CONSTRUCTION EQUIPMENT SERVICE TRAINING
1650K & 1850K SERIES
CRAWLER TRACTORS
SECTION 2A TORQUE CONVERTER
Form 5080 REV 04/2002
CASE CORPORATION CASE CANADA CORPORATION 2000 Case Corporation
700 STATE STREET 3350 SOUTH SERVICE ROAD All Rights Reserved
RACINE, WI 53404 U.S.A. BURLINGTON, ON L7N 3M6 CANADA Printed in U.S.A.
TABLE OF CONTENTS
TABLE OF DEFINITIONS----------------------------------------------------------------------------------4
COMPONENT SPECIFICATIONS:---------------------------------------------------------------------------4
GENERAL INFORMATION---------------------------------------------------------------------------------5
HOW A TORQUE CONVERTER WORKS------------------------------------------------------------------6
TORQUE CONVERTER COMPONENTS-------------------------------------------------------------------10
TORQUE CONVERTER SCHEMATIC---------------------------------------------------------------------18
TORQUE CONVERTER TESTING-------------------------------------------------------------------------20
TORQUE CONVERTER
OBJECTIVES
After completion of this section of the training manual, the trainee will be able to accomplish
the following:
Know the location of the torque converter components.
Know how all the hydraulic and electrical components function.
Be able to diagnose and systematically troubleshoot defects in Drive system.
Keep an eye out for symbols, which will alert you to special information.
Wait a Minute… This symbol will preface a frequently asked question.
REMEMBER: This symbol will preface a tip that may make your job more
efficient.
IMPORTANT: This symbol will preface a tip that you should definitely not
ignore.
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TORQUE CONVERTER
TABLE OF DEFINITIONS
COMPONENT SPECIFICATIONS:
Hydraulic Components
System Specification
Normal Operating Temperature 110-245 oF (43-118oC)
Torque Converter Pump, Rear Section 13.2 gal/min (51.4 L/min)
Transmission Pump, Front Section 17.7 gal/min (67 L/min)
Torque Converter Scavenger Pump 5.3 gal/min (22 L/min
Torque Converter Relief Valve 150 PSI (10.5 bar)
Suction Line Filter 100 Microns, 1000 hr. service intervals
High Idle (engine) 1650K 2300 RPM
Converter Stall RPM, 1940-2080 RPM
Transmission
Converter Total Stall 1660-1860 RPM
High Idle (engine) 1850K 2200 RPM
Converter Stall RPM, 1680-1820 RPM
Transmission
Converter Total Stall 1400-1600 RPM
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TORQUE CONVERTER
GENERAL INFORMATION
Crawler dozers, needing a considerable capacity of adapting to the resistance to be
overcome during their operation cycle, must be capable of considerable performance
elasticity, meaning a wide variation range of torque and speed.
The most suitable device to solve this problem is coupling a second Hydraulic Transmission
to a traditional transmission, providing a wide continuous and automatic range of variation of
the transmission ratio.
This device is designated as a “Torque Converter”. It is a mechanism made of a succession
of hydraulic wheels through which the power is transmitted by the dynamic action of a fluid
moving inside a closed circuit.
In it, the torque change is obtained by the presence of a fixed reacting element (STATOR)
and under the effect of the driven wheel (TURBINE) related to the powering wheel
(IMPELLER). The greater the speed difference between the impeller and turbine, the greater
is the torque multiplication.
The torque converter is mounted on the engine flywheel receiving oil from the torque
converter pump and then flows through the cooler to transmission lubrication.
Torque Convert Models
Component Model
1650K 1850K
Brand Twin-Disc Twin-Disc
Model 13”, 6F-1301-MS 400 15”, 6F-1507 MS 335
Number of Elements 3, Impeller, Turbine, Stator 3, Impeller, Turbine, Stator
Torque Ratio at Stall 2.34:1 2.28;1
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TORQUE CONVERTER
HOW A TORQUE CONVERTER WORKS
.
To understand what a torque converter is, it is
necessary to know what is meant by torque. Torque is
simply the effort required to produce rotation. Winding a
bucket up out of a well is a typical example of torque.
The engine supplies the torque for any crawler. Its
object is to rotate the sprocket wheels and place the
crawler in motion.
First, let’s use as an example, an engine with a direct
mechanical connection to the sprocket wheels. The
engine is designed to turn a fixed load (the sprocket
wheels) at a fixed speed.
This works fine until the balance is upset. When the
load at the sprocket wheels becomes greater than the
load or torque capacity of the engine, the engine stalls.
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TORQUE CONVERTER
HOW A TORQUE CONVERTER WORKS
The limitation of this arrangement is clear. Now let’s
add a gear-type transmission between the engine and
sprocket wheels to make the crawler more versatile.
The addition of gears between the engine and sprocket
wheels allow the operator to manually balance the
engine torque to the load by means of gear ratios.
However, this arrangement has a limitation, too. If the
operator is too slow or guesses wrong in trying to
balance the gear ratio with the load, the engine lugs
down and stalls because there are a limited number of
ratios and the balance must be reached very quickly.
Now let’s add a torque converter between the engine
and gear-type transmission.
With a torque converter mounted between the engine
and transmission, the engine turns a hydraulic pump
(the impeller) which forces oil through a passage
against a paddle wheel (the turbine). This causes the
turbine to rotate. The turbine rotates the output shaft to
the transmission – thus the transmission gears and
sprocket wheels also rotate.
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TORQUE CONVERTER
HOW A TORQUE CONVERTER WORKS
The engine is still operating at a fixed speed, but will not
stall when the load demand from the sprocket wheels
increases because it is not mechanically connected to
the transmission.
As the load on the turbine increases, more oil is
deflected off the turbine blades as it becomes harder to
rotate and slows down. The oil that is deflected off the
turbine does not flow back to the reservoir in the
transmission, but is guided back to the impeller by the
blades of the stator. Thus the oil being circulated by the
impeller is driven an additional push by the redirected oil
from the stator.
This process is known as “torque multiplication”. The oil
from the impeller is given an added push from the oil
coming off the stator, which combines to increase the
turning capacity of the turbine.
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TORQUE CONVERTER
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TORQUE CONVERTER
TORQUE CONVERTER COMPONENTS
1 Torque Converter Case 6 To Converter Cooler Then To Transmission Lube
2 Transmission Relief 7 Scavenging Pump
3 To Transmission Relief Cartage 8 Torque Converter Relief Cartage
4 Transmission Pump 9 To Transmission Lube
5 Converter Charge Pump 10 Converter Pressure Relief Valve
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TORQUE CONVERTER
TORQUE CONVERTER COMPONENTS
Torque Converter Case, (1)
The torque converter housing contains the engine flywheel, torque converter and gear drives
for the hydraulic pumps.
Torque Converter Pump, (5)
The torque converter pump provides the oil supply for the operation of the torque converter
and transmission lubrication. The pump is the rear portion of a dual gear pump assembly,
the front section being for the transmission operations and the rear being for the torque
converter. The pump is rated at 13.2 gpm (51.4 L/m).
Pressure Relief Valve, (10)
The pressure relief valve controls the torque converters supply pressure and the transmission
operating pressure. The converter portion is adjustable using shims to a pressure of 150 PSI
(10.5 bar).
Torque Converter Discharge, (6)
The torque converter discharge port directs the used oil from the torque converter to the
converter oil cooler and then on to transmission lubrication. The port also contains the
transmission temperature switch that is monitoring the converter temperature.
Scavenger Pump, (7)
The scavenger pump draws the oil out of the torque converter housing, keeping the housing
dry, the oil is sent to the transmission case.
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TORQUE CONVERTER
TORQUE CONVERTER COMPONENTS
1 Torque Converter Housing
2 Turbine
3 Stator
4 Impeller
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TORQUE CONVERTER
TORQUE CONVERTER COMPONENTS
Torque Converter Housing, (1)
The torque converter housing contains the torque converter components and uses an
external gear that meshes into the engine flywheel to turn it.
Turbine, (2)
The turbine is connected to the output shaft to turn the transmission. The turbine is driven
through an oil coupling that is created by the impeller throwing oil against it.
Stator, (3)
The stator is used to redirect oil back against the impeller, compounding the force that the
impeller has to throw the oil against the turbine.
Impeller, (4)
The impeller is driven by the torque converter housing at engine speed, transmitting the
engine horsepower, through an oil coupling, to the turbine.
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TORQUE CONVERTER
Torque Converter Operation
Torque Converter and Transmission Pumps
1 Torque Converter
Pump
2 Drive Coupling
3 Transmission Pump
4 Drive Shaft
Suction Line Filter
1 Retaining Nut
2 O’Ring
3 Cover
4 Stud
5 Magnetic Rod
6 Spring
7 Circlip
8 Gasket
9 Base
FA Steel Mesh Element
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TORQUE CONVERTER
TORQUE CONVERTER OPERATION
Torque Converter and Transmission Tandem Pumps
The torque converter auxiliary pump drive gear drives the tandem pump assembly at a speed
greater then engine speed (approximately 2650 RPM at high idle). The two pumps are
connected with an internal drive coupling (2). The front section (3) supplies oil for the
transmission operations and the rear section (1) supplies oil for the torque converter
operations as well as the torque converter cooler to provide transmission cooling and
lubrication.
Suction Line Strainer
The transmission housing provides the reservoir for both pumps. Both pumps pull oil out of
the transmission through the suction line filter. The filter is steel mesh (FA) with 100 micron
rating to provide protection for the pumps. The element requires cleaning every 1000 hours
of operation and has a magnetic rod (5) to retain any metal particles that may get through the
element.
The converter pump’s out put is directed to the pressure relief valve, see next page.
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TORQUE CONVERTER
TORQUE CONVERTER COMPONENTS
Pressure Relief Valve
1 Valve Seat, Torque Converter
2 End Plug, Transmission Pressure
3 Transmission Pressure Sensor
4 Transmission Pressure “OUT”
5 Torque Converter Supply “IN”
6 To Transmission Lube
7 To Torque Converter
8 Plunger
9 Spring
10 Adjusting Shims
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TORQUE CONVERTER
TORQUE CONVERTER COMPONENTS
Pressure Relief Valve
REMEMBER: the pressure relief valve has two separate circuits and relief
spools. One circuit is for the torque converter pump operation and one for the
transmission pump operation.
The torque converter auxiliary pump, converter and cooler are protected with the pressure
relief valve.
Oil is supplied to the inlet port (5) from the torque converter pump and goes out to the
converter through port (7). When the torque converters oil supply has been satisfied the
pressure will begin to build up in the system. The rise in pressure is monitored by the torque
converter relief plunger (8). If the pressure is not correct add or remove shims (10) as
required. When the plunger shuttles against the spring, the excess oil will be directed to the
transmission lubrication circuit (6).
As the torque converter operates there will be normal loses in the converter, so there will be a
constant oil flow through the converter keeping it charged and cooled. As the converter
losses build up the converter housing will fill, a scavenger pump is used to pull the oil out of
the housing, directing it to the torque converter cooler. The oil is then directed from the
cooler to the transmission for lubrication and cooling, this oil combines with the relief valve’s
discharge oil.
Normally most of the torque converter pump’s flow will be going through the converter and
cooler and not the pressure relief valve.
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TORQUE CONVERTER
TORQUE CONVERTER SCHEMATIC
1 Torque Converter 6 Transmission Case 10 Transmission Relief
2 To Transmission Lube 7 Transmission Pump 11 Converter Housing Drain
3 Converter Relief 8 Converter Cooler 12 Scavenging Pump
4 Convert Pump 9 Transmission Filter 13 Brake Pump
5 Suction Screen
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TORQUE CONVERTER
TORQUE CONVERTER SCHEMATIC
The transmission provides the reservoir for the torque converter and transmission pumps. Oil
is drawn out the bottom of the transmission case through a filtering screen (5). The screen is
to be serviced by removing and cleaning the element and magnetic rod with solvent and
reinstalling.
The oil is drawn into the torque converter pump. The pump directs its total output to the
torque converter relief valve (3). At the relief valve the oil is directed into the converter, if the
converter pressure rises above the valve setting, the excess oil is routed through the relief
valve to the transmission lubrication (2). The valve has an external bleed off line that
prevents the spool from hydraulically lock, the oil being bled off will help to lube the pump
drives.
As the torque converter is operating the oil will be heated, depending on the amount of load
being transmitted through the converter, and require cooling. The return side of the converter
will be directed to the converter cooler (8), which is mounted on the left-hand side of the side
by side radiator. The cooled oil will then be used to lubricate and cool the transmission.
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TORQUE CONVERTER
TORQUE CONVERTER TESTING
The performance of the torque converter is critical to the performance of the crawler and
must be tested when and if crawler performance is in question. The torque converter stall
test will help to determine if the problem is engine or transmission clutch pack related.
Stall Test Procedures
Because the crawler will be operated at high idle and full load during this test make sure all
personnel in the work area are clear of the machine at all times. Walk completely around the
machine before starting, sound the horn and observe all safety rules.
1. Operate the unit until the transmission housing is at normal operating temperature.
DO NOT PEFROM this test with cold oil. Run the engine up to high idle and
record the engine speed for future reference.
IMPORTANT: Do not perform the stall test for more then 30 second or
excessive heat will be generated.
2. Use the service brake pedal to prevent the machine from moving. Run the engine
at high idle and engage the third speed forward. Record the engine speed that is
maintained.
REMEMBER: Let the unit run at high idle for two minutes between test to
prevent the torque converter from over heating.
3. Perform the same test as outlined in step #2 above for each speed forward and
reverse. The engine should maintain the same RPM as recorded in step #2.
4. Refer to specification to determine if the stall speeds are within correct ranges.
Results
If the engine speed does not drop as low in one speed as the rest, it would be an
indication that a clutch pack in the transmission is slipping.
See next page for troubleshooting guide
Wait a Minute…How do I do a hydraulic and total stall test, check the torque
converter pressure, torque converter pump flow and/or cooler flow? At this time the
procedure has not been determined, refer to the service manual in the future.
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TORQUE CONVERTER
TORQUE CONVERTER TESTING
Problem Possible Cause Corrective Action
High Converter 1. Oil cooler lines restricted 1. Clean, inspect or replace hyd.
Temperature lines or cooler.
2. Low oil level 2. Fill to proper level
3. Working crawler in improper 3. Select lower gear for working
gear conditions
4. Worn converter pump 4. Replace pump
5. Pump drawing air 5. Tighten loose fittings and
suction hose clamps.
6. Converter pressure relief set 6. Adjust converter relief valve.
low
Low Oil Pressure 1. Suction filter plugged 1. Clean / replace filter
2. Low oil level 2. Fill to proper level
3. Worn oil pump 3. Replace pump
4. Worn seal rings 4. Replace converter seal rings
5. Relief valve open 5. Clean & inspect and adjust
6. Shaft bushings worn relief valve
6. Replace shaft bushings
High Oil Pressure 1. Oil cooler lines restricted 1. Clean, inspect or replace hyd.
Lines or cooler
2. Improper oil 2. Drain and refill with correct oil
3. Cold oil 3. Converter operating
temperature reached,
pressure should normalize
4. Relief valve not working 4. Inspect relief valve and adjust
Lack Of Power 1. Engine not functioning 1. Perform stall test
properly
2. Air in oil 2. Converter pump suction lines
loose or porous
3. Oil level low 3. Fill to proper level
4. Improper oil 4. Drain & fill with correct oil
5. Worn seal rings 5. Replace converter seal rings
6. Relief valve set low 6. Clean, inspect and adjust
relief valve
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TORQUE CONVERTER
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