Description
This 300 page, Allison HT 700 Series transmission manual was originally published September 1981 and is out of print. This is a high quality printed reproduction of the original. This Allison HT 700 Series Transmission Service Manual from Detroit Diesel Allison provides service, maintenance and repair information for the Allison transmission HT 700D Series including repair information for the following transmissions:
HT 740D
HT 750CRD
HT 750DRD
HT 750DRD DB
HT 754 CRD
SA 1270H
Allison HT 700 Series Manual Table of Contents
Allison HT 700 Series General Information
Scope Of Manual
Coverage
Illustrations
Maintenance Information
Supplementary Information
Ordering Parts
Transmission Nameplate
Parts Catalog
General Description
Automatic Shifting
Torque Converter
Lockup Clutch
Hydraulic Retarder
Power Takeoff Provisions
Planetary Gearing, Clutches
Output Transfer Housing (dropbox)
Output Disconnects
Operating Instructions
Vehicle-related Controls
Neutral (n)
Forward Drive Ranges
Reverse (r)
Range Selection
Hydraulic Retarder
Towing
Specifications And Data
Allison HT 700 Series Description And Operation
Scope Of Section 2
Designation Of Clutches, Planetary Gear Sets
Necessary For Clarity Of Description
Clutch Designations
Planetary Gear Set Designations
Transmission Mounting
Straight-through Models
Transfer Gear Case (dropbox) Models
Input Drive
Direct Drive
Remote Drive
Torque Converter
Description
Operation
Lockup Clutch
Description
Operation
Torque Converter Housing
Hydraulic Retarder
Oil Pump Assembly, Description, Operation
Front Support And Valve Assembly
Forward Clutch And Turbine Shaft
Function Differs Among Models
Description
Operation
Fourth Clutch
A Function Differs Among Models
B Description
C Operation
Allison HT 700 Series Second, Third Clutches, And Center Support
A Function Differs Among Models
B Description
C Operation Of Third Clutch
D Operation Of Second Clutch
Allison HT 700 Series First Clutch
A Function Differs Among Models
B Description
C Operation (ht 740d)
D Operation (ht 750crd)
E Operation (ht 750drd)
Allison HT 700 Series Low Clutch
A Function Differs Among Models
B Description
C Operation (ht 750crd)
D Operation (ht 750drd)
Planetary Gearing (ht 740d)
A Description
B Operation
Planetary Gearing (ht 750crd)
A Description
B Operation
Planetary Gearing (ht 750drd)
A Description
B Operation
Allison HT 700 Series Speedometer Drive (straight-through Models)
A Description
B Operation
Governor
A Description
B Operation
Control Valve Assembly
A Description
B Operation
Low Shift And Trimmers Valves
A Description
B Operation
Lockup Cutoff Valves
A Description
B Operation Ht 740d
C Operation Ht 750drd
Allison HT 700 Series Second Gear Start (ht 740, Ht 750crd)
A Description
B Forward Gear Operation
C First Gear Operation
D Reverse Gear Operation (early Models)
E Reverse Gear Operation (late Models)
Oil Pan And Oil Filter
A Description
B Function
Rear Adapter Housing
Rear Cover
Transfer Gear Housing Adapter
Transfer Gear Housing (dropbox)
Manual Disconnect Clutch
Allison HT 700 Series Hydraulic System
A System Functions
B System Schematics
C Oil Filter, Pump Circuit
D Main-pressure Circuit
E Converter, Cooler, Lubrication Circuit
F Selector Valve, Forward Regulator Circuits
G Rear Governor Circuit
H Modulator Pressure Circuit
I Trimmer Regulator Valve
J Trimmer Valves
K Lockup Circuit (actuated By Front Governor Ht 740, Ht 750)
1 Lockup Circuit (actuated By Rear Governor Ht 740d)
M Priority Valve
N Clutch Circuits, Drive Ranges (ht 740d)
0 Clutch Circuit, Drive Ranges (ht 750crd)
P Clutch Circuit, Drive Ranges (ht 750 Drd)
Q Automatic Upshifts
R Automatic Downshifts
S Downshift And Reverse Inhibiting
Allison HT 700 Series Torque Paths Through Transmission (ht 740d)
A Converter Operation
B Lockup Operation
C Neutral Operation
D First-gear Operation
E Second—gear Operation
F Third—gear Operation
G Fourth-gear Operation
H Reverse Gear Operation
Allison HT 700 Series Torque Paths Through Transmission (ht 750crd)
A Converter Operation
B Lockup Operation
C Neutral Operation
D First-gear Operation
E Second-gear Operation
F Third—gear Operation
G Fourth-gear Operation
H Fifth-gear Operation
1 Reverse-gear Operation
Allison HT 700 Series Torque Paths Through Transmission (ht 750drd)
A Converter Operation
B Lockup Operation
C Neutral Operation
D First-gear Torque Path
E Second-gear Operation
F Third-gear Operation
G Fourth-gear Operation
H Fifth-gear Operation
I Reverse-gear Operation
Torque Paths Through Transmission (ht 750drd Db)
3 Allison HT 700 Series Preventive Maintenance
Scope Of Section 3
Inspection And Care
Dipstick Calibration
A Dipstick Calibration
B Six-inch Deep Oil Pan
C Seven And Eight And One Half-inch Deep Oil Pan
D Full And Add Marks
E Dropbox Models
Oil Level Checks
A Importance Of Proper Level-
B Foaming And Aerating
C Protect Fill Pipe
D Oil Level Check Procedure
E Dropbox Oil Check
Oil Specifications
A On-highway Applications
B Off-highway Applications
C Dropbox
D Auxiliary Preheat-dexron
E Auxiliary Preheat—c-3 Oils
Changing The Oil And Filters
A Cleanliness
B Change Internal
C Oil Capacity
D Oil And Oil Filter Change Procedure
Oil Contamination
A Examine At Oil Change
B Metal Particles
C Coolant Leakage
D Auxiliary Filter (models Without Hydraulic Retarder)
Breather
Linkage
A General Information
B Selector Lever Installation And Adjustment
C Retarder Linkage Adjustment
D Mechanical Actuator Adjustment
Shift Speed Adjustments
A Calibrated On Test Stand Or In Vehicle
B Location Of Adjusting Components
C Checks Before Adjusting Shift Points
D Calibration By Road Test Method
E Alternate Method Using Speedometer Readings
F Calibration By Test Stand Method
Allison HT 700 Series External Lines And Oil Cooler
A External Lines
B Oil Cooler
Transmission Stall Test
A Purpose
B Procedure
Preservation And Storage
A Storage, New Transmission (prior To Installation)
B Preservation Methods
C Storage, One Year—without Oil
D Storage, One Year—with Oil
E Restoring Transmission To Service
Replacing Output Shaft Seal (in Vehicle)
A Remove Seal
B Install Seal
Replacing Manual Disconnect Output Seal
A Remove Seal
B Install Seal
Replacing Output Shaft Bearing, Speedometer Drive Gear
(straight-through Models Only)
A Remove Bearing And Gear
B Install Gear And Bearing
Checking Oil Pressures
Troubleshooting—before Removal Or Operation
A Visual Inspection
B System Knowledge
Troubleshooting—during Operation
A Determine Trouble Cause
B Properly Tuned Engine
Troubleshooting—after Removal
Troubleshooting
4 Allison HT 700 Series General Overhaul Information
Scope Of Section 4 Tools And Equipment
A Improvised Tools And Equipment
B Special Tools
C Mechanic’s Tools, Shop Equipment
Replacement Parts
A Ordering Information
B Parts Normally Replaced
Careful Handling
Cleaning, Inspection
A Dirt Causes Malfunction
B Cleaning Parts
C Cleaning Bearings
D Keeping Bearings Clean
E Inspecting Cast Parts, Machined Surfaces
F Inspecting Bearings
G Inspecting Bushings, Thrust Washers
H Inspecting Oil Seals, Gaskets
I Inspecting Gears
J Inspecting Splined Parts
K Inspecting Threaded Parts
1 Inspecting Snaprings
M Inspecting Springs
N Inspecting Clutch Plates
0 Inspecting Swaged, Interference-fit Parts
P Inspecting Balls In Clutch Housings
Q Inspecting Sealing Surfaces
Allison HT 700 Series Assembly Procedures
A Clutches, Pistons
B Parts Lubrication
C External Plugs, Hydraulic Fittings
D Grease Used For Assembly
E Sealring Compounds, Nonsoluble Greases
F Lip-type Oil Seals
G Interference-fit Parts
H Sleeve-type Bearings
1 Bearings (ball Or Roller)
Removing (or Installing) Transmission
A Drain Oil
B Check Linkages And Lines
C Clean Transmission
D Reconnect At Installation
Wear Limits
Spring Specifications
Torque Specifications
5 Allison HT 700 Series Disassembly Of Transmission
Scope Of Section 5
Removing External Components
A Mounting Transmission In Overhaul Stand
B Removing External Components
Removal Of Manual Output Disconnect Assemblies (dropbox Models)
Separating Dropbox From Transmission
A Removal Of Transfer Gear Housing
Removing Remote Cover, Flywheel And Lockup Clutch
A Removing Remote Front Cover
B Removing Flywheel, Lockup Clutch
Removing Oil Pan, Filter, Valve Body (ht 740d)
A Oil Pan, Filter
B Valve Body
Removing Oil Pan, Filter, Valve Bodies (ht 750)
A Oil Pan, Filter
B Valve Bodies
Allison HT 700 Series Removing Torque Converter And Pto Components
A Converter Stator, Pump
B Scavenge Pump Assembly
C Power Takeoff
Removing Converter Housing
A Housing With 2-bolt Top Cover (no Retarder)
B Housing With 2-bolt Top Cover (with Retarder)
C Housing With 8-bolt Top Cover (no Retarder)
D Housing With 8-bolt Top Cover (with Retarder)
Removing Retarder Valve Body, Housing, And Front Support And
Sleeve Assembly
A Retarder Valve Body Assembly
B Retarder Housing, And Front Support And Sleeve Assembly
Removing Forward, Fourth, Third Clutches
A Forward, Fourth Clutches
B Third Clutch
Removing Center Support, Gear Unit, Second Clutch (ht 740 Or Ht 750drd)
A Center Support
B Gear Unit
C Second Clutch
Removing Rear Components (ht 740d)
A Governor
B Rear Cover
C First Clutch
Removing Rear Components (ht 750crd)
A Governor
B Rear Cover
C Low Planetary And Clutch
D First Clutch And Ring Gear
Allison HT 700 Series Removing Center Support, Gear Unit, Second Clutch (ht 750crd)
A Supporting Gear Unit
B Removing Components
Removing Rear Components (ht 750drd)
A Governor
B Rear Cover
C Low Planetary And Clutch
D First Clutch And Ring Gear
6 Allison HT 700 Series Rebuild Of Subassemblies
Scope Of Section 6
General Information For Subassembly Rebuild
A Tools, Parts, Methods
B Cleaning, Inspection A
C Torque Specifications
D Wear Limits, Spring Data
E Plugs And Fittings
F Clutch Pack Procedure
G Sleeve-retaining Compound
Flywheel, Lockup Clutch, Converter Turbine
A Disassembly
B Rebuilding Allison HT 700 Series Converter Turbine Assembly
C Assemb1y
Torque Converter Stator Assembly
A Disassemb1y
B Rebuilding Stator Assembly
C Assembly
Torque Converter Pump Assembly
A Disassembly
B Assembly
Control Valve Body Assembly
A Disassembly
B Assembly
Low Trimmer Valve Body Assembly'(ht 750)
A Disassembly
B Assembly
Low Shift Valve Body Assembly (ht 750
A Disassembly
B Assembly
Lockup Cutoff Valve Body Assembly
A Disassembly
B Assembly
Converter Housing With 2-bolt Top Cover, Front Support, Oil Pump”
A Disassembly
B Assembly
Converter Housing With 2-bolt Top Cover, Retarder Plate, Oil Pump
A Disassembly
B Assembly
Converter Housing With 8-bolt Top Cover, Retarder Plate, Oil Pump
A Disassembly
B Assembly
Converter Housing With 8-bolt Top Cover, Front Support, Oil Pump
A Disassembly
B Assembly
Scavenge Oil Pump, Pto Idler Gear
A Disassembly
B Assembly
Retarder Valve Body Assembly
A Disassembly
B Assembly
Retarder Housing, Front Support
A Disassembly
B Assembly
Forward Clutch And Turbine Shaft
A Disassembly
B Assembly
Fourth Clutch Assembly
A Disassembly
B Assembly
Allison HT 700 Series Center Support Assembly
A Disassembly
B Assembly
Gear Unit And Main Shaft Assembly (ht 740d)
A Disassembly
B Replacing Sun Gear Shaft Bushings
C Assembly
Gear Unit And Mainshaft Assembly (ht 750drd, Ht 750 Drd Db)
A Disassembly
B Assembly
Gear Unit And Main Shaft Assembly (ht 750crd) A 9 Disassembly
B Assembly
Allison HT 700 Series Planetary Carrier Assemblies
A Assembly Inspection
B Removal, Installation Of Pinion Components
C Replacing Bushing In Front Planetary Carrier Assemblies
Low Sun Gear And Hub (ht 750drd, Ht 750drd Db)
Adapter Housing Assembly (ht 750)
A Disassembly
B Assembly
Rear Cover Assembly
A Disassembly
B Assembly
Transmission Housing
A Disassemb1y
B Assembly
Transfer Gear Housing And Gears
A Disassembly
B Assembly
Transfer Gear Housing Adapter, Output Shafts A Disassembly
Be Assembly
Flex Disk Assembly
A Disassembly
B Assembly
Governor
A Disassemb1y
B As S Emb1y
Output Manual Disconnect Assemblies
A Disassemb1y
B As Semb1y
Establishing Clutch Clearances
A Two Methods
B Forward Clutch
C Fourth Clutch
D First Clutch (ht 740), Low Clutch (ht 750)
E First Clutch (ht 750)
F Second And Third Clutches
7 Allison HT 700 Series Assembly Of Transmission
Scope Of Section 7
Clutch Clearances
A Preparation Procedure
B Determine Plate Thickness
Establishing Clutch Clearances, Selecting Center Support Snapring (ht 740d)
A First Clutch Clearance
B Selecting Center Support Snapring
C Second Clutch Clearance
Establishing Clutch Clearances, Selecting Center Support Snapring (ht 750crd, Drd, Drd-db)
A Low And First Clutch Clearances
B Selecting Center Support Snapring
C Second Clutch Clearance
Installing Rear Components (ht 740d)
A First Clutch
B Rear Cover Assembly
Installing Allison HT 700 Series First Clutch, Gear Unit, Second Clutch, Center Support (ht 750crd)
A First Clutch, Rear Planetary Ring Gear
B Gear Unit, Second Clutch, Center Support
Installing Rear Components (ht 750crd)
A Adapter Housing, Low Clutch, Low Ring Gear
B Low Planetary, Rear Cover Assembly
Installing Gear Unit, Second Clutch, Center Support (ht 740d)
A Gear Unit, Second Clutch
B Center Support
Installing Rear Components (ht 750drd, Drd Db)
A First Clutch And Ring Gear
B Adapter Housing, Low Clutch And Planetary Carrier
C Rear Cover Assembly
D Temporary Installation Of Transfer Gear Housing Adapter Assembly
Installing Gear Unit, Second Clutch, Center Support (ht 750drd, Drd Db)
A Gear Unit, Second Clutch
B Center Support
Installing Fourth, Third, Forward Clutches
A Fourth Clutch, Third Clutch
B Forward Dutch
Installing Torque Converter Housing (models Without Retarder)
A Housing With 2-bolt Top Cover
B Housing With 8-bolt Top Cover
Installing Allison HT 700 Series Hydraulic Retarder Components
A Housing, Front Support
B Rotor Components
Installing Torque Converter Housing (models With Retarder)
A Housing With 2-bolt Top Cover
B Housing With 8-bolt Top Cover
Installing Torque Converter Pump, Stator Assemblies
A Pump Assembly
B Stator Assembly
Installing Valve Body, Oil Filter, Oil Pan (ht 740d)
A Valve Body
B Oil Filter, Oil Pan
Installing Valve Bodies, Filter, Oil Pan (ht 750crd, Drd, Drd Db)
A Valve Bodies
B Oil Filter, Oil Pan
Installing Flywheel, Lockup Clutch, Torque Converter Turbine
A Align Flywheel For Installation
B Installation
C Transmission Front Cover
Installing Allison HT 700 Series External Components
A External Components
B Retarder Valve Body
Installation Of Transfer Gear Housing Adapter Assembly, Transfer Gear Housing, Disconnect Clutches, Output, Input Flanges
A Transfer Gear Housing Adapter Assembly
B Transfer Gear Housing (dropbox)
C Output Manual Disconnect Clutches
D Installing Output, Input Flanges
E Bearing Retainer & Cover
Removing Allison HT 700 Series Transmission From Overhaul Stand
Checking Shift Points
Power Takeoff Components
A Existing Installation
B New Installation
8 Allison HT 700 Series Wear Limits And Spring Data
Scope Of Section 8
Allison HT 700 Series Wear Limits Data
A Maximum Variations
B Cleaning, Inspection
C Bearings, Bearing Journals, Bores
D Gears
E Splines
F Hook-type Sealrings
G Oil Seals
Spring Data
Foldouts (back Of Manual)
Cross-section Views
1 Model Ht 740d Transmission
2 Model Ht 750crd Transmission
3 Model Ht 750drd Transmission
4 Model Ht 750drd Db Transmission
Schematic Views
5 Model Ht 740d Transmission Hydraulic System
6 Model Ht 750crd Transmission Hydraulic System
7 Model Ht 750drd Transmission Hydraulic System
8 Model Ht 750drd (all-range Lockup) Transmission Hydraulic System
Exploded Views
Flex Disc And Flywheel Assemblies
Transmission Front Cover, Remote Mount
Lockup Clutch And Torque Converter
Oil Pump And Converter Housing (models Without Retarder)
Converter Housing And Ground Sleeve
Converter Housing (with Retarder, No Pto)
Scavenge Oil Pump And Power-takeoff Driven Gear
Retarder And Retarder Housing
Front Support And Valve Assembly Forward Clutch Assembly
Fourth-clutch Assembly
Third-clutch, Center Support And Second Clutch
Gear Unit And Main Shaft Assembly (ht 740d)
Gear Unit And Main Shaft Assembly (ht 750crd)
Gear Unit And Main Shaft Assembly (ht 750drd)
Transmission Housing, Oil Filter And Six-inch Deep Oil Pan
Transmission Housing, Oil Filter And Seven-inch Oil Pan
Transmission Housing, Oil Filter And Eight And One-half Inch Oil Pan
First Clutch
Adapter Housing, Low-clutch Plates And Low Carrier (HT 750crd)
Adapter Housing, Low-clutch Plates And Low Carrier (HT 750drd)
Low-clutch Piston, Rear Adapter Housing And Governor
First And Low Piston, Rear Cover, Output Shaft And Governor
Control Valve Assembly
Lockup Cutoff, Low Shaft And Low Trimmer Valve Body Assemblies
Retarder Valve Body Assembly
Transfer Gears And Transfer Gear Driven Shaft
Transfer Gear Housing
Rear Output Disconnect Clutch
Front Output Disconnect Clutch
