAFETY INTERLOCK SYSTEM
The mower is equipped with a safety interlock system
that prevents the engine from starting unless the deck
drive is disengaged, the parking brake is engaged, the
steering control levers are in the neutral position and the
operator is in the seat. The interlock system shuts off
the engine if the operator leaves the seat with the steering
control levers not in the neutral position and/or the cutter
blades engaged and the parking brake not engaged.
Never operate the mower with the interlock
system disconnected or malfunctioning. Do not
disengage or bypass any switch; injury to
yourself and others or property damage could
result.
WARNING:
390S141-1
DUMP VALVE
CONTROL

12
Section 4
4.3 INITIAL RUN-IN PROCEDURES (First
Day of Use or Approximately 10 Hours)
1. Check all belts for proper alignment and wear at 2, 4
and 8 hours.
2. Change the engine oil and oil filter after the first 5
hours of operation. (See Section 7.4.)
3. Check hydraulic oil level in reservoir. (See Section
7.3.)
4. Check for loose hardware. Tighten as needed.
5. Check interlock system for proper operation. (See
Section 4.2.)
6. Check tire pressure. Adjust pressure if necessary.
(See Section 7.10.)
4.4 STARTING THE ENGINE
DO NOT USE STARTING FLUIDS. Use of starting
fluids in the air intake system may be potentially
explosive or cause a “runaway”engine condition
that could result in engine damage and/or personal
injury.
1. Be sure the fuel shutoff valve, located behind the
operator's seat, is completely open. (See section 7.5.)
2. Sit in the operator’s seat and place the steering
control levers in the neutral position.
3. Engage the parking brake.
4. Place the PTO switch in the disengaged position.
5. If the engine is cold, choke the engine as needed.
6. Move the engine throttle control to about half
engine speed.
7. Turn the ignition key to the START position and
release the key as soon as the engine starts. Do not
hold the key in the START position for more than 15
seconds at a time. Allow at least 60 seconds
between each cranking attempt to prevent
overheating of the starter motor. Prolonged cranking
can damage the starter motor and shorten battery
life.
8. Allow engine to warm before operating the mower.
4.5 GROUNDTRAVEL AND STEERING
-IMPORTANT-
If you are not familiar with the operation of a
machine with lever steering and/or hydrostatic
transmissions, the steering and ground speed
operations should be learned and practiced in
an open area, away from buildings, fences, or
obstructions. Practice until you are comfortable
with the handling of the machine before
attempting to mow. Learn the operation on flat
ground before operating on slopes.
-IMPORTANT-
Start practicing with a slow engine speed and
slow forward travel.
Learn to feather the steering controls to obtain a
smooth operating action.
Practice operating the mower until you are
comfortable with the controls before proceeding
to mow.
Forward Travel
To travel forward with the mower, disengage the parking
brake and slowly push the steering control levers
forward an equal distance. The further the steering
control levers are pushed forward the greater the forward
speed will be. To increase the speed, push the steering
control levers further forward and to decrease the speed,
pull the steering control levers back.
To stop the forward travel, pull the steering control
levers back to the neutral position.
CAUTION: