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