Hobart 140GT17P, 140GT17K, 140GT17P5 Operation And Maintenance Manual With Illustrated Parts List

OM-2029

010187
Revised 093089
Revised 031690
Revised 072790
Revised 040893

OPERATION AND MAINTENANCE MANUAL

with

ILLUSTRATED PARTS LIST

for

ENGINE-DRIVEN GENERATOR SETS

SERIES 6906

Models 140GT17P, 140GT17K, and 140GT17P5

140-KVA, 400-HZ, 115/200-V AC, 3-PHASE

SPEC. No. DESCRIPTION

6906-1 Basic Series 6906 generator set, trailer-mounted
6906-2 Basic Series 6906 generator set, truck-mounted
6906-3 Basic Series 6906 generator set, mounted on

5th-wheel trailer, with T-R provisions, fuel tank,

battery, and trays for battery and cables.

6906-4 Basic Series 6906 generator set, truck-mounted,

and equipped with magnetic amplifier type voltage

regulator, Part No. 281407

6906-5 Basic Series 6906 generator set, mounted on 5th-wheel

trailer

6906-6 Basic Series 6906 generator set, mounted on 5th-wheel

trailer, with fuel tank, cable tray, battery/cable tray,
rear fenders, and rear bumper

Hobart Brothers Company

Airport Systems Group

Ground Power Equipment

Troy, Ohio 45373

U.S.A.

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SAFETY INSTRUCTIONS AND WARNINGS FOR ELECTRICAL POWER EQUIPMENT

WARNING

ELECTRIC SHOCK can KILL. Do not touch live electrical parts.

ELECTRIC ARC FLASH can injure eyes, burn skin, cause equipment damage, and ignite combustible

material. DO NOT use power cables to break load and prevent tools from causing short circuits.

IMPROPER PHASE CONNECTION, PARALLELING, OR USE can damage this and attached

equipment.

Important:- Protect all operating personnel. Read, understand, and follow all instructions in

the Operating/Instruction Manual before installing, operating, or servicing the equipment. Keep
the manual available for future use by all operators.

A. GENERAL

Equipment that supplies electrical power can cause serious injury or death, or damage to other equipment
or property. The operator must strictly observe all safety rules and take precautionary actions. Safe practices
have been developed from past experience in the use of power source equipment. While certain practices be­low apply only to electrically-powered equipment, other practices apply to engine-driven equipment, and some
practices to both.

B. SHOCK PREVENTION

Bare conductors, or terminals in the output circuit, or ungrounded, electrically-live equipment can fatally
shock a person. Have a certified electrician verify that the equipment is adequately grounded and learn what
terminals and parts are electrically HOT. Avoid hot spots on machine. Use proper safety clothing, procedures,
and test equipment.

The electrical resistance of the body is decreased when wet, permitting dangerous currents to flow
through it. When inspecting or servicing equipment, do not work in damp areas. Stand on a dry rubber mat
or dry wood, use insulating gloves when dampness or sweat cannot be avoided. Keep clothing dry, and
never work alone

1. Installation and Grounding of Electrically Powered Equipment

Equipment driven by electric motors (rather than by diesel or gasoline engines) must be installed and
maintained in accordance with the National Electrical Code, ANSI/NFPA 70, or other applicable codes. A
power disconnect switch or circuit breaker must be located at the equipment. Check the nameplate for volt­age, frequency, and phase requirements. If only 3-phase power is available, connect any single-phase rated
equipment to only two wires of the 3-phase line. DO NOT CONNECT the equipment grounding conductor
(lead) to the third live wire of the 3-phase line, as this makes the equipment frame electrically HOT, which can
cause a fatal shock.

Always connect the grounding lead, if supplied in a power line cable, to the grounded switch box or build­ing ground. If not provided, use a separate grounding lead. Ensure that the current (amperage) capacity of
the grounding lead will be adequate for the worst fault current situation. Refer to the National ElectricalCode
ANSI/NFPA 70 for details. Do not remove plug ground prongs. Use correctly mating receptacles.

2. Output Cables and Terminals

Inspect cables frequently for damage to the insulation and the connectors. Replace or repair cracked or
worn cables immediately. Do not overload cables. Do not touch output terminal while equipment is energized.

3. Service and Maintenance

This equipment must be maintained in good electrical and mechanical condition to avoid hazards stem­ming from disrepair. Report any equipment defect or safety hazard to the supervisor and discontinue use of
the equipment until its safety has been assured. Repairs should be made by qualified personnel only.

Before inspecting or servicing electrically-powered equipment, take the following precautions:

a. Shut OFF all power at the disconnecting switch or line breaker before inspecting or servicing the
equipment.

b. Lock switch OPEN (or remove line fuses) so that power cannot be turned on accidentally.
c. Disconnect power to equipment if it is out of service.
d. If troubleshooting must be done with the unit energized, have another person present who is trained in

turning off the equipment and providing or calling for first aid.

C . FIRE AND EXPLOSION PREVENTION

Fire and explosion are caused by electrical short circuits, combustible material near engine exhaust pip­ing, misuse of batteries and fuel, or unsafe operating or fueling conditions.

1. Electrical Short Circuits and Overloads

Overloaded or shorted equipment can become hot enough to cause fires by self destruction or by causing
nearby combustibles to ignite. For electrically-powered equipment, provide primary input protection to remove
short circuited or heavily overloaded equipment from the line.

2. Batteries

Batteries may explode and/or give off flammable hydrogen gas. Acid and arcing from a ruptured battery
can cause fires and additional failures. When servicing,do not smoke, cause sparking, or use open flame
near the battery.

3. Engine Fuel

Use only approved fuel container or fueling system. Fires and explosions can occur if the fuel tank is not
grounded prior to or during fuel transfer. Shut unit DOWN before removingfueltank cap. DO NOT com­pletely fill tank, because heat from the equipment may cause fuel expansion overflow. Remove all spilled fuel
IMMEDIATELY, including any that penetrates the unit. After clean-up, open equipment doors and blowfumes
away with compressed air.

D. TOXIC FUME PREVENTION

Carbon monoxide - Engine exhaust fumes can kill and cause health problems. Pipe or vent the exhaust
fumes to a suitable exhaust duct or outdoors. Never locate engine exhausts near intake ducts of air condition­ers.

E. BODILY INJURY PREVENTION

Serious injury can result from contact with fans inside some equipment. Shut DOWN such equipment for
inspection and routine maintenance. When equipment is in operation, use extreme care in doing necessary
trouble-shooting and adjustment. Do not remove guards while equipment is operating.

F. MEDICAL AND FIRST AID TREATMENT

First aid facilities and a qualified first aid person should be available for each shift for immediate treat­ment of all injury victims. Electric shock victims should be checked by a physician and taken to a hospital im­mediately if any abnormal signs are observed.

EMERGENCY FIRST AID

Call physician immediately. Seek additional assistance. Use First Aid techniques recommended
by American Red Cross until medical help arrives.

IF BREATHING IS DIFFICULT, give oxygen, if available, and have victim lie down. FOR ELECTRI­CAL SHOCK, turn off power. Remove victim; if not breathing, begin artificial respiration, preferably
mouth-to-mouth. If no detectable pulse, begin external heart massage. CALL EMERGENCY RESCUE
SQUAD IMMEDIATELY.

G. EQUIPMENT PRECAUTIONARY LABELS

Inspect all precautionary labels on the equipment monthly. Order and inspect all labels that cannot be
easily read.

OM-2029

LIST OF EFFECTIVE PAGES

CHAPTER/ CHAPTER/

SECTION PAGE DATE SECTION PAGE DATE

List of 1 Mar 16/90 1-3 1 Sept 30/89

Effective 2 Mar 16/90 1-3 2 Sept 30/89

Pages 1-3 3 July 27/90

1-3 4 July 27/90

Introduction 1/2 Sept 30/89 1-3 5 Sept 30/89

1-3 6 July 27/90
Contents 1 Sept 30/89 1-3 7 July 27/90
Contents 2 Sept 30/89 1-3 8 Sept 30/89
Contents 3 Sept 30/89
Contents 4 Sept 30/89 2-1 1 Sept 30/89
Contents 5 Sept 30/89 2-1 2 Sept 30/89
Contents 6 Sept 30/89 2-1 3 Sept 30/89
Contents 7 Sept 30/89 2-1 4 Sept 30/89
Contents 8 Sept 30/89 2-1 5 Sept 30/89
Contents 9 Sept 30/89 2-1 6 Sept 30/89
Contents 10 Sept 30/89 2-1 7 Sept 30/89
Contents 11 Sept 30/89 2-1 8 Sept 30/89
Contents 12 Sept 30/89 2-1 9 Sept 30/89

2-1 10 Sept 30/89
1-1 1 July 27/90 2-1 11 Sept 30/89
1-1 2 Sept 30/89 2-1 12 Sept 30/89
1-1 3 Mar 16/90 2-1 13 Sept 30/89
1-1 4 Mar 16/90 2-1 14 Sept 30/89
1-1 5 July 27/90
1-1 6 July 27/90 2-2 1 Sept 30/89
1-1 7 Sept 30/89 2-2 2 Sept 30/89
1-1 8 Sept 30/89 2-2 3 Sept 30/89
1-1 9 Sept 30/89 2-2 4 Sept 30/89
1-1 10 Sept 30/89 2-2 5 Sept 30/89
1-1 11 Sept 30/89 2-2 6 Sept 30/89
1-1 12 Sept 30/89
1-1 13 Sept 30/89 2-3 1 July 27/90
1-1 14 July 27/90 2-3 2 Sept 30/89
1-1 15 July 27/90 2-3 3 July 27/90
1-1 16 July 27/90 2-3 4 July 27/90
1-1 17 July 27/90 2-3 5 Sept 30/89
1-1 18 Sept 30/89 2-3 6 Sept 30/89
1-1 19 Sept 30/89 2-3 7 Sept 30/89
1-1 20 Sept 30/89 2-3 8 Sept 30/89
1-1 21 Sept 30/89 2-3 9 Mar 16/90
1-1 22 Sept 30/89 2-3 10 Mar 16/90
1-1 23 Sept 30/89 2-3 11 Mar 16/90
1-1 24 Sept 30/89 2-3 12 Mar 16/90

2-3 13 Mar 16/90
1-2 1 Sept 30/89 2-3 14 Mar 16/90
1-2 2 Sept 30/89
1-2 3 Sept 30/89
1-2 4 Sept 30/89

July 27/90 Revised List of Effective Pages

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LIST OF EFFECTIVE PAGES (CONTINUED)

CHAPTER/ CHAPTER/
SECTION PAGE DATE SECTION PAGE DATE

3-1 1 Sept 30/89 4-3 8 Sept 30/89
3-1 2 Sept 30/89 4-3 9 July 27/90
3-1 3 Sept 30/89 4-3 10 Sept 30/89
3-1 4 Sept 30/89 4-3 11 Sept 30/89
3-1 5 July 27/90 4-3 12 Sept 30/89
3-1 6 Sept 30/89 4-3 13 Sept 30/89
3-1 7 Sept 30/89 4-3 14 Sept 30/89
3-1 8 Sept 30/89 4-3 15 Sept 30/89
3-1 9 Sept 30/89 4-3 16 Sept 30/89
3-1 10 Sept 30/89 4-3 17 July 27/90
3-1 11 Sept 30/89 4-3 18 July 27/90
3-1 12 Sept 30/89 4-3 19 July 27/90
3-1 13 Sept 30/89 4-3 20 Sept 20/89
3-1 14 Sept 30/89 4-3 21 July 27/90
3-1 15 July 27/90 4-3 22 Sept 30/89
3-1 16 July 27/90 4-3 23 Sept 30/89
3-1 17 July 27/90 4-3 24 Sept 30/89
3-1 18 July 27/90 4-3 25 July 27/90
3-1 19 Sept 30/89 4-3 26 Sept 30/89
3-1 20 July 27/90 4-3 27 Sept 30/89
3-1 21 Sept 30/89 4-3 28 Sept 30/89
3-1 22 Sept 30/89 4-3 29 July 27/90
3-1 23 Sept 30/89 4-3 30 July 27/90
3-1 24 Sept 30/89 4-3 31 July 27/90
3-1 25 Sept 30/89 4-3 32 Sept 30/89
3-1 26 Sept 30/89 4-3 33 July 27/90
3-1 27 Sept 30/89 4-3 34 Sept 30/89
3-1 28 Sept 30/89 4-3 35 July 27/90

4-3 36 Mar 16/90
4-1 1 July 27/90 4-3 37 July 27/90
4-1 2 Mar 16/90 4-3 38 Mar 16/90

4-3 39 July 27/90
4-2 1 Sept 30/89 4-3 40 July 27/90
4-2 2 Mar 16/90 4-3 41 July 27/90
4-2 3 Mar 16/90 4-3 42 July 27/90
4-2 4 Mar 16/90 4-3 43 July 27/90

4-3 44 July 27/90
4-3 1 Sept 30/89
4-3 2 Sept 30/89 5-0 1 July 27/90
4-3 3 Sept 30/89 5-0 2 Sept 30/89
4-3 3A July 27/90
4-3 3B July 27/90 6-0 1 July 27/90
4-3 3C July 27/90 6-0 2 Sept 30/89
4-3 3D July 27/90
4-3 4 Sept 30/89
4-3 5 Mar 16/90
4-3 6 Mar 16/90
4-3 7 July 27/90

List of Effective Pages July 27/90 Revised
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Table of Contents

WARNING

LIST OF EFFECTIVE PAGES
INTRODUCTION

SUBJECT CHAPTER/SECTION PAGE

CHAPTER 1. DESCRIPTION/OPERATION

SECTION 1. DESCRIPTION 1-1 1

1. General 1-1 1

2. Orientation 1-1 1

3. Special Features 1-1 1

A.Protective Monitor 1-1 1
B.Voltage Regulator 1-1 1
C. Dual Outputs 1-1 3
D. Electric Governor 1-1 3
E. Hinged Front Panel on Generator

Control Box 1-1 3

4. Identification 1-1 5

5. Optional Equipment 1-1 6

A. Trailer 1-1 6
B. Transformer-Rectifier (6906-3 and

6906-4 ONLY) 1-1 6
C. Truck 1-1 6
D. Quick Start Kit 1-1 6

6. Canopy 1-1 6

7. Engine, Generator, and Controls
Assembly 1-1 6

A. Basic Engine 1-1 6
B. Engine Manufacturer’s Equipment 1-1 7
C. Hobart Engine Equipment 1-1 7

(1) Electric governor system 1-1 7

(a) Magnetic pickup 1-1 7
(b) Control unit 1-1 7
(c) Actuator 1-1 7

(2) Engine electrical system 1-1 7
(3) Engine protective devices 1-1 9
(4) Air cleaner 1-1 9
(5) Water Temperature Sender 1-1 10
(6) Oil Pressure Sender 1-1 10
(7) Exhaust system 1-1 10
(8) Radiator 1-1 10

D. Generator 1-1 11

September 30/89 Revised Table of Contents

Page 1

OM-2029

SUBJECT CHAPTER/SECTION PAGE

E. Control Box Assembly 1-1 11

(1) Generator Control Box Front Panel

Components 1-1 12

(a) Generator output monitors (meters) 1-1 12
(b) Meter and line switches 1-1 12
(c) Indicating lights 1-1 12
(d) Load contactor circuit breaker 1-1 12
(e) Protective system circuit breaker 1-1 12

(2) Generator Control Box Interior Components

(Figure 7) 1-1 14

(a) Sensing modules 1-1 14
(b) Memory and time delay module 1-1 14
(c) Plug-interlock relays 1-1 15
(d) Test-bank switches 1-1 15
(e) Resistor 1-1 15
(f) Fuse-interlock relay 1-1 15
(g) Auxiliary underfrequency relay 1-1 15
(h) Regulated-diagnostic switch 1-1 15
(j) Excitation-deenergization relay 1-1 15
(k) Voltage Regulator 1-1 17

F. Engine Control Panel (See Fig. 9) 1-1 18

(1) Engine instruments 1-1 18
(2) Engine and generator controls 1-1 18

H. Power Module Panel Assembly 1-1 20

(1) Load contactor 1-1 21
(2) Current transformers 1-1 21
(3) Rectifiers 1-1 21
(4) Overload module 1-1 22
(5) Terminal boards 1-1 22

SECTION 2. PREPARATION FOR

USE, STORAGE, OR SHIPPING 1-2 1

1. Preparation for Use 1-2 1

A. General 1-2 1

B. Inspection/Check 1-2 1

(a) Fuel 1-2 1
(b) Engine coolant 1-2 1
(c) Engine lubricating oil 1-2 1

C. Installing Output Cables 1-2 2

2. Preparation for Storage 1-2 3

A. General 1-2 3
B. Temporary Storage 1-2 3
C. Long Time Storage (Over 30 Days) 1-2 3

Table of Contents September 30/89 Revised
Page 2

OM-2029

SUBJECT CHAPTER/SECTION PAGE

SECTION 3. OPERATION 1-3 1

1.General 1-3 1

2. Operating the Generator Set 1-3 1

A. Pre-start Inspection 1-3 1
B. Normal Engine Starting Procedures 1-3 1
C. Cold Weather Engine Starting Procedures 1-3 4
D. Preparation for Power Delivery

(Normal Automatic Voltage Control) 1-3 5

E. Power Delivery 1-3 5

No. 1 Output Circuit 1-3 5

No. 2 Output Circuit 1-3 6
F. Discontinue Power Delivery 1-3 6
K. Stopping the Engine 1-3 6

3. Transformer-Rectifier Operation 1-3 6

A. Direct Current Power Delivery 1-3 6
B. Simultaneous 28.5-V DC and

115-V AC Power Delivery 1-3 7

4. Trailer Operation (Optional) 1-3 8

A. Towing 1-3 8
B. Parking 1-3 8

CHAPTER 2. SERVICE

SECTION 1. MAINTENANCE 2-1 1

1. General 2-1 1

2. Inspection 2-1 1

3. Lubrication 2-1 1

A. General 2-1 1
B. Generator 2-1 1
C. Generator Controls 2-1 1
D. Engine 2-1 1

(1) Lubrication schedule 2-1 2

(2) Oil specification 2-1 2

(3) Oil viscosity 2-1 2

(4) Changing engine oil 2-1 2

(5) Changing engine oil filter 2-1 2
E. Starter 2-1 2

4. Air Cleaner Service 2-1 3

A. Cartridge Removal (See Fig. 2) 2-1 3
B. Cartridge Installation (See Fig. 2) 2-1 4

5. Engine Fuel 2-1 4

A. Quality 2-1 4
B. Fuel Filter 2-1 4

September 30/89 Revised Table of Contents

Page 3

OM-2029

SUBJECT CHAPTER/SECTION PAGE

6. Engine Cooling System 2-1 5

A. General 2-1 5
B. Radiator Cap 2-1 5

(1) General 2-1 5
(2) Removal 2-1 5

(3) Installation 2-1 5
C. Warm Weather Operation 2-1 5
D. Cold Weather Operation 2-1 5

(1) General 2-1 5

(2) Checking coolant solution 2-1 6

(3) Preparing the coolant solution 2-1 6

(4) Installing the antifreeze solution 2-1 6
E. Draining the Cooling System 2-1 6
F. Cleaning the Cooling System 2-1 7
G. Cleaning the Radiator Core 2-1 7
H. Filling the Cooling System 2-1 7

7. Generator Maintenance 2-1 8

A. Cleaning 2-1 8
B. Adjustment 2-1 8

8. Drive Belts 2-1 8

A. Checking Belt Tension 2-1 8
B. Belt Adjustment 2-1 8

9. Trailer and Truck Maintenance 2-1 9

A. General 2-1 9
B. Cleaniness 2-1 9
C. Grease application 2-1 9
D. Lubrication chart 2-1 9

2-1 10
E. Checking Wheel Bearings 2-1 12
F. Adjusting Wheel Bearings 2-1 12

10. Battery Service 2-1 12

A. General 2-1 12
B. Battery Location and Accessibility 2-1 12
C. Battery Care 2-1 12
D. Liquid Level 2-1 12
E. Cleaning the Battery 2-1 13

F. Testing the Battery 2-1 13

11. Service Helps 2-1 13

A. Wiring 2-1 13
B. Generator Exciter 2-1 13

SECTION 2. INSPECTION/CHECK 2-2 1

1. General 2-2 1

2. Engine 2-2 1

A. Fuel (See Fig. 1 for time schedules) 2-2 1
B. Lubrication 2-2 1
C. Coolant 2-2 1
D. V-Belts 2-2 1
E. Exhaust System 2-2 1

Table of Contents September 30/89 Revised
Page 4

OM-2029

SUBJECT CHAPTER/SECTION PAGE

3.Electrical System (12-V DC) 2-2 3

A. Lights 2-2 3
B. Circuit Breakers 2-2 3
C. Wiring and Connections 2-2 3

4. Electrical System (115-V AC) 2-2 4

A. Monitoring Instruments 2-2 4
B. Indicating Lights 2-2 4
C. Protective Modules 2-2 4
D. Wiring and Connections 2-2 4

5. Trailer and Truck 2-2 5

SECTION 3. ADJUSTMENT/TEST 2-3 1

1. General 2-3 1

2. Generator Set Test 2-3 1

A. Pre-operational Test Procedures 2-3 1
B. Operational Test Procedures 2-3 1

3. Generator Set Adjustment 2-3 8

A. Generator Adjustment 2-3 8
B. Generator Control Adjustments 2-3 8
C. Basic Engine Adjustments 2-3 9
D. Engine Accessories Adjustment 2-3 9
E. Electric Governor System Adjustment 2-3 9

(1) Actuator linkage adjustment 2-3 9
(2) Magnetic pickup adjustment 2-3 11
(3) Governor Control Unit Adjustment 2-3 12

5. Generator and Exciter Test 2-3 14

6. Diode Test 2-3 14

CHAPTER 3. TROUBLESHOOTING

SECTION 1. TROUBLESHOOTING

PROCEDURES 3-1 1

1. General 3-1 1

2. Troubleshooting Chart 3-1 1

3. Equipment for Troubleshooting 3-1 2

4. Safety 3-1 2

5. Parts Replacement 3-1 2

6. Test Values 3-1 2

7. Checking Connections and Leads 3-1 3

8. Electric Governor Troubleshooting 3-1 3

9. Engine Troubleshooting Procedures 3-1 3

A. General 3-1 3

September 30/89 Revised Table of Contents

Page 5

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SUBJECT CHAPTER/SECTION PAGE

CHAPTER 4. ILLUSTRATED PARTS LIST

SECTION 1. INTRODUCTION 4-1 1

1. General 4-1 1

2. Purpose 4-1 1

3. Arrangement 4-1 1

4. Explanation of Parts List 4-1 1

A. Contents 4-1 1
B. Parts List Form 4-1 2

(1) FIGURE-ITEM NO. Column 4-1 2
(2) HOBART PART NUMBER Column 4-1 2
(3) NOMENCLATURE Column 4-1 2
(4) REC. SPARES Column 4-1 2
(5) “EFF” (Effectivity) Column 4-1 2
(6) UNITS PER ASSEMBLY Column 4-1 2

SECTION 2. MANUFACTURERS’

CODES 4-2 1

1. Explanation of Manufacturers’
(Vendors’) Code List 4-2 1

SECTION 3. PARTS LIST 4-3 1

1. Explanation of Parts List Arrangement 4-3 1

2. Symbols and Abbreviations 4-3 1

SECTION 4. NUMERICAL INDEX

1. Explanation of Numerical Index 4-3 1

CHAPTER 5. OPTIONAL EQUIPMENT

CHAPTER 6. MANUFACTURERS’ LITERATURE

UNUSUAL SERVICE CONDITIONS

Table of Contents September 30/89 Revised
Page 6

Addendum to

Operation and Maintenance Manual OM-2029

covering a Modification to

Generator Set Specifications 6906-2 and 6906-4

1. Scope

This addendum increases the coverage of Hobart Manual OM-2029 to include a modification to Gene- ra­tor Set Specification Numbers 6906-2 and 6906-4
erator set is equipped with a battery that is installed in the engine compartment of the generator set,
rather than in a compartment on the truck.

(truck-mounted units).

(See Figure 1).

As per this modification, the gen-

2. Description

In regard to physical appearance, electrical output ratings, and operation, the Specification 6906-2 or
6906-4 generator set with the aforementioned modification, as covered by this addendum, is identical to
all other Specification 6906-2 or 6906-4 generator sets.

OM-2029

Figure 2 is an illustration that shows the various components of the inboard battery kit, which is identified
as Hobart Part No. 281926. This illustration is accompanied by a parts list whose item numbers corre­spond with the call-out numbers on the illustration.

June 6/90 Addendum

Location of Inboard Battery

Figure 1

Page 1

OM-2029

Inboard Battery Kit

Part No. 281926

Figure 2

FIGURE HOBART PER
ITEM NO. PART NO. 1234567 EFF ASSY

2- 281926 BATTERY INSTALLATION

1 281871-1 . BATTERY, 12 VOLTS 1
2 281927 . SUPPORT, BATTERY 1
3 181831 . FRAME, HOLD-DOWN, BATTERY 1
4 481209-4 . CABLE, POSITIVE 1
5 383067-5 . CABLE, NEGATIVE 1

6 5CW-2048 . ROD, BATTERY, SUPPORT, ASSY 2

Addendum June 6/90
Page 2

NOMENCLATURE UNITS

(For units having ONE battery) REF

3. Customer Service

If you have any questions concerning your Hobart Ground Airport Systems Group equipment, you are in­vited to contact our service department by mail, telephone, or FAX.

Write: Hobart Brothers Company

Airport Systems Group
1177 Trade Road East
Troy, Ohio 45373, U.S.A.

Telephone: [phone] (Service Assistance)

[phone] (Parts Replacement)

FAX: [phone]

OM-2029

June 6/90 Addendum

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Addendum June 6/90
Page 4

OM-2029

CHAPTER 1. DESCRIPTION/OPERATION

SECTION 1. DESCRIPTION

1. General

Generator sets
rations of the set are identified by adding a dash number
6906 generator sets feature armatures with Hoover Bearings, Browning Coupler, and different magnetic
pole construction for the generator revolving field.

The basic generator set which includes the engine, generator and all controls is identical for all models.
Differences between models are those required by their respective mountings, such as trailer mounting,
truck mounting, etc., or by other special features. Identificationof different models within the Series will be
explained later in the Description. Information and instructions throughout the manual apply to all models.
Information which applies only to a certain model will be qualified and identified as such.

The purpose of the generator set is to generate and deliver regulated, 400-Hz electrical power to a parked

(or towed)

running. The engine, generator, and controls are designed into a compact unit which is easily removable
from a tow tractor. See Figure 2 for specifications and capabilities.

(see Fig. 1)

aircraft for operation of the aircraft’s electrical equipment when the on-board generators are not

covered by the manual are identified by Series No. 6906. The various configu-

(-1, -2, etc.)

suffix to the Series number. Series

2. Orientation

For purpose of orientation and to familiarize operators and maintenance personnel with the location of
components, the radiator is considered to be at the FRONT of the unit. The generator and controls are at
the REAR. RIGHT and LEFT are determined by standing at the rear end facing the machine. Thus, the
generator controls are mounted on the REAR of the unit.

3. Special Features

The generator set has many special features which are later described more fully under the assemblies in
which they appear. Some of the main features are mentioned here and described briefly.

A. Protective Monitor

A single, solid-state device
ator output circuit and functions to cause the load to be disconnected from the generator if an abnor­mal condition of voltage, frequency, or load develops.

B. Voltage Regulator

A solid-state, adjustable voltage regulator
6906-1 and 6906-2 generator sets. This voltage regulator provides automatic voltage regulation at
the aircraft
cable sizes and lengths. A magnetic amplifier type voltage regulator
used on Specification 6906-3, Specification 6906-4, Specification 6906-5 and Specification 6906-6
generator sets. This regulator is also adjustable for a variety of output cable sizes and lengths.

July 27/90 Revised 1-1

(or distribution panel when applicable)

(4, Fig. 8)

receives signals from all of the fault sensing units in the gener-

(Hobart part number 489812A)

. This regulator is adjustable for a variety of output

is used on Specification

(Hobart part no. 281407)

is

Page 1

OM-2029

1. Canopy 5. Engine fan exhaust vent

2. Lifting eye 6. Engine exhaust pipe

3. Windows 7. Radiatorcap

4. Mounting frame

1-1 September 30/89 Revised
Page 2

Generator Set

(without trailer)

Figure 1

OM-2029

Generator Set Mounted on Fifth-Wheel Trailer

Figure 1A

C. Dual Outputs

Each generator set is equipped with two output circuits and dual controls so that power may be deliv­ered to an aircraft requiring two inputs, or to one or two aircraft with single input requirements.

D. Electric Governor

The engine is equipped with an all electric type governor kit
ment more fully described under the engine description.

E. Hinged Front Panel on Generator Control Box

The control box is equipped with a hinged front panel. Located conveniently on this panel are
switches, meters, indicator lights, and circuit breakers for controlling and monitoring the generator.
This panel swings out to provide easy access to the voltage regulator, PC boards, and relays which
are used to control and monitor the generator.

(9and 15, Fig. 3)

and other special equip-

March 16/90 Revised 1-1

Page 3

OM-2029

PHYSICAL

BASIC UNIT

Length overall 109.6 inches
Width 45.5 inches
Height overall 62.0 inches
Weight 3500 pounds

FOUR-WHEEL TRAILER-MOUNTED UNIT

Length overall 119.0 inches
Width 80.0 inches
Height 79.0 inches
Weight 5400 pounds

FIFTH-WHEEL TRAILER MOUNTED UNIT

Length overall, with tongue up 160 inches
Length overall, with tongue down 228 inches
Width 84 inches
Height 84 inches
Weight

(with 1/4 tank of fuel

and no cables)

7160 pounds

GENERATOR

Output power rating 140 KVA
Output voltage 115/200 V
Rated load capacity 404 Amp
Frequency
Output kilowatts 112 KW
Power factor 0.8 PF
Duty cycle 100%
Operating speed at 400 Hz 1714 RPM
Overload capacity 505 Amp

(125% of rated load capacity)

(cycles-per-second)

400 Hz

(2784 mm)
(1156 mm)
(1575 mm)

(1496.8 kg)

(3023 mm)
(2032 mm)
(2007mm)

(2358.7 kg)

(4064 mm)

(5791 mm)
(2134 mm)
(2134 mm)

(3247 kg)

GENERATOR PROTECTIVE SYSTEM

Overvoltage relay trips 130 V to 134 V; resets 125 V
Undervoltage relay trips 102 V or below; resets 110 V
Overfrequency relay trips 415 Hz to 425 Hz; resets 410 Hz
Underfrequency relay trips 375 Hz to 385 Hz; resets 385 Hz
Overload relay trips 175 KVA in less than 5 minutes
Undervoltage time delay relay 4 to 12 seconds

1-1 August 15/90 Revised
Page 4

OM-2029

ENGINE

Manufacturer John Deere
Model 6466T
Type Turbocharged, In-line, 6-cylinder,

4-cycle Diesel
Displacement 466 cu. in. (7.64 liters)
Compression ratio 15.8:1
Firing order 1-5-3-6-2-4
Horsepower at 2000 RPM 250
Governed speed 1714 RPM
Idle speed 850 RPM +/- 25 RPM
Electrical system 12 volt
Oil capacity (with filter) 18 quarts (14 liters)
Oil capacity (without filter) 16quarts (13.6 liters)
Coolant capacity (approx.) 12.44 gallons (47.0 liters)
Fuel Diesel oil conforming to ASTM Spec.

D.975-66T, Nos. 1-D and 2-D
Lube oil MIL-L-2104C or MIL-L-2104D

Specifications and Capabilities

Figure 2 (Sheet 2 of 2)

4. Identification

Generator sets are identified by their Specification number which consists of the Series number plus a
dash number
other major feature(s) of the generator set.

SPECIFICATION MOUNTING DESCRIPTION

6906-1 Trailer Basic generator set in Series 6906, having a fuel tank,

6906-2 Truck Basic generator set in Series 6906, similar to Spec

6906-3 5th-Wheel Trailer Has provisions for transformer-rectifier (T-R). Also

6906-4 Truck Similar to Spec 6906-2, except that it has magnetic

6906-5 5th-Wheel Trailer Similar to Spec 6906-1, except for the trailer, and this

(i.e. -1, -2, etc.)

suffix. The suffix number indicates either the mounting design and/or some

battery, plus a tray for battery and cables.

6906-1, except for mounting.

has fuel tank and battery, plus tray for cable and

battery.

amplifier type voltage regulator, Hobart Part No. 281407

unit DOES NOT have a fuel tank, battery, or a tray
for battery and cables. Special for SIA.

6906-6 5th-Wheel Trailer Similar to Spec 6906-5, with fuel tank, cable tray,

July 27/90 Revised 1-1

battery/cable tray, rear fenders, and rear bumper

Page 5

OM-2029

5. Optional Equipment

Several items of optional equipment are available for the 6906 Series units. When applicable, information
for optional equipment will be located in Chapter 5.

A. Four-Wheel Trailer (Specification 6906-1)

This is a standard four wheel trailer, used on earlier Series 6906 generator set models, and identified
by Hobart Part No. 408595.

B. Fifth-Wheel Trailer

A trailer with fifth-wheel front running gear is available, with or without batteries and fuel tank. This
trailer with fifth-wheel replaces the previously used four wheel trailer, and reduces greatly the turning
radius when the unit is being towed.

B. Transformer-Rectifier (Specifications 6906-3, 6906-4, 6906-5, and 6906-6)

A transformer-rectifier
6 generator sets. This T-R receives 115/200-V, 400-Hz, AC power from the generator and converts it
to a 28.5 V DC output. Additionally, Specifications 6906-5 and 6906-6 may be equipped with a sec­ond T-R, with rated output of either 28.5V or 112 V.

C. Truck

Trucks with special bodies for mounting the generator set are available. Compartments in the body
are provided for batteries, cable-storage, etc. Trucks available are Ford, Chevrolet, and GMC.

D. Quick Start Kit

(T-R)

is available for use with Specifications 6906-3 ,6906-4, 6906-5 and 6906-

(See Section 1-3, Para. 2C)

6. Canopy

A sheet metal enclosure, identified as a canopy
and electrical controls. The canopy is designed to reduce operational noise in the immediate area of the
machine. Four hinged doors on the left side provide easy access for service and maintenance. Two
hinged doors near the front on the right side provideaccess to the engine compartment. Panel mounted
instruments may be observed through two Plexiglass windows which cover a portion of the control box
and the engine control panel. The lower window is slanted outward at the bottom to provide an opening
for reaching engine controls. A small panel located below the air cleaner covers the dual output terminal
board.

(1, Fig. 1),

provides protection for the engine, generator

7. Engine, Generator, and Controls Assembly

This assembly is the basic generator set without canopy. It includes all components required to generate
and regulate 400 Hz, 115/200 V, three phase power, and is operable when provided with fuel and 12 V
DC power. The engine-generator assembly is mounted on a welded steel frame. A superstructure, at­tached to the main frame, provides mounting facilities for the canopy, control box, electrical equipment
and controls.

A. Basic Engine

This generator set is equipped with a 6-cylinder, in-line, turbo-charged John Deere Diesel engine. See
Figure 2 for general specifications, and see Engine Operator’s Handbook in Chapter 6 for more de­tailed information.

1-1 July 27/90 Revised
Page 6

B. Engine Manufacturer’s Equipment

As received from the engine manufacturer, the engine includes the following equipment which is de­scribed in the John Deere Shop Manual

(1) Fuel filter.
(2) Reverse-flow, engine cooling fan to blow air outward through the radiator.

C. Hobart Engine Equipment

The engine is modified at Hobart Brothers by the addition of the following equipment:

(1) Electric governor system

An electric governor kit is installed on the engine to replace a conventional, mechanical type. The
electric governor was selected for control of engine speed
cause it provides faster engine response to changes in load conditions. This fast response results
in very close frequency control. Refer to the Woodward instruction booklet in C hapter 6 for a de­tailed description. A brief description is given below:

The governor system consists of the following main components:

Magnetic pickup

(Chapter 6)

.

(and generator output frequency)

OM-2029

be-

Control unit
Actuator

(a) Magnetic pickup

The magnetic pickup is a device for detecting the speed of the engine. It is mounted in the fly­wheel housing directly over the ring gear. It produces an AC signal to the control unit when
the ferrous flywheel teeth pass through the magnetic field at the end of the pickup.

(b) Control unit

The control unit
It receives an AC signal from the magnetic pickup and senses speed changes in the engine.
It provides a voltage signal to the actuator which causes the actuator to move the fuel control
lever as required to maintain a predetermined engine speed. Its power is received from the
12-V DC battery system.

(c) Actuator

The actuator
quired to maintain a constant engine speed. The actuator is operated by a DC signal from the
control unit.

(2) Engine electrical system

Items in the 12-volt engine electrical system that are provided by Hobart Brothers are:
(a) A heavy-duty motor starter

(9,Fig.3)

(15 Fig. 3)

is a box containing a compact assembly of solid state components.

supplies the force needed to move and position the fuel lever as re-

(b) Alternator with voltage regulator
(c) Starting switch
(d) Wiring harness

September 30/89 Revised 1-1

Page 7

OM-2029

1. Radiator 8. Generator Control Box 15. Actuator, Governor

2. Fan Guard 9. Control Box, Governor 16. Lube Oil Pressure Switch

3. Muffler & Exhause Pipe 10. Power Module Panel 17. Lube Oil Pressure Sensor

4. Diesel Engine 11. Generator Assembly 18. High Engine Temperature

5. Lifting Eye 12. Frame Switch

6. Lifting Yoke 13. Engine Control Panel 19. Water Temperature Sensor

7. Air Cleaner 14. Output Terminal Panel

1-1 September 30/89 Revised
Page 8

Generator Set Components

Figure 3

(3) Engine protective devices

(a) High coolant temperature switch

OM-2029

A high coolant temperature switch
the coolant temperature. If the coolant temperature reaches 210 degrees F
this normally closed switch opens and actuates the fuel valve solenoid which shuts down the
engine.

(b) Oil pressure switch

A diaphragm-type switch monitors the pressure in the lubricating oil system. It is mounted in
the side of the cylinder block

(69 kPa)

(4) Air cleaner

The diesel-engine air cleaner
tor and a service indicator. The indicator functions to signal the operator when the cartridgeneeds
changing. A red cylindrical “flag”
when air pressure within the air cleaner housing drops below the outside air pressure. As the car­tridge becomes loaded with dirt and air pressure withinthe cleaner lessens, the “flag” gradually
rises higher in the glass viewing chamber. When the “flag” reaches the top of the chamber, it
locks in that position to warn the operator that the cartridge must be changed. The “flag” is reset

(unlocked)

, this switch opens and actuates the fuel valve solenoid which shuts down the engine.

(Fig. 4)

by pushing the reset button

(18, Fig. 3)

is mounted at the rear of the engine to monitor

(99 degrees C)

(16, Fig. 3)

(2)

is forced upward in a glass enclosed viewing chamber

. If the pressure in the lube oil system falls to 10 psi

is a dry-cartridge type. It is equipped with a moisture elimina-

(3)

located on the bottom of the indicator.

(1)

NOTE: The service indicator is mounted on the engine control panel and connected to the air cleaner
by a rubber hose. The indicator flag is visible only when the engine is running, or when the flag islocked
in WARNING position.

,

September 30/89 Revised 1-1

1. Viewing chamber

2. Indicating “flag”

3. Reset button

Air Cleaner and

ServiceIndicator

Figure 4

Page 9

OM-2029

(5) Water Temperature Sender

The water temperature sender
actuates the temperature gage

(6) Oil Pressure Sender

The oil pressure sender
senses oil pressure and operates the oil puressure gage

(7) Exhaust system

The exhaust system consists of a special noise reducing muffler

(1)

apipe
ward.

(8) Radiator

The radiator
ing. Refer to Section 2-1, Para. 6, G, for servicing procedure.

to a conventional exhaust manifold. The tail pipe

(1, Fig. 3)

is a one-piece item designed for long periods of operation without servic-

(19, Fig. 3)

(5, Fig. 9)

(17, Fig. 3)

is mounted at the top rear of the engine. This device

on the engine control panel.

is mounted at the right lower rear of the engine. This device

(4, Fig. 9)

(3)

on the engine control panel.

(2, Fig. 5)

directs exhaust and noise down-

which is connected by

1-1 September 30/89 Revised
Page 10

1. Pipe, manifold­to-muffler

2. Muffler

3. Exhaust Pipe

Exhaust System

Figure 5

OM-2029

D. Generator

The 400-Hz generator is a brushless, revolving field, three-phase, alternating current type. The rotor
assembly is mounted by two, permanently lubricated, sealed, ball bearings. The front bearing is sup­ported by the fan housing; the rear bearing is mounted in the exciter housing. Both of these housings
are attached to the main generator stator housing. The front end of the rotor shaft extends forward be­yond the rear bearing and into the exciter stator housing. The exciter rotor is mounted on this shaft ex­tension with a Woodruff key and is securedby a washer and 1/2"-13thd, cap screw. A rectifier with
six diodes is mounted on the exciter rotor and converts exciter AC output to DC for excitation of the
generator revolving fields. The exciter DC output to the generator fields, and consequently the gener­ator output, is controlled by the amount of DC voltage supplied to exciter fields by the static voltage
regulator. A centrifugal, radial-blade fan which is part of the hub and coupling assembly, draws cool­ing air over all internal windings. Air enters at the exciter end and is discharged at the drive end. The
complete generator is bolted to the engine flywheel housing.

E. Control Box Assembly

The control box
generator controls and monitoring equipment. Switches, meters, indicator lights, and circuit breakers
which control and help to monitor the generator are all mounted on the front panel of the c ontrol box.
This panel is hinged on the right side, and can swing open for access to the interior panel where the
generator PC board assemblies and relays are mounted. A shielded, instrument panel light is
mounted near the top of the control box front panel, to illuminate controls and instruments on the
panel.

(Fig. 6)

is a sheet metal enclosure which houses and provides mounting facilities for

Control Box

Figure 6

September 30/89 Revised 1-1

Page 11

OM-2029

(1) Generator Control Box Front Panel Components

(a) Generator output monitors (meters)

• Refer to Figure 7. The generatoroutput is monitored by three instruments; a frequency me­ter

(10),

a voltmeter
type, and indicates frequency of generator ouput alternating current in the range of 380 to
420 Hz
phase-to-neutral
the meter selector switch
scribed below. The voltmeter has a 3-1/2-inch face and the scale is graduated 0 to 300V.
The ammeter is also 3-1/2-inch size and is graduated 0 to 500A. Amperage value in each
of the three phases may be read on the ammeter by selecting the desired phase with
switch
of infinite ratio, which will operate the ammeter movement without damage. The ammeter
dial scale is graduated and numbered so that the pointer will indicate true load current
value rather than the meter movement current.

(b) Meter and line switches

• These switches provide a means of selecting and determining which phase of voltage and
current is indicated on the voltmeter and ammeter and whether the voltage is line-to-neutral
or line-to-line. The meter switch
the panel is marked and lettered to indicate the three functional positions of the meter
switch. When the knob is pointing straight down, the switch is OFF. The line switch
two-position, toggle switch used to select either line-to-neutral or line-to-line voltage to the
voltmeter. The nameplate is also marked to indicate the position of this switch.

(cycles per second).

(7).

Three ammeter current transformers lower ouput load current to a lesser value,

(12),

andanammeter

The voltmeter indicates generator ouput voltage in each

(A-N, B-N and C-N)

(7)

and the line selector switch

(7)

(13).

The frequency meter is a resonant-reed

or phase-to-phase

is a four-position, rotary type. Around the switch knob,

(A-B, B-C and C-A)

(8).

These switches will be de-

as selected by

(8)

is a

(c) Indicating lights

• The function of these lights
mal condition of overvoltage, underfrequency, etc., which caused the protective monitor
system to function. Each of the five lights is connected to an actuating circuit within the
memory and time delay module. When one of the circuits is activated, it turns on the appli­cable indicating light. The light will remain on until the reset switch
in the indicating lights may be tested by pressing switch

(d) Load contactor circuit breaker

• This 2-ampere circuit breaker

(e) Protective system circuit breaker

• This 2-ampere circuit breaker
overload.

(9, 11, 14, 15 and 16)

is to indicate, to the operator, the abnor-

(5)

is pushed. All lamps

(5).

(4)

protects the load contactors against overload.

(6)

protects the 12VDC protective monitor circuit against

1-1 September 30/89 Revised
Page 12