MT 600 Service Manual SM1317 199907

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Service

Manual

Division of General Motors Corporation P.O. Box 894 Indianapolis, Indiana 46206-0894

Allison

Allison T

Transmis

ransmission

sion

SM1317EN

AUTOMATIC MODELS

MT 640, MT(B) 643

MT 650, MT(B) 653

AUGUST 1996

REVISED 199907

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INTRODUCTION

NOTE: NOTE: This publication is revised periodically to

This publication is revised periodically to include improvements,include improvements, new models, special tools, and procedures. A revision

new models, special tools, and procedures. A revision is indicatedis indicated by letter suffix to the publication number. Check with your by letter suffix to the publication number. Check with your Allison Transmission service outlet for the currently applicable Allison Transmission service outlet for the currently applicable publication. Additional copies of this publication may be publication. Additional copies of this publication may be pur-chased from authorized Allison Transmission service outlets. chased from authorized Allison Transmission service outlets. Look in your telephone directory under the heading of Look in your telephone directory under the heading of Transmis-sions — Truck, Tractor, etc.

sions — Truck, Tractor, etc.

TRADEMARK USAGE TRADEMARK USAGE

The following trademarks are the property of the companies indicated: • Amojell® is a registered trademark of the Amoco Oil Company. • DEXRON® is a registered trademark of General Motors Corporation.

• Biobor® JF is the registered trademark for a biological inhibitor manufactured by U.S. Borax and Chemical Corporation.

• Dykem® is a registered trademark of the Dykem Company. • Loctite® is a registered trademark of the Loctite Corporation. • Teﬂon® is a registered trademark of the DuPont Corporation. • Permatex® is a registered trademark of the Loctite Corporation.

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W

WARNING

ARNING S,

S, CAUTIONS, AND N

CAUTIONS, AND N OTES

OTES

Three types of headings are used

Three types of headings are used in this manual to attract your attention:in this manual to attract your attention:

NOTE: NOTE:

is used when an operating procedure, practice, etc., is used when an operating procedure, practice, etc., is essential to highlight. is essential to highlight. WARNING! WARNING!

is used when an operating procedure, practice, is used when an operating procedure, practice, etc., which, if not

etc., which, if not correctly followed, could resultcorrectly followed, could result in personal injury or loss of life.

in personal injury or loss of life.

CAUTION: CAUTION:

is used when an operating procedure, practice, is used when an operating procedure, practice, etc., which, if not strictly observed, could result etc., which, if not strictly observed, could result in damage to or destruction of equipment. in damage to or destruction of equipment.

IT IS YOUR RESPONSIBILITY to be completely

IT IS YOUR RESPONSIBILITY to be completely familiar with the Warnifamiliar with the Warni ngs and ngs and Cau- Cau-tions described in this Service Manual. These Warnings and CauCau-tions advise against the tions described in this Service Manual. These Warnings and Cautions advise against the use of specific service methods that can result in personal injury, damage to the use of specific service methods that can result in personal injury, damage to the equip-ment, or cause the equipment to become unsafe. It is, however, important to understand ment, or cause the equipment to become unsafe. It is, however, important to understand that these Warnings and Cautions are not exhaustive. Allison Transmission could not that these Warnings and Cautions are not exhaustive. Allison Transmission could not possibly know, evaluate, and advise the service trade of all conceivable ways in which possibly know, evaluate, and advise the service trade of all conceivable ways in which service might be done or of the possible hazardous consequences of each way. service might be done or of the possible hazardous consequences of each way. Conse-quently, Allison Transmission has not undertaken any such broad evaluation. quently, Allison Transmission has not undertaken any such broad evaluation. Accord-ingly, ANYONE WHO USES A SERVICE PROCEDURE OR TOOL WHICH IS NOT ingly, ANYONE WHO USES A SERVICE PROCEDURE OR TOOL WHICH IS NOT RECOMMENDED BY ALLISON TRANSMISSION MUST first be thoroughly satisfied RECOMMENDED BY ALLISON TRANSMISSION MUST first be thoroughly satisfied that neither personal safety nor equipment safety will be jeopardized by the service that neither personal safety nor equipment safety will be jeopardized by the service methods selected.

methods selected.

Proper service and repair are important to the

Proper service and repair are important to the safe, reliable operation of the equipment.safe, reliable operation of the equipment. The service procedures recommended

The service procedures recommended by Allison Tby Allison Transmission and described in ransmission and described in this Ser-this Ser-vice Manual are effective methods for performing serSer-vice operations. Some of these vice Manual are effective methods for performing service operations. Some of these ser-vice operations require the use of tools speciﬁcally designed for the purpose. The special vice operations require the use of tools speciﬁcally designed for the purpose. The special tools should be used when and as recommended.

tools should be used when and as recommended.

IMPORT

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LIST

LIST OF W

OF WARNIN

ARNIN GS

GS

This manual c

This manual c ontains the following Warontains the following War nings —nings —

IT IS YOUR RESPONSIBILITY TO BE FAMILIAR WITH ALL OF THEM. IT IS YOUR RESPONSIBILITY TO BE FAMILIAR WITH ALL OF THEM.

•• When checWhen checking the tking the transmiransmission fssion fluid leluid level, be suvel, be sure that thre that the parking be parking brake and/ rake and/ or emergency brakes are set and properly engaged, and the wheels are blocked. or emergency brakes are set and properly engaged, and the wheels are blocked. Unexpected and possible sudden movement may occur if these precautions are Unexpected and possible sudden movement may occur if these precautions are not taken.

not taken.

•• While coWhile conductinducting a stalng a stall check, thl check, the vehicle vehicle must be poe must be positisitively prevvely prevented frented fromom moving. Apply the parking and service brake, and block the wheels securely. moving. Apply the parking and service brake, and block the wheels securely. Warn personnel to keep clear of the vehicle and its travel path. Failure to do so Warn personnel to keep clear of the vehicle and its travel path. Failure to do so can cause serious injury.

can cause serious injury. •• Do nDo not ot burn burn disdiscardcarded Ted Tefleflonon

® ®

seals; toxic gases are produced by burning. seals; toxic gases are produced by burning. •• Never dry beNever dry bearings warings with compith compresseressed air. A spid air. A spinning beanning bearing can diring can disintsintegrateegrate

allowing balls or rollers to become lethal flying projectiles. Also, spinning a allowing balls or rollers to become lethal flying projectiles. Also, spinning a bearing without lubrication can damage the bearing.

bearing without lubrication can damage the bearing.

•• Do not positDo not position the tranion the transmissmission so thasion so that its rear end is lot its rear end is lo wer than itwer than its front end.s front end. The components in the rear of the transmission are not secured. These The components in the rear of the transmission are not secured. These

components could fall out and cause personal injury and/or damage to the parts. components could fall out and cause personal injury and/or damage to the parts. •• CertaiCertain contron control valve l valve body combody componentponents are sps are spring-lring-loaded and oaded and must bmust bee

restrained while retaining pins or bolts are removed. restrained while retaining pins or bolts are removed.

•• The main-The main-pressure compression.compression.pressure regulator varegulator valve sprilve spring is ng is under approximunder approximately 65 ately 65 lbs (29lbs (290 kN)0 kN) •• HydraulHydraulic fluiic fluid under 40 psi (d under 40 psi (280 kPa) pr280 kPa) pressure messure may be trappay be trapped in the oued in the outputtput

retarder accumulators. Personal injury can occur if this pressure is accidently retarder accumulators. Personal injury can occur if this pressure is accidently released.

released.

•• AccumulAccumulator pistator piston springon springs are highly coms are highly com presspressed. Use extreed. Use extreme cautime caution duringon during removal of the accumulator cover. Personal injury can occur if the bolts are removal of the accumulator cover. Personal injury can occur if the bolts are removed without properly relieving the spring force.

removed without properly relieving the spring force.

•• The retarThe retarder pistder piston returon return spring in spring is highls highly compresy compressed. Ussed. Use extreme extreme cautione caution during removal of the spring. Personal injury can occur if proper removal during removal of the spring. Personal injury can occur if proper removal procedures are not followed.

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Paragraph Page Paragraph Page

MT(B) 640, 643, 650, 653 AUTO MATIC TRANSMISSIONS

Section 1. GENERAL INFORMATION 1–1. SCOPE OF MANUAL a. Coverage. . . . . . .1–1 b. Illustrations . . . .1–1 c. Maintenance Information . . . .1–1 1–2. SUPPLEMENTARY INFORMATION . . . .1–1 1–3. ORDERING PARTS a. Transmission Nameplate . . . .1–1 b. Parts Catalog. . . .1–1 1–4. GENERAL DESCRIPTION a. Number of Speeds . . . .1–1 b. Torque Converter and Lockup Clutch . . .1–1 c. Planetary Gearing, Clutches . . . .1–6 d. Output Retarder . . . .1–6 1–5. OPERATING INSTRUCTIONS . . . .1–6 1–6. SPECIFICATIONS AND DATA . . . .1 –6

Section 2. DESCRIPTION AND OPERATION 2–1. SCOPE . . . .2–1 2–2. DESIGNATION OF CLUTCHES AND

PLANETARY GEAR SETS

a. Clutch Designations . . . .2–1 b. Planetary Gear Set Designations . . . .2–1 2–3. MOUNTING

a. To Engine . . . .2–1 b. To Vehicle . . . .2–1 c. Output Retarder Mount. . . .2–2 2–4. INPUT DRIVE. . . .2–2 2–5. TRANSMISSION HOUSING. . . .2–2 2–6. TORQUE CONVERTER a. Description . . . .2–2 b. Operation . . . .2–2 2–7. LOCKUP CLUTCH a. Description . . . .2–2 b. Operation . . . .2–3 2–8. OIL PUMP ASSEMBLY

a. Description . . . .2–3 b. Operation . . . .2–3 2–9. OIL PUMP AND FRONT SUPPORT

ASSEMBLY. . . .2–3 2–10. FORWARD CLUTCH AND TURBINE SHAFT a. Description . . . .2–3 b. Operation . . . .2–3

2–11. FOURTH CLUTCH

a. Description . . . 2–4 b. Operation . . . 2–4 2–12. THIRD CLUTCH, CENTER SUPPORT, AND

SECOND CLUTCH

a. Description . . . 2–4 b. Operation of Third Clutch . . . 2–4 c. Operation of Second Clutch . . . 2–5 2–13. FIRST CLUTCH

a. Description . . . 2–5 b. Operation . . . 2–5 2–14. PLANETARY GEAR UNIT

a. Description . . . 2–5 b. Operation . . . 2–6 2–15. LOW CLUTCH (MT 650, 653 Only)

a. Description . . . 2–6 b. Operation . . . 2–6 2–16. LOW PLANETARY GEARING

(MT 650, 653 Only) a. Description . . . 2–7 b. Operation . . . 2–7 2–17. GOVERNOR DRIVE a. Description (MT 650, 653). . . 2–7 b. Description (MTB 653) . . . 2–7 c. Operation . . . 2–7 2–18. SPEEDOMETER DRIVE/SPEED SENSOR WHEEL a. Description . . . 2–7 b. Operation . . . 2–7 2–19. MODULATOR a. Vacuum Modulator. . . 2–8 b. Mechanical Modulator . . . 2–8 c. Electric Modulator . . . 2–8 2–20. CONTROL VALVE ASSEMBLIES

a. Description . . . 2–8 b. Operation . . . 2–8 2–21. OIL PAN AND FILTER

a. Description . . . 2–8 b. Function . . . 2–8

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MT(B) 640, 643, 650, 653 AUTO MATIC TRANSMISSIONS

2–22. REAR COVER a. Description . . . .2–9 b. Function . . . .2–9 2–23. OUTPUT RETARDER a. Description . . . .2–9 b. Function . . . .2–9 2–24. HYDRAULIC SYSTEM a. System Functions . . . .2–9 b. System Schematics . . . .2–9 c. Filter, Pump Circuit . . . .2–9 d. Main-Pressure Circuit (Red). . . .2–9 e. Converter-In (Yellow), Converter-Out

(Orange), Lubrication (Green)

Circuit . . . .2–10 f. Selector Valve, Forward Regulator

Circuit (Red and Blue) — MT 640, 643. . .2–10 g. Selector Valve, Forward Regulator

Circuit (Red and Blue) — MT 650, 653. . .2–10 h. Governor Circuit (Green and White) . . .2–10 i. Modulator Pressure Circuit (Red and

Green) . . . .2–11 j. Trimmer Regulator Valve (Green and

Yellow) . . . .2–12 k. Trimmer Valves . . . .2–12 l. Lockup Circuit . . . . . . .2–12 m. Priority Valve . . . 2–13 n. 2–1 Inhibitor Valve — MT 650, 653 . . .2–13 o. Clutch Circuits, Hold Regulator

Circuits, Drive Ranges . . . .2–13 p. Automatic Upshifts. . . 2–15 q. Automatic Downshifts . . . .2–1 5 r. Downshift and Reverse Inhibiting . . . . .2–15 2–25. RETARDER HYDRAULIC CIRCUIT

COMPONENTS

a. Circuit Schematic . . . 2–15 b. Priority Valve . . . 2–15 c. Driver Retarder Control . . . .2–16 d. Retarder Valve . . . .2–16 e. Cutoff Valve . . . .2–16 f. Retarder Pressure Regulator Valve . . . .2–16 g. Charging Valve. . . .2–16 2–26. RETARDER HYDRAULIC CIRCUIT

FUNCTION

a. Retarder Valve Off (Vehicle Moving) . . .2–16 b. Retarder Valve Partially Applied . . . .2–16 c. Retarder Valve Fully Applied . . . .2–17

2–27. TORQUE PATHS THROUGH THE TRANSMISSION

a. Converter Operation . . . 2–17 b. Lockup Operation . . . 2–17 c. Neutral Operation (MT 640, 643) . . . . 2–18 d. First Range Operation

(MT 640, 643) . . . 2–19 e. Second Range Operation

(MT 640, 643) . . . 2–20 f. Third Range Operation

(MT 640, 643) . . . 2–21 g. Fourth Range Operation

(MT 640, 643) . . . 2–22 h. Reverse Range Operation

(MT 640, 643) . . . 2–23 i. Neutral Operation (MT 650, 653) . . . . 2–24 j. First Range Operation

(MT 650, 653) . . . 2–25 k. Second Range Operation

(MT 650, 653) . . . 2–26 l. Third Range Operation

(MT 650, 653) . . . 2–27 m. Fourth Range Operation

(MT 650, 653) . . . 2–28 n. Fifth Range Operation

(MT 650, 653) . . . 2–29 o. Reverse Range Operation

(MT 650, 653) . . . 2–30

Section 3. PREVENTIVE MAINTENANCE 3–1. SCOPE . . . 3–1 3–2. INSPECTION AND CARE . . . 3–1 3–3. IMPORTANCE OF PROPER

TRANSMISSION FLUID LEVEL

a. Effects of Improper Fluid Level. . . 3–1 b. Foaming and Aerating . . . 3–1 3–4. DIPSTICK MARKINGS . . . 3–1 3–5. TRANSMISSION FLUID LEVEL CHECK

PROCEDURE

a. Preparation . . . 3–2 b. Cold Check . . . 3–2 c. Hot Check . . . 3–3 3–6. KEEPING TRANSMISSION FLUID

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Paragraph Page

MT(B) 640, 643, 650, 653 AUTO MATIC TRANSMISSIONS

3–7. TRANSMISSION FLUID RECOMMENDATIONS

a. Recommended Automatic Transmission Fluid and Viscosity Grade . . . .3–4 3–8. TRANSMISSION FLUID AND FILTER

CHANGE INTERVALS . . . .3–4 3–9. TRANSMISSION FLUID CONTAMINATION a. Examine at Fluid Change . . . .3 –5 b. Metal Particles . . . .3–5 c. Coolant Leakage . . . .3–5 d. Auxiliary Filter . . . .3–6 3–10. TRANSMISSION FLUID AND FILTER

CHANGE PROCEDURES a. Fluid Change Procedure (Standard

Configuration, 4.3 and 5.1 Inch Pan) . . . .3–6 b. Fluid Change Procedure (External

Access Heavy-Duty Configuration, 7.14 Inch Pan). . . .3–8 c. Governor Filter Change Procedures . . . . .3–8 3–11. BREATHER. . . .3–10 3–12. LINKAGE

a. Shift Selector Lever and Control

Linkage. . . .3–10 b. Mechanical Actuator Adjustment. . . .3–11 c. Other Linkage Adjustments . . . .3– 11 3–13. ADJUSTMENT OF SHIFT POINTS

a. Calibrated on Test Stand or in Vehicle . . .3–11 b. Location of Adjusting Components . . . .3–11 c. Checks Before Adjusting Shift Points. . . . .3–11 d. Calibration by Road Test Method . . . . .3–12 e. Calibration by Speedometer Readings

Method . . . .3–12 f. Calibration by Test Stand Method . . . . .3–12 3–14. OIL COOLER . . . . . .3–26 3–15. TRANSMISSION STALL TEST

a. Purpose . . . .3–26 b.Stall Test Preparation . . . .3–27 c. Stall Test Procedures — Vehicles

Without Smoke-Controlled Engines . . .3–27

d. Stall Test Procedures — Vehicles

With Smoke-Controlled Engines . . . 3–27 e. Neutral Cool-Down Check Procedure. . . 3–28 f. Results. . . 3–28 3–16. PRESERVATION AND STORAGE

a. Storage, New Transmissions . . . 3–28 b. Preservation Methods . . . 3–28 c. Storage, One Year — Without

Transmission Fluid . . . 3–28 d. Storage, One Year — With

Transmission Fluid . . . 3–28 e. Restoring Transmission to Service. . . . 3–29 3–17. REPLACEMENT OF COMPONENTS WHILE

TRANSMISSION IS IN THE VEHICLE CHASSIS

a. Replacement of Selector Shaft Seal . . . 3–29 b. Removal of Output Flange . . . 3–30 c. Removal of Dust Shield and Output

Shaft Seal . . . 3–30 d. Removal of Output Shaft Bearing . . . . 3–30 e. Removal of Governor and Speedometer

Drive Gear . . . 3–31 f. Install Governor and Speedometer Drive

Gears, Rear Bearing, Oil Seal, and Dust Shield . . . 3–31 g. Installation of Output

Flange — MT 640, 643 . . . 3–31 h. Installation of Output Flange —

MTB 643, MT(B) 650, 653 . . . 3–33 3–18. TROUBLESHOOTING — BEFORE

REMOVAL OR OPERATION OF

TRANSMISSION . . . 3–33 3–19. TROUBLESHOOTING — BEFORE

REMOVAL AND DURING OPERATION a. Determine Cause of Trouble . . . 3–33 b. Proper Engine Tuning. . . 3–33 3–20. OUTPUT RETARDER

TROUBLE-SHOOTING — BEFORE REMOVAL a. High Speed Mode Pressure Function

Test . . . 3–33 b. Static Mode Pressure Function Test. . . 3–34 3–21. TROUBLESHOOTING — TRANSMISSION

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MT(B) 640, 643, 650, 653 AUTO MATIC TRANSMISSIONS

3–22. TROUBLESHOOTING PROCEDURES a. Troubleshooting Information . . . .3–34 b. Fluid Pressures . . . .3–34 c. Increasing Pump Volume . . . .3–34

Section 4. GENERAL OVERHAUL INFORMATION

4–1. SCOPE . . . .4–1 4–2. TOOLS AND EQUIPMENT

a. Improvised Tools and Equipment . . . .4–1 b. Special Tools . . . .4–1 c. Mechanic’s Tools, Shop Equipment . . . .4–1 4–3. REPLACEMENT PARTS

a. Ordering Information . . . .4–2 c. Parts Normally Replaced . . . .4–2 4–4. CAREFUL HANDLING . . . .4–2 4–5. CLEANING AND INSPECTION

a. Dirt-Free Assembly . . . 4–12 b. Cleaning Parts. . . .4–12 c. Cleaning Bearings. . . .4–12 d. Inspecting Bearings . . . .4–12 e. Keeping Bearings Clean . . . .4–12 f. Inspecting Cast Parts, Machined

Surfaces. . . .4–12 g. Inspecting Bushings, Thrust Washers . . . .4–13 h. Inspecting Oil Seals, Gaskets . . . .4–13 i. Inspecting Gears . . . .4–13 j. Inspecting Shafts. . . .4–14

k. Inspecting Splined Parts . . . .4–14 l. Inspecting Threaded Parts . . . .4–14 m. Inspecting Snaprings . . . .4 –15 n. Inspecting Springs . . . .4–15 o. Inspecting Clutch Plates . . . .4–15 p. Inspecting Swaged, Interference-Fit

Parts . . . .4–15 q. Inspecting Balls in Clutch Housings . . . .4–15 r. Inspecting Seal Contact Surfaces . . . .4–1 5 4–6. ASSEMBLY PROCEDURES

a. Clutches, Pistons. . . .4–15 b. Parts Lubrication. . . 4–15

c. External Pipe Plugs, Hydraulic

Fittings . . . 4–15 d. Oil-Soluble Grease . . . 4–16 e. Lip-Type Seals . . . 4–16 f. Butt-Joint Sealrings . . . 4–16 g. Interference-Fit Parts . . . 4–17 h. Sleeve-Type Bearings and Bushings . . 4–17 i. Bearings (Ball or Roller) . . . 4–17 j. Clutch Snaprings. . . 4–17 4–7. REMOVING (OR INSTALLING)_TRANSMISSION

a. Drain Transmission Fluid . . . 4–17 b. Check Linkages and Lines . . . 4–17 c. Retain Torque Converter . . . 4–17 d. Clean Transmission . . . 4–17 e. Transmission Installation . . . 4–18 4–8. WEAR LIMITS . . . 4–18 4–9. SPRING SPECIFICATIONS. . . 4–18 4–10. TORQUE SPECIFICATIONS. . . 4–18 4–11. SELECTIVE PARTS. . . 4–18 Section 5. DISASSEMBLY OF TRANSMISSION 5–1. SCOPE . . . 5–1 5–2. GENERAL INFORMATION . . . 5–1 5–3. MOUNTING TRANSMISSION IN HOLDING FIXTURE OR OVERHAUL STAND. . . 5–1 a. Mounting of Transmission in

Table-Mounted Holding Fixture. . . 5–1 b. Mounting of Transmission in Overhaul

Stand . . . 5–1 5–4. PREPARATION FOR DISASSEMBLY

(MTB Series Only)

a. Relieving Trapped Hydraulic Pressure. . 5–1 b. Removing Hose Assemblies, Fittings,

and Brackets . . . 5–2 5–5. REMOVAL OF TORQUE CONVERTER, OIL

PAN, AND FILTER

a. Removal of Torque Converter . . . 5–2 b. Removal of Oil Pan and Filter (Standard

Configuration). . . 5–2 c. Removal of Oil Pan and Filter

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Paragraph Page

MT(B) 640, 643, 650, 653 AUTO MATIC TRANSMISSIONS

5–6. REMOVAL OF HYDRAULIC COMPONENTS (MT(B) 640, 643)

a. Modulated Lockup Valve Body . . . .5–3 b. Tube Adapter . . . .5–4 c. Control Valve Assembly . . . .5–4 5–7. REMOVAL OF HYDRAULIC CONTROL

COMPONENTS (MT(B) 650, 653)

a. Modulated Lockup Valve Body . . . .5–4 b. Low Shift Valve Assembly . . . .5–4 c. Control Valve Assembly . . . .5–5 5–8. REMOVAL OF OIL PUMP AND FRONT

SUPPORT . . . .5–5 5–9. REMOVAL OF FORWARD, FOURTH, AND

THIRD CLUTCHES, AND CENTER SUPPORT

a. Forward Clutch. . . .5– 6 b. Fourth Clutch . . . .5–6 c. Third Clutch . . . .5–6 d. Center Support . . . .5–6 5–10. REMOVAL OF GOVERNOR, GEAR UNIT,

SECOND CLUTCH, AND FIRST CLUTCH a. Governor . . . .5–7 b. Gear Unit . . . .5–8 c. Second Clutch. . . .5–8 d. First Clutch . . . .5–8 5–11. REMOVAL OF GEAR UNIT, SECOND

CLUTCH, FIRST CLUTCH, AND GOVERNOR (MTB 643, MT(B) 650, 653) a. Gear Unit . . . .5–8 b. Second Clutch. . . .5–8 c. First Clutch . . . .5–9 d. Governor . . . .5–9 5–12. REMOVAL OF REAR COVER (MT 640, 643,

650, 653)

a. Positioning . . . .5–9 b. MT 640, 643 Rear Cover . . . .5–9 c. MT 650, 653 Rear Cover . . . .5–9 5–13. REMOVAL OF OUTPUT RETARDER

(MTB 643, 653)

a. Retarder Control Valve Assembly . . . . .5–10 b. Retarder Housing . . . .5–10 c. Retarder Adapter Housing . . . .5–12

5–14. REMOVAL OF LOW CLUTCH, LOW PLANETARY, AND LOW GEAR ADAPTER HOUSING (MT(B) 650, 653)

a. Low Clutch . . . 5–12 b. Low Planetary Carrier . . . 5–12 c. Low Clutch Adapter Housing. . . 5–12

Section 6. REBUILD OF SUBASSEMBLIES

6–1. SCOPE

a. Section . . . 6–1 b. Procedures. . . 6–1 6–2. GENERAL INFORMATION FOR REBUILD

OF SUBASSEMBLIES . . . 6–1 6–3. TORQUE CONVERTER ASSEMBLY

a. Check the End Play. . . 6–1 b. Disassembly . . . 6–2 c. Rebuilding Stator Assembly. . . 6–4 d. Rebuilding Torque Converter Turbine

Assembly . . . 6–6 e. Rework of Converter Pump Hub . . . 6–8 f. Assembly . . . 6–8 6–4. MODULATED LOCKUP VALVE BODY

ASSEMBLY

a. Disassembly . . . 6–10 b. Assembly . . . 6–10 6–5. LOW SHIFT VALVE ASSEMBLY

(MT(B) 650, 653)

a. Disassembly . . . 6–11 b. Assembly . . . 6–11 6–6. CONTROL VALVE ASSEMBLY

a. Disassembly . . . 6–11 b. Assembly . . . 6–13 6–7. RETARDER CONTROL VALVE ASSEMBLY

(MTB Series Only)

a. Disassembly . . . 6–15 b. Assembly . . . 6–16 6–8. OIL PUMP AND FRONT SUPPORT

ASSEMBLY

a. Disassembly . . . 6–16 b. Rework of Front Support Sealring

Grooves. . . 6–18 c. Assembly . . . 6–18

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MT(B) 640, 643, 650, 653 AUTO MATIC TRANSMISSIONS

6–9. FORWARD CLUTCH AND TURBINE SHAFT a. Disassembly . . . .6–23 b. Rework of Rotating Sealring Bore,

Forward Clutch. . . .6–24 c. Assembly . . . .6–26 6–10. FOURTH CLUTCH

a. Disassembly . . . .6–28 b. Assembly . . . .6–28 6–11. CENTER SUPPORT ASSEMBLY

a. Disassembly . . . .6–30 b. Rework Center Support Anchor Bolt

Hole. . . .6–30 c. Rework of Center Support for One

Piece Thrust Bearing Race Assembly. . .6–31 d. Rework of Non-Eccentric Center

Support to Eccentric Support . . . 6-31 e. Assembly . . . .6–32 6–12. GEAR UNIT AND MAIN SHAFT ASSEMBLY

(MT(B) 650, 653)

a. Disassembly . . . .6–34 b. Installing Replacement Sun Gear Shaft

Bushings . . . .6–36 c. Assembly . . . .6–36 6–13. GEAR UNIT AND MAIN SHAFT ASSEMBLY

(MT 640, 643)

a. Disassembly . . . .6–39 b. Assembly . . . .6–39 6–14. GEAR UNIT AND MAIN SHAFT ASSEMBLY

(MTB 643) a. Disassembly . . . .6–41 b. Assembly . . . .6–42 6–15. OUTPUT SHAFT (MT 650, 653) a. Disassembly . . . .6–42 b. Assembly . . . .6–43 6–16. REAR COVER ASSEMBLY (MT 650, 653)

a. Disassembly . . . .6–43 b. Assembly . . . .6–45 6–17. REAR COVER ASSEMBLY (MT 640, 643)

a. Disassembly . . . .6–47 b. Assembly . . . .6–47

6–18. OUTPUT RETARDER HOUSING (MTB 643, 653)

a. Disassembly . . . 6–48 b. Assembly . . . 6–49 6–19. RETARDER ADAPTER HOUSING

(MTB 643, 653)

a. Disassembly . . . 6–52 b. Assembly . . . 6–55 6–20. LOW CLUTCH ADAPTER HOUSING AND

FIRST CLUTCH PISTON (MT(B) 650, 653) a. Disassembly . . . 6–56 b. Assembly . . . 6–57 6–21. TRANSMISSION HOUSING a. Disassembly . . . 6–57 b. Assembly . . . 6–58 6–22. GOVERNOR a. Disassembly . . . 6–59 b. Assembly . . . 6–59 6–23. CLUTCH STACK MEASUREMENT

a. Methods . . . 6–59 b. Forward Clutch . . . 6–60 c. Fourth Clutch . . . 6–60 d. Low Clutch — MT 650, 653 . . . 6–60 e. First Clutch . . . 6–60 f. Second and Third Clutches. . . 6–61 6–24. PLANETARY CARRIER ASSEMBLIES

a. Assembly Inspection. . . 6–61 b. Removal of Pinion Components. . . 6–62 c. Replacing Bushing in Front and Low

Planetary Carrier Assemblies . . . 6–62 d. Rework Center Carrier for Non-Rotating

Thrust Washers . . . 6–65 e. Installation of Pinion Components. . . . 6–65

Section 7. ASSEMBLY OF TRANSMISSION 7–1. SCOPE . . . 7–1 7–2. GENERAL INFORMATION FOR

FINAL ASSEMBLY . . . 7–1 7–3. INSTALLATION OF CLUTCHES, CENTER

SUPPORT, PLANETARY GEARING, AND REAR COVER OR RETARDER

a. Selecting Center Support Snapring . . . . 7–1 b. Second Clutch Clearance . . . 7–2

(11)

Paragraph Page

MT(B) 640, 643, 650, 653 AUTO MATIC TRANSMISSIONS

c. Rear Cover — MT 640, 643. . . .7–3 d. Output Retarder — MTB 643 . . . .7 –3 e. First Clutch Clearance — MT(B) 640,

643 . . . .7–5 f. Low Clutch Clearance —

MT(B) 650, 653 . . . .7–6 g. Low Clutch Planetary — MT(B) 650,

653 . . . .7–6 h. Rear Cover, Governor —

MT 650, 653 . . . .7–8 i. Output Retarder — MTB 653 . . . .7–9 j. First Clutch Clearance —

MT(B) 650, 653 . . . .7–10 k. Gear Unit Assembly —

MT(B) 640, 643 . . . .7–11 l. Gear Unit Assembly —

MT(B) 650, 653 . . . .7–12 m. Second Clutch. . . . . . .7–12 n. Center Support . . . .7–12 o. Third Clutch Clearance. . . .7–13 p. Fourth Clutch . . . .7–14 q. Forward Clutch and Turbine Shaft. . . . .7–14 7–4. INSTALLATION OF OIL PUMP AND

FRONT SUPPORT . . . .7–15 7–5. INSTALLATION OF HYDRAULIC

CONTROL COMPONENTS a. Control Valve Assembly —

MT(B) 640, 643 . . . .7–16 b. Tube Adapter — MT(B) 640, 643 . . . . .7–17 c. Control Valve Assembly —

MT(B) 650, 653 . . . .7–17 d. Low Shift Valve Body —

MT(B) 650, 653 . . . .7–18 e. Valve Tubing — MT(B) 650, 653 . . . . .7–19 f. Modulated Lockup Valve Assembly . . .7–19 7–6. INSTALLATION OF OIL FILTER, PAN,

TORQUE CONVERTER

a. Oil Filter (Standard Configuration) . . . .7–20 b. Oil Pan . . . .7–20 c. Oil Filter Canister (Heavy-Duty

Configuration) . . . .7–21 d. Oil Pan and Filter (Heavy-Duty

Configuration) . . . .7–21 e. Torque Converter . . . .7–21

7–7. INSTALLING RETARDER EXTERNAL COMPONENTS (MTB 643, 653)

a. Retarder Valve Body . . . 7–22 b. Hose Assemblies, Fittings, and

Brackets . . . 7–22 7–8. INSTALLING GOVERNOR AND

GOVERNOR COVER. . . 7–23 7–9. INSTALLATION OF OUTPUT

COMPONENTS (MT 640, 643, 650, 653) a. Governor and Speedometer Drive

Gears, Ring Bearing . . . 7–24 b. Oil Seal, Dust Shield . . . 7–25 7–10. REMOVAL OF TRANSMISSION FROM

OVERHAUL STAND AND INSTALLATION OF NEUTRAL START SWITCH

a. Supporting Transmission . . . 7–26 b. Installing PTO Cover . . . 7–26 7–11. CHECKING SHIFT POINTS . . . 7–27 7–12. POWER TAKEOFF COMPONENTS

a. Establishing PTO Backlash . . . 7–27 b. New Installation . . . 7–27

Section 8. WEAR LIMITS AND SPRING DATA 8–1. WEAR LIMITS DATA

a. Maximum Variations . . . 8–1 b. Cleaning and Inspection . . . 8–1 8–2. SPRING DATA . . . 8–1

Section 9. CUSTOMER SERVICE

9–1. OWNER ASSISTANCE . . . 9–1 9–2. SERVICE LITERATURE . . . 9–2

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MT(B) 640, 643, 650, 653 AUTO MATIC TRANSMISSIONS

LIST OF FOLDOUT ILLUSTRATIONS

(Back of Service Manual)

CROSS–SECTION VIEWS

Foldout

1 Model MT(B) 640, 643 Automatic Transmission 2 Model MT(B) 650, 653 Automatic Transmission SCHEMATIC VIEWS

Foldout

3 Model MT(B) 640, 643 Transmission Hydraulic System 4 Model MT(B) 650, 653 Transmission Hydraulic System 5 Model MTB 643, 653 Output Retarder Hydraulic System EXPLODED VIEWS

Foldout

6 Torque Converter and Lockup Clutch 7,A Oil Pump and Front Support Assembly 7,B Forward Clutch and Turbine Shaft Assembly 8,A Fourth Clutch Assembly

8,B Third Clutch, Center Support, and Second Clutch 9,A Gear Unit Assembly — MT(B) 640, 643 9,B Gear Unit Assembly — MT(B) 650, 653

10,A Transmission Housing, Standard Oil Filter and Oil Pan Conﬁgurations 10,B Heavy-Duty Oil Filter and Oil Pan Conﬁguration

11,A First Clutch and Rear Planetary Ring Gears

11,B Low Clutch, Planetary, and Adapter Housing — MT(B) 650, 653 12,A Rear Cover Components — MT 640, 643

12,B Output Shaft and Rear Cover Components — MT 650, 653 13 Control Valve Body Assembly — MT(B) 640, 643 14 Control Valve Body Assembly — MT(B) 650, 653 15,A Modulated Lockup Valve Body Assembly

15,B Low Shift Valve Body Assembly — MT(B) 650, 653 16 Parking Brake Assemblies

17,A Retarder Accumulators and Go vernor 17,B Retarder Control Valve

18,A Retarder Housing 18,B Retarder Clutch

19,A MTB 643 Retarder Adapter 19,B MTB 653 Retarder Adapter

(13)

Section 1 — GENERAL INFORMA TION

1–1.

SCOPE OF MANUAL

a

a.. CCoovveerragagee

1. This Service Manual describes the operation, maintenance, and overhaul procedures for the MT 640, MT(B) 643, MT 650, and MT(B) 653 Series automatic transmissions (Figures 1–1 through 1–8). Descriptions of the major com-ponents of the transmissions, the function and operation of the hydraulic system, wear limits, and inspection procedures are included. Torque speciﬁcations are given with each assembly step and on the exploded view foldouts at the back of this manual.

2. Because of similarities between models, in-structions apply generally to all models. Where procedures vary between models, instructions identify speciﬁc models.

b

b.. IlIlluluststratratioionsns..Overhaul procedures are illustrated mainly by photographs. Line drawings are used to sup-plement detailed assembly procedures; cross sections show torque paths and the relationship of assembled parts. Cross sections, color-coded hydraulic schemat-ics, and exploded views are on foldouts at the back of the manual. The foldouts may be opened for reference while studying the text.

c.

c. MaiMaintentenannance ce InfInformormatiation.on.Each task outlined in this Service Manual has been successfully accom-plished by service organizations and individuals. It is not expected that every service organization or indi-vidual will possess the required special tooling, train-ing, or experience to perform all the tasks outlined. However, any task outlined herein may be performed if the following conditions are met:

1. The organization or individual has the required knowledge of the task through:

•• Formal instruction in an Allison or Distributor training facility.

•• On-the-job instruction by an Allison or Distributor representative.

•• Experience in performing the task. 2. The work environment is suitable to prevent

contamination or damage to transmission parts or assemblies.

3. Required tools and ﬁxtures are available as outlined in the Service Manual.

4. Reasonable and prudent maintenance prac-tices are utilized.

NOTE: NOTE:

Service organizations and individuals are Service organizations and individuals are encour-aged to contact

aged to contact their local Allison Transmission Dis-their local Allison Transmission Dis-tributor for information and guidance on any of the tributor for information and guidance on any of the tasks outlined herein.

tasks outlined herein.

1–2. SUPPLEMENTARY INFORMATION

Supplementary information will be issued, as required, to cover any improvements made after publication of this manual. Check with your dealer or distributor to ensure you have the latest information.

1–3. ORDERING PARTS

a.

a. TTranransmismissission Nameon Nameplaplate.te.The nameplate (Fig-ure 1–9) is located on the right-rear side of the trans-mission. The nameplate shows the transmission serial number, part number (assembly number), and model designation, all three of which must be supplied when ordering replacement parts or requesting service infor-mation.

b.

b. ParParts Cts Catalatalog. Dog. Do not o not ordeorderr by illustration item numbers on exploded views in this manual. All re-placement parts should be ordered from your distribu-tor or dealer. Parts are listed in the current Parts Cata-log PC1316EN.

1–4. GENERAL DESCRIPTION

a.

a. NuNumbmber oer of Spf Speeeedsds..The MT(B) 640, 643 have four forward speeds and one reverse. The MT(B) 650, 653 have ﬁve forward speeds and one reverse. Shifting within the forward ranges selected by the operator is fully automatic.

b.

b. TTorque orque ConConverter verter and Lockand Lockup Cluup Clutch.tch. An Allison three-element torque converter (Foldout 1 or 2) transmits power from the engine to the transmission gearing. The torque converter serves as both a ﬂuid coupling and a torque multiplier. MT 600 Series transmissions also include a lockup clutch in the torque converter assembly.

(14)

MT(B) 640, 643, 650, 65 3 AUTO MATIC TRANSMISSIONS

Figure 1–1.

Figure 1–1. Model MT 640 or MT 643 AModel MT 640 or MT 643 Automatic utomatic TrTransmission — Left-Rear ansmission — Left-Rear ViewView

Figure 1–2.

Figure 1–2. Model MT 640 or MT 643 Automatic Model MT 640 or MT 643 Automatic TTransmission — Right-Front ransmission — Right-Front ViewView TRANSMISSION TRANSMISSION HOUSING HOUSING MOUNTING PAD MOUNTING PAD SPEEDOMETER SPEEDOMETER DRIVE OPENING DRIVE OPENING GOVERNOR PRESSURE GOVERNOR PRESSURE BREATHER BREATHER REAR COVER REAR COVER PARKING BRAKE PARKING BRAKE MOUNTING PAD MOUNTING PAD OUTPUT SHAFT OUTPUT SHAFT GOVERNOR COVER GOVERNOR COVER GOVERNOR FILTER GOVERNOR FILTER OIL PAN OIL PAN MODULATOR MODULATOR ACTUATOR OPENING ACTUATOR OPENING NEUTRAL START NEUTRAL START SWITCH PLUG SWITCH PLUG MAIN PRESSURE MAIN PRESSURE SELECTOR SHAFT SELECTOR SHAFT

FILL TUBE OPENING FILL TUBE OPENING

H00042.01 PTO COVER PTO COVER TO COOLER PORT TO COOLER PORT TORQUE TORQUE CONVERTER CONVERTER NAMEPLATE NAMEPLATE FROM FROM COOLER COOLER PORT PORT DRAIN PLUG DRAIN PLUG

FILL TUBE OPENING

FILL TUBE OPENING OIL PANOIL PAN

CONVERTER CONVERTER RESTRAINING RESTRAINING STRAP STRAP H00041

(15)

GENERAL INFORMATION

Figure 1–3.

Figure 1–3. Model MT 650 or MT 653 AModel MT 650 or MT 653 Automatic utomatic TTransmission — Left-Rear ransmission — Left-Rear ViewView

Figure 1–4.

Figure 1–4. Model MT 650 or MT 653 Automatic Model MT 650 or MT 653 Automatic TrTransmission — Right-Front ansmission — Right-Front ViewView FLANGE NUT FLANGE NUT ADAPTER HOUSING ADAPTER HOUSING PARKING BRAKE PARKING BRAKE MOUNTING PAD MOUNTING PAD SELECTOR SHAFT SELECTOR SHAFT REAR COVER REAR COVER SPEEDOMETER SPEEDOMETER DRIVE OPENING DRIVE OPENING GOVERNOR FILTER GOVERNOR FILTER GOVERNOR COVER GOVERNOR COVER MODULATOR MODULATOR ACTUATOR ACTUATOR OPENING OPENING NEUTRAL START NEUTRAL START SWITCH PLUG SWITCH PLUG MAIN PRESSURE MAIN PRESSURE

FILL TUBE OPENING FILL TUBE OPENING TRANSMISSION HOUSING TRANSMISSION HOUSING BREATHER BREATHER GOVERNOR PRESSURE GOVERNOR PRESSURE H00001.01 BRAKE MOUNTING BRAKE MOUNTING PAD PAD NAMEPLATE NAMEPLATE OIL PAN OIL PAN PTO COVER PTO COVER MOUNTING PAD MOUNTING PAD TO COOLER TO COOLER FROM COOLER FROM COOLER DRAIN PLUG DRAIN PLUG

FILL TUBE OPENING FILL TUBE OPENING

TORQUE TORQUE CONVERTER CONVERTER

(16)

MT(B) 640, 643, 650, 65 3 AUTO MATIC TRANSMISSIONS

Figure 1–5.

Figure 1–5. Model MTB 643 AutoModel MTB 643 Automatic matic TTransmission — Right-Rear ransmission — Right-Rear ViewView

Figure 1–6.

Figure 1–6. Model MTB 643 AuModel MTB 643 Automatic tomatic TTransmission — Left-Rear ransmission — Left-Rear ViewView TO RETARDER TO RETARDER CLUTCH CLUTCH FROM EXTERNAL FROM EXTERNAL FILTER TO LUBE FILTER TO LUBE RETARDER HOUSING RETARDER HOUSING ADAPTER HOUSING

ADAPTER HOUSING FROM CONVERTERFROM CONVERTER

ACCUMULATOR ACCUMULATOR

CHECK VALVE CHECK VALVE

RETARDER VALVE BODY RETARDER VALVE BODY REGULATING VALVE ASSEMBLY REGULATING VALVE ASSEMBLY

TO EXTERNAL FILTER TO EXTERNAL FILTER

H00003

OUTPUT FLANGE NUT OUTPUT FLANGE NUT

FILL TUBE FILL TUBE OPENING OPENING TO RETARDER CLUTCH TO RETARDER CLUTCH OUTPUT FLANGE OUTPUT FLANGE GOVERNOR COVER GOVERNOR COVER BREATHER

BREATHER SPEEDOMETER PORTSPEEDOMETER PORT

(17)

GENERAL INFORMATION

Figure 1–7.

Figure 1–7. Model MTB 653 Automatic Model MTB 653 Automatic TTransmission — Right-Front ransmission — Right-Front ViewView

Figure 1–8.

Figure 1–8. Model MTB 653 AutoModel MTB 653 Automatic matic TraTransmission — Right-Rear nsmission — Right-Rear ViewView FROM COOLER FROM COOLER PORT PORT TO COOLER TO COOLER PORT PORT FROM EXTERNAL FROM EXTERNAL FILTER TO LUBE FILTER TO LUBE RETARDER CONTROL RETARDER CONTROL AIR PRESSURE AIR PRESSURE CHECK CHECK VALVE VALVE TO EXTERNAL TO EXTERNAL FILTER FILTER MOUNTING MOUNTING PADS PADS CONVERTER CONVERTER RESTRAINING RESTRAINING STRAP STRAP H00136.1 REAR SUPPORT REAR SUPPORT MOUNTING PAD MOUNTING PAD ACCUMULATOR

ACCUMULATOR RETARDER VALVE BODYRETARDER VALVE BODY FROM CONVERTER FROM CONVERTER ADAPTER HOUSING ADAPTER HOUSING TO RETARDER CLUTCH TO RETARDER CLUTCH RETARDER HOUSING RETARDER HOUSING REGULATING REGULATING VALVE ASSEMBLY VALVE ASSEMBLY TO EXTERNAL FILTER TO EXTERNAL FILTER

FROM EXTERNAL FILTER FROM EXTERNAL FILTER TO LUBE

TO LUBE

(18)

MT(B) 640, 643, 650, 653 AUTO MATIC TRANSMISSIONS

Figu

Figure 1–9.re 1–9. TTransmransmissiission Nameplaon Namepla tete

c.

c. PlaPlanetanetary ry GearGearinging, C, Clutclutcheshes..The MT(B) 640, 643 have three planetary gear sets that produce four for-ward speeds and one reverse speed. The planetaries are controlled by ﬁve hydraulically-actuated clutches. The MT(B) 650, 653 have four planetary gear sets that pro-duce ﬁve forward speeds and one reverse speed. The planetaries are controlled by six hydraulically-actuated clutches. All gearing is in constant mesh.

E C A P S O R E A E L I B O M O T U A D E T T I I N U U A A C I R E M A F O S R E K R O W W T N E M E L P M I L A A R R U T T LL UU C C I R R G A A D N A UAW UAW 933 933 DIVISION OF DIVISION OF GENERAL MOTORS GENERAL MOTORS CORPORATION CORPORATION INDIANAPOLIS INDIANAPOLIS INDIANA INDIANA SERIAL NO. SERIAL NO. XXXXX XX XXXXX XXXXXXX MODEL MODEL NO. NO. PART NO. PART NO. V01251 d.

d. OutOutput put RetRetardearderr..The MT 600 Series retarder provides power absorption to slow vehicle forward motion. It is located at the rear of the transmission as an integral part of the transmission (Foldout 1 or 2). The overall transmission length, from the ﬂywheel housing mounting face to the output ﬂange face, re-mains essentially the same with the addition of the output retarder.

1–5. OPERATING INSTRUCTIONS

Refer to Operator’s Manual OM1334EN for operating instructions.

1–6. SPECIFICATIONS AND DATA

The speciﬁcations and data shown in Table 1–1 are ap-plicable to MT(B) 640, 643, 650, and 653 transmis-sions.

T

Table able 1–1.1–1. SpeciﬁSpeciﬁcations cations and Dand Dataata

INPUT RATINGS — MT(B) 643/653 INPUT RATINGS — MT(B) 643/653

Value

Parameter General Truck Transit & Airport

Shuttle Bus

Emergency Equipment

School Bus & Motorhome

Agricultural_{Hauler &}

Spreader Unit Input Speed

Maximum full load governed speed

— MT 643, 653 4000 4000 4000 4000 4000 rpm

Maximum full load governed speed —

MTB 643 3000 3000 3000 3000 3000 rpm

Minimum full load governed speed 2200 2200 2200 2200 2200 rpm

Minimum idle speed in drive 500 500 500 500 500 rpm

Input Power Maximum net 250 (186) 210 (156) 250 (186) 250 (186) 250 (186) hp (kW) Input Torque Maximum net 640 (868) 590 (800) 640 (868) 640 (868) 640 (868) lb ft (N·m) Turbine Torque Maximum net 1210 (1640) 1210 (1640) 1210 (1640) 1210 (1640) 1210 (1640) lb ft (N·m)

Gross vehicle weight (GVW) 73280 (33240) 42000 (19051) 55000 (24948) 42000 (19051) 55000 (24948) lb (kg)

(19)

GENERAL INFORMATION

T

Table able 1–1.1–1. SpeciSpeciﬁcationﬁcations ans and Datd Dataa(cont’d) Mounting:

Transmission to engine . . . SAE 2 automotive ﬂywheel housing Transmission to vehicle. . . Two side mounting pads on input housing

(optional use)

Retarder to vehicle. . . Two top mounting pads or two rear mount-ing pads

Drive . . . . . . . . . . . . . Flexplate Rotation (viewed from input):

Input. . . Clockwise Output (in forward ranges) . . . Clockwise Torque converter:

Type. . . Single-stage, 3-element, multiphase Stall torque ratio . . . TC 350-3.04:1; TC 360-2.86:1; TC

370-2.40:1; TC 378-2.27:1; TC 380-1.82:1 Lockup clutch . . . Automatic in selected ranges Drive range and sequences:

MT 640, 643 . . . Reverse, neutral 1–2–3–4, 1–2–3, 1–2, 1 MT 650, 653 (Third range hold option) . . . Reverse, neutral 2–3–4–5, 2–3–4, 2–3, 1 MT 650, 653 (Second range hold option) . . . Reverse, neutral 2–3–4–5, 2–3–4, 2, 1 Drive range and shift control . . . Mechanical (external)

Shifting. . . Hydraulic valve body (internal control) Shift modulation:

Diesel models . . . Air, mechanical, or electric Gasoline models . . . Vacuum or mechanical

Clutches . . . Fluid-cooled, hydraulically-actuated, spring-released, self-compensating for wear Gearing. . . Planetary, straight-cut spur, constant mesh Hydraulic System:

Fluid capacity (excluding external circuits) . . . . Initial Fill Initial Fill After Rebuild After Rebuild Reﬁll After Reﬁll After Servicing Servicing U.S. Qts Liters U.S. Qts Liters MT 640, 643 — 4.34 inch (110.2 mm) pan . . . 21 20 12 11

MT 650, 653 — 5.10 inch (129.5 mm) pan . . . 21 20 15 14 MTB 643 — 4.34 inch (110.2 mm) pan . . . 22 21 12 11 MTB 653 — 5.10 inch (129.5 mm) pan . . . 22 21 15 14

Fluid filter . . . Integral full-flow replaceable paper element filter or permanent sump screen

Cooling circuit filter . . . Customer supplied full-flow filter with bypass

Pump . . . . . . . . . . . . . Engine driven, positive displacement Fluid type . . . DEXRON®_{-III and Allison-approved C-4}

(20)

MT(B) 640, 643, 650, 65 3 AUTO MATIC TRANSMISSIONS

Temperatures*:

Sump (max intermittent) . . . 250˚F (121˚C) Sump (min continuous) . . . 100˚F ( 38˚C) Converter-out (max intermittent). . . 300˚F (149˚C) Retarder operation . . . 330˚F (165˚C) Normal operation (sump). . . 160–200˚F (71–93˚C) Normal operation (converter-out) . . . 180–220˚F (82–104˚C) Fluid pressures:

Forward drive range (vehicle brakes applied) En Engigine ne rrpmpm MT MT 646400 (prior to S/N 47020) (prior to S/N 47020) MT 640, 643 MT 640, 643 (eff. with S/N 47020) (eff. with S/N 47020) MT 650 MT 650 (prior to S/N 47285) (prior to S/N 47285) MT 650, 653 MT 650, 653 (eff. with S/N 47285) (eff. with S/N 47285) 600 125 psi min. (861 kPa) 125 psi min. (861 kPa) 125 psi min. (861 kPa) 125 psi min. (861 kPa) 1200 137–167 psi (945–1151 kPa) 158–200 psi (1089–1378 kPa) 187–217 psi (1289–1496 kPa) 158–200 psi (1089–1378 kPa)

Reverse drive range (vehicle brakes applied, driveline disconnected)

E

Ennggiinne e rrppmm MMaaiin n PPrreessssuurree RReevveerrsse e PPrreessssuurree LLuubbe e PPrreessssuurree

2000 275–326 psi (1895–2245 kPa) 275–326 psi (1895–2245 kPa) 15 psi min. (103 kPa min.) Speedometer drive:

Type . . . Tone wheel or spiral gear

MT 640, 643 drive gear data . . . 5 and 8 tooth lh helix angle or 16-tooth tone wheel MT 650, 653 drive gear data . . . 7, 8, and 11 tooth lh helix angle or 16-tooth tone wheel MTB 643, 653 drive gear data . . . 17 tooth lh helix angle

Driven gear . . . Supplied by customer Power takeoff:

Type . . . Converter driven Mounting flange . . . SAE 6-bolt, one opening

Gear data. . . 6 pitch, 64 teeth, 20 degree pressure angle Location . . . Right side (viewed from rear)

Parking brake provision:

Drum type. . . 12 x 3 or 12 x 4 Weight . . . . . . . . . 50 lb (23 kg) Output retarder models . . . None

Output flange. . . Supplied by customer

T

(21)

GENERAL INFORMATION

Dry weight (less parking brake):

MT 640, 643 . . . 510 lb (231 kg) MT 650, 653 . . . 602 lb (273 kg) MTB 643 . . . 638 lb (289 kg) MTB 653 . . . . . . . . . 730 lb (331 kg)

TRANSMISSION RATIOS (Mechanical**):

MT(B) 640, 643 MT(B) 640, 643

R

Raannggee CClluuttcchh((eess) ) EEnnggaaggeedd RaRattiioo

Neutral First 0

First Forward and first 3.58:1 Second Forward and second 2.09:1 Third Forward and third 1.39:1 Fourth Forward and fourth 1.00:1 Reverse Fourth and first 5.67:1

MT(B) 650, 653 MT(B) 650, 653

R

Raannggee CClluuttcchh((eess) ) EEnnggaaggeedd RaRattiioo

Neutral First 0

First Forward and low 8.05:1 Second Forward and first 3.58:1 Third Forward and second 2.09:1 Fourth Forward and third 1.39:1 Fifth Forward and fourth 1.00:1 Reverse Fourth and first 5.67:1

Table 1–1. Speciﬁcations and Data Table 1–1. Speciﬁcations and Data(cont’d)

** Overall torque multiplication ratio of transmission (output stalled) is the product of the converter torque multiplication ratio (see torque converter) and the mechanical (gear) ratio.

(22)

MT(B) 640, 643, 650, 653 AUTO MATIC TRANSMISSIONS

NOTES

(23)

2–1.

SCOPE

This section describes the transmission components, explains their functions, and details the hydraulic sys-tem and torque paths. Where features are common to all models, no reference is made to models. Where features are speciﬁc to a model, the model is noted.

2–2. DESIGNATION OF CLUTCHES

AND PLANETARY GEAR SETS

a.

a. ClClututch Desch Des igignatnatioionsns (Figure 2–1). The MT 640 and 643 have ﬁve clutches and the MT 650 and 653 have six. The additional MT 650 and 653 clutch is the low clutch. Each clutch in the same physical location has the same name, regardless of model or clutch drive function.

b.

b. PlaPlanetnetary Geaary Gea r Set Desr Set Des ignignatiationsons (Figure 2–1). The MT 640 and 643 have three planetary gear sets, designated as front, center, and rear, while the MT 650 and 653 have four. The additional MT 650 and 653 gear set is the low planetary. Each gear set in the same physical location has the same name, regardless of model or clutch drive function.

2–3. MOUNTING

a.

a. TTo o EnEngiginene.. Transmission housing 16 (Foldout 10,A) is machined to provide an SAE 2 mounting ﬂange. This ﬂange is mated with an SAE 2 bolt circle at the rear of the engine.

b

b.. TTo Vo Vehehiciclele.. Two side-mount pads are provided at the front of the transmission housing. Each pad has four1 ⁄ 2-13 threaded holes. A top-mount pad is pro-vided on the transmission rear cover (MT 640, 643) or adapter housing (MT 650, 653). This pad has two5_⁄8-11 threaded holes.

Section 2 — DESCRIPTION AND OPERATION

Figure

Figure 2–1.2–1. Uniform Uniform Clutch Clutch and Gear and Gear DesignationsDesignations

V00752 LOCKUP LOCKUP CLUTCH CLUTCH FORWARD FORWARD CLUTCH CLUTCH

LOW GEAR SET LOW GEAR SET (FIVE-SPEED MODELS ONLY) (FIVE-SPEED MODELS ONLY)

FRONT FRONT GEAR SET GEAR SET THIRD THIRD CLUTCH CLUTCH SECOND SECOND CLUTCH CLUTCH FIRST FIRST CLUTCH CLUTCH LOW CLUTCH LOW CLUTCH

(FIVE-SPEED MODELS ONLY) (FIVE-SPEED MODELS ONLY)

REAR GEAR SET REAR GEAR SET

CENTER GEAR SET CENTER GEAR SET FOURTH FOURTH CLUTCH CLUTCH F FRROONNTT RREEAARR

(24)

MT(B) 640, 643, 650, 653 AUTO MATIC TRANSMISSIONS

c.

c. OutOutput put ReRetartarder der MouMount.nt. Transmissions with the output retarder require special attention when mount-ing. The additional weight of the retarder makes it nec-essary to overhang the transmission behind the engine using rear support pads. Each rear pad in the retarder housing has two M12 x 1.75-6H threaded holes that are 1.18 inches (30 mm) deep. Each top pad has one M14 x 2-6H threaded hole that is also 1.18 inches (30 mm) deep. The converter housing side-mount pads cannot be used with MTB 653 direct-mount units. Only remote-mount units and MTB 643 direct-remote-mount units may be installed using the side-mount pad on the converter housing with a rear support.

2–4. INPUT DRIVE

A ﬂexplate assembly (supplied by the vehicle manu-facturer) connects the engine to the torque converter pump cover 6 (Foldout 6), which is the input member of the transmission.

2–5. TRANSMISSION HOUSING

Transmission housing 16 (Foldout 10,A) is cast alumi-num. It is machined to receive the clutches, rear cover, adapter housing, front and center supports, control valve, and oil pan. A power takeoff mounting pad is provided on the right side.

2–6. TORQUE CONVERTER

a.

a. DeDescscririptptioionn (Foldout 6). The torque converter consists of three elements: pump assembly 42, stator assembly 24, and turbine assembly 20. These are vaned elements which are cast aluminum. Pump as-sembly 42 is the input member and is driven by the en-gine. Turbine 20 is splined to the forward clutch and turbine shaft assembly 2 (Foldout 7,B). Stator assem-bly 24 (Foldout 6) is the reaction (torque multiplying) element. The stator is supported on freewheel roller race 32, which is splined to valve and front support as-sembly 22 (Foldout 7,A). This stator arrangement pro-vides an over-running clutch which permits the stator to rotate freely in one direction and lockup in the op-posite direction.

b

b.. OpOpereratatioionn(Foldout 6)

1. The torque converter assembly is continually filled with fluid, which provides converter cooling and lubrication. Transmission fluid is

the power transmitting medium in the torque converter. When the engine drives the con-verter, the pump vanes throw ﬂuid against the turbine vanes. The impact of the ﬂuid against the turbine vanes rotates the turbine. 2. The turbine, splined to the turbine shaft,

trans-mits torque to the transmission gearing. At en-gine idle speed, the impact of fluid against the turbine vanes is minimal. At high engine speed the impact of fluid on the turbine is much greater, and high torque is produced. 3. Fluid thrown into the turbine flows to the stator

vanes. The stator vanes change the direction of flow (when the stator is locked against rota-tion), and direct the fluid to the pump in a di-rection that assists the rotation of the pump. The redirection of the fluid by the stator en-ables the torque converter to multiply the input torque.

4. Greatest torque multiplication occurs when the turbine is stalled, and the pump is rotating at its highest speed. Torque multiplication decreases as the turbine speed approaches pump speed. 5. When turbine speed approaches pump speed,

fluid flowing to the stator begins striking the backs of the stator vanes. This rotates the stator in the same direction as the turbine and pump. At this point, torque multiplication stops and the converter becomes, in effect, a fluid cou-pling.

6. The torque converter accomplishes three main functions. It acts as a disconnect clutch be-cause little torque is transmitted at engine idle speed. It multiplies torque at low turbine/high pump speed to give greater starting or driving effort when needed. Finally, it acts as a ﬂuid coupling to efﬁciently transmit engine torque to the transmission gearing during drive, other than idle or starting.

2–7. LOCKUP CLUTCH

a.

a. DeDescscririptptioionn(Foldout 6). The lockup clutch con-sists of three main elements: piston 10, clutch plate 12, and backplate 14. These elements are located between the torque converter cover and the torque converter turbine. The piston and backplate rotate with the

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DESCRIPTION AND OPERATION

verter pump. The clutch plate is located between the piston and the backplate and is splined to the converter turbine.

b

b.. OpOpereratatiionon (Foldout 6). The engagement of the lockup clutch is controlled by the lockup relay valve which derives its lockup signal from the modulated lockup valve. Clutch-apply pressure compresses the lockup clutch plate between the piston and backplate, locking all three together. The converter pump and tur-bine are locked together and provide a direct drive from the engine to the transmission gearing. As rota-tional speed of the output shaft decreases, the relay valve automatically releases the lockup clutch. Refer to Paragraph 2–24

llfor explanation of the hydraulic ac-tion.

2–8. OIL PUMP ASSEMBLY

a.

a. DeDescscririptptioionn(Foldout 7,A). Oil pump assembly 4 consists of three main elements: drive gear 9, driven gear 8, and pump body 7. The oil pump assembly is bolted to front support assembly 22.

b

b.. OpOpereratatiionon(Foldout 7,A). When the torque con-verter rotates, its rear hub drives pump drive gear 9. Gear 9 is in mesh with driven gear 8. As the gears ro-tate, they draw ﬂuid into the oil pump and move the ﬂuid into the hydraulic system.

2–9. OIL PUMP AND FRONT

SUPPORT ASSEMBLY

Oil pump and front support assembly 1 (Foldout 7,A) is bolted to the transmission housing. The front sup-port provides the ground sleeve for the torque con-verter and supports the forward clutch and turbine shaft. The rear side of the front support contains bores for main-pressure regulator valve 13, converter-pres-sure regulator valve 25, and lockup valve 17.

2–10. FORWARD CLUTCH

AND TURBINE SHAFT

a.

a. DeDescscririptptioionn (Foldout 7,B)

1. Forward clutch and turbine shaft assembly 2 connects the converter turbine to the clutches and gearing in the transmission.

2. Piston 16 is retained in housing and shaft as-sembly 3 by piston return spring 17, spring re-tainer 18, and snapring 19.

3. The external tangs of clutch plates 22 engage the slots in the housing and shaft assembly. The internal splines of clutch plates 23 engage forward clutch hub 21, which is splined to main shaft assembly 33 (Foldout 9,A or 9,B). Clutch plates 23 are held in place by fourth clutch driving hub 24, which is retained by snapring 25. PTO drive gear 13 is secured to forward clutch housing 6 by snapring 12. 4. For transmissions after S/N 49489, housing 6

contains centrifugal valve 11, valve spring 10, and valve plug 9. Pin 8 retains these parts in the housing.

b

b.. OpOpereratatioionn (Foldout 7,B)

1. Housing 6 rotates when the converter turbine rotates. Fourth clutch driving hub 24 also ro-tates. Fourth clutch internal-splined plates 4 (Foldout 8,A) are splined to the driving hub and rotate with it.

2. When hydraulic pressure is applied to the pis-ton bore in forward clutch housing 6 (Foldout 7,B), piston 16 compresses plates 22 and 23 against fourth clutch driving hub 24. This locks forward clutch hub 21 to forward clutch hous-ing 6. Hub 21 is splined to main shaft assembly 33 (Foldout 9,A or 9,B).

3. The forward clutch is applied only in forward range operation, and is always paired with an-other clutch (either ﬁrst, second, third, fourth, or low (MT 650, 653 only)). When the con-verter turbine rotates and the forward clutch is applied, the main shaft assembly also rotates. This drives components of the gear unit, which drives the output shaft in any forward range. The speciﬁc forward range depends upon which additional clutch is applied.

4. In neutral or reverse operation, the forward clutch is not applied. Torque from the con-verter turbine rotates only forward clutch hous-ing 6 (Foldout 7,B) and fourth clutch drivhous-ing hub 24.

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MT(B) 640, 643, 650, 653 AUTO MATIC TRANSMISSIONS

5. For transmissions after S/N 49489, centrifugal valve 11 provides a safety feature to prevent over-speeding the torque converter. When the forward clutch housing exceeds a predetermined rotational speed, the centrifugal valve lifts from its seat and exhausts the forward clutch.

2–11. FOURTH CLUTCH

a.

a. DeDescscririptptioionn (Foldout 8,A)

1. The fourth clutch includes housing assembly 13, piston 9 or 10, piston return spring 8, four internal-splined plates 4, four external-tanged plates 5, spring retainer 7, snapring 6, back-plate 3, and snapring 2.

2. Piston 9 or 10 is installed in housing assembly 13 and is retained by spring 8, spring retainer 7, and snapring 6. External-tanged plates 5 en-gage slots in clutch housing assembly 13. In-ternal-splined plates 4 engage splines in fourth clutch driving hub 24 (Foldout 7,B). Plates 4 and 5 are held in place by backplate 3 and snapring 2.

3. The hub of clutch housing 13 splines onto sun gear shaft 27 (Foldout 9,A or 9,B). The outer splines of clutch housing 13 engage internal-splined plates 3 (Foldout 8,B) of the third clutch.

b

b.. OpOpereratatioionn (Foldout 8,A)

1. Internal-splined clutch plates 4 rotate when-ever turbine shaft 5 (Foldout 7,B) and forward clutch housing 6 rotate.

2. When the fourth clutch is applied, piston 9 or 10 (Foldout 8,A) compresses plates 4 and 5 against backplate 3, locking plates 4 and 5 together and, in turn, to clutch housing 13. Clutch housing 13 rotates with the turbine shaft.

3. The fourth clutch is engaged during fourth range (MT 640, 643), ﬁfth range (MT 650, 653), and reverse range operation. In fourth (or ﬁfth) range, the fourth and forward clutches are engaged. Clutch housing 13 drives sun gear and shaft assembly 23 (Foldout 9,A or 9,B) at the same speed that forward clutch hub 21

(Foldout 7,B) drives main shaft assembly 33 (Foldout 9,A or 9,B). The result is direct drive to the output shaft.

4. In reverse range operation, the fourth clutch and the ﬁrst clutch are applied (the forward clutch is released). The fourth clutch operates as described in Step (4). Engagement of the ﬁrst clutch (Foldout 11,A) causes an interac-tion between the planetaries that results in re-verse rotation of the output shaft.

2–12. THIRD CLUTCH, CENTER

SUPPORT, AND SECOND CLUTCH

a.

1. The third clutch is forward of center support housing assembly 13, and the second clutch is rearward of the center support housing assem-bly. Each clutch has six clutch plates. 2. The third clutch includes items 1 through 11.

The second clutch includes items 17 through 28. Center support housing assembly 13 serves both clutches. The front side of the center sup-port housing is bored to receive third clutch piston 9. The rear side is bored to receive sec-ond clutch piston 19. Center support housing assembly 13 includes passages which direct ﬂuid to both of these clutches, and provides lubrication to the fourth clutch assembly. 3. External-tanged plates 4 and 26 engage slots in

the transmission housing and are always sta-tionary. Internal-splined plates 3 of the third clutch engage splines in fourth clutch housing assembly 13 (Foldout 8,A). Internal-splined plates 27 of the second clutch engage splines in front planetary carrier assembly 4 (Foldout 9,A or 9,B).

b.

b. OpeOperatiration of on of ThiThird Clrd Clutcutchh(Foldout 8,B)

1. When the third clutch is applied, piston 9 com-_{presses plates 3 and 4 against backplate 2. This} locks plates 3 (which are splined to the fourth clutch housing) to plates 4 which are station-ary. This holds the fourth clutch housing sta-tionary.

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DESCRIPTION AND OPERATION

2. Sun gear shaft assembly 23 (Foldout 9,A or 9,B) is held stationary through the splines of the clutch housing hub. This causes a reaction within the planetary carrier assemblies which produces a third (MT 640, 643) or fourth (MT 650, 653) range ratio at the output shaft. Input torque for the gearing is transmitted through the engaged forward clutch and the transmis-sion main shaft.

c.

c. OpeOperatiration oon of Sf Seconecond Cd Clutlutchch(Foldout 8,B) 1. When the second clutch is applied, piston 19

compresses plate 26 and 27 against backplate 28. This locks plates 27, which are splined to front planetary carrier 4 (Foldout 9,A or 9,B), to plates 26 (Foldout 8,B) which are stationary. 2. The front planetary carrier is held stationary. This causes a compound reaction within the planetary gearing which produces a second range (MT 640, 643) or third range (MT 650, 653) ratio at the output shaft. Input torque for the gearing is transmitted through the engaged forward clutch and transmission main shaft.

2–13. FIRST CLUTCH

a.

1. The ﬁrst clutch includes piston 11, six internal-splined plates 3, and six external-tanged plates 4. 2. In the MT 640, 643, piston 11 is positioned in

rear cover 6 (Foldout 12,A). In the MT 650, 653, piston 11 is positioned in adapter housing 3 (Foldout 11,B). The external tangs of plates 4 (Foldout 11,A) engage slots in the transmission housing and are always held stationary. The splines of plates 3 engage rear planetary ring gear 5 (MT 650, 653) or 14 (MT 640, 643). Piston 11 is retained by twenty-six piston re-turn springs 10, retainer 9, and snapring 8.

b

b.. OpOpereratatioionn (Foldout 11,A)

1. When the ﬁrst clutch is applied, piston 11 com-presses plates 3 against plates 4. This locks in-ternal-splined plates 3 to external-tanged plates 4, which are stationary. Plates 3 are splined to

ring gear 5 or 14, and hold the ring gear sta-tionary.

2. The stationary ring gear causes a reaction within the planetary gearing to produce either ﬁrst range (MT 640, 643), second range (MT 650, 653), or reverse, depending on the driving mem-ber in the gear set. In ﬁrst range (MT 640, 643), the driving member is rear planetary sun gear 37 (Foldout 9,A), which is driven by the transmis-sion main shaft and the engaged forward clutch. In second range (MT 650, 653), the driving member is rear planetary sun gear 36 (Foldout 9,B). First (or second) range is produced by the action of one planetary. In reverse range, the driving member is sun gear shaft assembly 23 (Foldout 9,A or 9,B) which is driven by the en-gaged fourth clutch and the forward clutch housing. Reverse range is accomplished by compound action of two planetaries.

2–14. PLANETARY GEAR UNIT

NOTE: NOTE:

Because gearing components for MT 640, 643 and Because gearing components for MT 640, 643 and MT 650, 653 models are nearly identical, most MT 650, 653 models are nearly identical, most ref-erences below are to the MT 640, 643 illustration erences below are to the MT 640, 643 illustration (Foldout 9,A). The MT 650, 653 gearing is shown in (Foldout 9,A). The MT 650, 653 gearing is shown in

Foldout 9,B. Foldout 9,B.

a.

1. The gear unit and main shaft assembly in-cludes all of the gears in the transmission, ex-cept the rear planetary ring gear 5 or 14 (Fold-out 11,A) and the low range gearing (Fold(Fold-out 11,B).

2. Three planetary gear sets are included in the assembly. These are called front planetary, cen-ter planetary, and rear planetary. The planetary sets are so designated because of their posi-tions in relation to the transmission and to each other.

3. The front planetary includes sun gear 2, front carrier assembly 4, and ring gear 14. The cen-ter planetary includes sun gear and shaft as-sembly 23, planetary carrier asas-sembly 15, and ring gear 32. The rear planetary includes sun

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MT(B) 640, 643, 650, 65 3 AUTO MATIC TRANSMISSIONS

gear 37 and carrier assembly 40. Also included is ring gear 14 (Foldout 11,A) for MT 640, 643 models or ring gear 5 for MT 650, 653 models. 4. The three planetaries are connected by sun gear shaft assembly 23 (Foldout 9,A), main shaft assembly 33, and planetary connecting drum 30. This interconnection of planetary in-put, reaction, and output components produces four forward speeds and one reverse speed.

b

b.. OpOpereratatioionn(Foldout 9,A)

1. The front planetary, together with the center planetary, produces second range (MT 640, 643), or third range (MT 650, 653), when the forward and second clutches are engaged. 2. The center planetary is active in second and third

(MT 640, 643), or third and fourth (MT 650, 653), and reverse ranges. In second range (third range in MT 650, 653), it is compounded with the front planetary, as described in Step (1). 3. The center planetary produces third range

(MT 640, 643), or fourth range (MT 650, 653), when the forward and third clutches are engaged.

4. The center planetary is locked with the front planetary and the rear planetary to produce fourth range (MT 640, 643), or ﬁfth range (MT 650, 653), when the forward and fourth clutches are engaged.

5. The center planetary is compounded with the rear planetary to produce reverse range when the fourth and ﬁrst clutches are engaged. 6. The rear planeta ry is activ e in ﬁrst range

(MT 640, 643), or second range (MT 650, 653), and reverse range operation.

7. The rear planetary is locked with the front and center planetaries to produce fourth (or ﬁfth) range as explained in Step (4).

8. The rear planetary is compounded with the center planetary to produce reverse range as explained in Step (5).

9. The rear planetary acts alone to produce ﬁrst range (MT 640, 643), or second range (MT 650, 653), when the ﬁrst and forward clutches are en-gaged.

NOTE: NOTE:

In fourth range (MT 640, 643), or fifth range (MT 650, In fourth range (MT 640, 643), or fifth range (MT 650, 653), all three planetaries rotate as a unit because the 653), all three planetaries rotate as a unit because the forward and fourth clutches are engaged. This gives forward and fourth clutches are engaged. This gives

direct drive through the transmission. direct drive through the transmission.

2–15. LOW CLUTCH (MT 650, 653 Only)

a.

1. The low clutch includes piston 23, ﬁve inter-nal-splined plates 18, and six external-tanged plates 17.

2. The piston is housed in rear cover assembly 13 (Foldout 12,B). The external tangs of plates 17 (Foldout 11,B) engage slots in adapter housing 3 and are held stationary. The internal splines of plates 18 engage the splines of planetary carrier assembly 8. Piston 23 is retained by twenty-six piston return springs 22, retainer 21, and snapring 20.

b

b.. OpOpereratatioionn (Foldout 11,B)

1. When the low clutch is released, internal-splined plates 18 are free to rotate. This allows low planetary carrier assembly 8 to rotate. The low clutch is released in neutral, reverse, sec-ond, third, fourth, and ﬁfth range operation.

2. When the low clutch is applied, piston 23 com-presses plates 17 and 18 against adapter hous-ing 3. This locks internal-splined plates 18 to external-tanged plates 17, which are stationary. Plates 18, splined to low planetary carrier as-sembly 8, hold it stationary. This causes a reac-tion within the planetary which produces ﬁrst range ratio at the output shaft. Input torque for the gearing is transmitted through the engaged forward clutch and transmission main shaft.