As the parts rotate, the oil is carried directly to the surfaces to be The dip feed system is often used with other lubrication systems such as the gravity feed system just described...
Trang 1b Gravity feed lubrication systen
The gravity feed lubrication system is
primarily used in transfer cases and
nosebox assemblies This system
usually has a pump to transfer the oil
from the reservoir to an area above the
components to be lubricated Nature
takes over at that point through
gravity which distributes the oil (fig
3-7) Rotating components also pick up
oil and splash it throughout the
assembly
lubricated
Fig 3-8 Dip feed
system
Fig 3-7 Gravity feed system
c Dip feed system The dip feed system is used in most axle and differential assemblies In the dip feed lubrication system (fig 3-8), the components are partially submerged in oil As the parts rotate, the oil is carried directly to the surfaces to be
The dip feed system is often used with other lubrication systems such as the gravity feed system just described
Trang 2a Splash feed system The splash
feed lubrication system was once used
extensively in automotive engines The
connecting rods in engines using this
lubrication system are equipped with
dippers on their ends As the rods
rotate through the crankcase, the
dippers pick up oil and splash it
upward, lubricating the rest of the
components (fig 3-9) This system
works much like the dip feed system
The splash feed system is still used in
combination with other systems on large
engines and is also used on smaller
engines as the main source of
lubrication
Let's have some more fun Unscramble
the words to find the components that
use the listed lubrication systems
If you know the answers, this should
be easy
t
1
4 4
4 ⁄
⁄ ⁄
⁄
⁄
⁄
4
⁄
777 777772///////272
Fig 3-9 Splash feed
° Full force feed system -_ticmaotua misanstrnois
e Splash feed system - lsilma neengsi
e Gravity feed system - anerfsrt sesac
e Dip feed system - enfdifalitre
How did you do? If you couldn't figure them out, you can find the correct answers on the next page
Trang 33104 Components of the Engine Lubrication System
To properly service, troubleshoot, or repair the components of a lubrication system, you must know the components that make up the system and understand how they operate Remember, your engine's life depends on the lubrication system Let's begin at the
bottom of the engine and work our way up
a Oil pan and sump The oil pan
1S normally made of thin sheet
metal or cast aluminum It bolts
to the bottom of the engine block
and holds the oil for the
lubrication system (fig 3-10)
Most engines have a magnetic drain
plug located in the sump (lowest
point) of the pan Using this kind
of plug helps reduce wear by
removing any metal shavings from
the oil Baffles keep the oil Fig 3-10 Oil pan and sump from splashing around in the pan
-b Oil] pumps The oil pump is the
heart of the lubrication system
It pulls the oil from the sump and
delivers it under pressure through
the engine oil filter and galleries
to the engine components and
bearings
There are several types of oil
pumps but the two most commonly
used are the gear type and rotor
Fig 3-11 Rotor and gear Oil pumps
The unscrambled words from the previous page are:
° Full force feed system -_automatic transmission
° Splash feed system -_small engines
e Gravity feed system -_ transfer case
e Dip feed system -~_ differential
Trang 4The rotor oil pump (fig 3-12)
has a set of star shaped
rotors inside its housing;
they work together to
pressurize the oil As the
oil pump drive shaft turns,
the inner rotor, which is
attached to the shaft, causes
the outer rotor to spin The
eccentric action of the two
rotors forms pockets that
A large pocket is formed on
the inlet side of the pump
filled pocket becomes smaller
as it nears the outlet Fig 3-12 Rotor oil pump
This squeezes the oil, forcing operation
it out of the pump and into
the oil galleries
The spinning action is repeated over and over to produce a
relatively smooth flow of oil
(fig 3-13) has a set of gears Z2
VE
p>
SEAL FORMED system pressure
Oil on the inlet side of the
pump is caught between the
gear teeth and carried around
the inside wall of the pump
meshing of the gear teeth
oil galleries | DRIVE GEAR SEAL FORMED
Fig 3-13 Gear pump operation
Trang 5Most oil pumps are mounted on the engine so that they can be gear driven from the crankshaft or camshaft They may also be mounted externally or internally An example of an external pump is
shown in figure 3-14 This pump is used in the M939 series
vehicle engines and is driven directly off the engine camshaft The drive gear turns the oil pump shaft which powers the internal pump drive and idler gears An example of an internal pump is shown in figure 3-15; this is the dual gear type pump used in the LVS engine
FUME DRIVE
DRIVE
GEAR
®
0
2nd DRIVE AND IDLER
GEAR SHAFT SHAFT
Fig 3-14 Gear type oil pump
OIL PICKUP
UP TUBE CRANKSHAFT
h1 1g N09 ĐIẾt
0 [Ƒ
REMOVED
Fig 3-15 Internal dual gear oil pump (LVS)
Trang 6c Oil pickup tube and screen
line for the pump One end of the pickup is attached to the oil The oil pickup is the supply pump inlet while the other end extends into the oil sump
most cases, the pickup is attached to an oil screen
shows a good example of this arrangement
In
Figure 3-15 The pickup screen
prevents large dirt particles and other contaminants from
entering the pickup tube and oil pump
ad Oil pressure relief valve
Often called an oil pressure
regulator valve, the oil
pressure relief valve (fig 3-
16) is a spring-loaded valve
located in the oil pump, engine
block, or oil filter housing
This valve's job is to regulate
oil pressure Why is it
CLOSED
-—®r~
oP
parE te etal
RELIEF VALVE
NORMAL OIL
RELIEF VALVE
N -
Ki
TS
EXCESS OIL
needed? Oil pumps are designed PRESSURE PRESSURE
to pump a large amount of oil,
but when enough oil has been
limits are reached, the
pressure relief valve opens to
allow excess oil to return to
the sump
e Oil galleries
valve
Oil galleries are small passages cast or machined into the cylinder block and head (fig 3-17)
oil to flow to the engine bearings and other moving parts
They allow
Main oil galleries are the large passages through the center of the block They provide an oil passageway to the crankshaft
bearings, camshaft bearings, and lifters The main galleries connect to smaller passages that run up to the cylinder heads
Trang 7
SPLASH LUBRICATION
OIL PAN
SPLASH LUBRICATION
PICK-UP SCREEN
OIL FILTER | OIL PUMP
Fig 3-17 Oil galleries
f Oil filter The oil filter removes small particles of metal, carbon, rust, dirt, and other contaminants from the motor oil
By doing this it protects moving engine parts from abrasive wear The oil filter often has a filtering element made of paper or cotton; as the oil flows through the filter, the element traps contaminants
An 01il filter by-pass valve is commonly used to protect the
engine from oil starvation should the filter element become
Clogged The valve opens if excessive pressure is formed in the filter and allows unfiltered oil to flow to the engine
components, thus preventing major damage (fig 3-18) We don't really want unfiltered oil lubricating engine parts, but
unfiltered oil is a lot better than no oil at all!
Trang 8There are two basic types of oil filters: the spin-on type and the cartridge type
e The spin-on filter (fig 3-18) is self contained This means that the filter shell, element, and bypass valve are all contained in one neat little package This
filter is used one time and thrown away Spin-on type filters are used on equipment such as the HMMWV, CUCV,
e The cartridge type filter (fig 3-19) has a separate
element and housing To service this type filter, you remove the reusable housing, install a new element, and replace the housing The M800 and M939 series vehicles have this type filter
SEAL
BY PASS VALVE ELEMENT
Fig 3-18 Spin-on type oil Fig 3-19 Cartridge type oil
g Oil sending unit and gauge An alert operator (you!) can prevent an engine from being destroyed by lubrication system
failure The oil pressure gauge is designed to give you the
information you need and it gets that information from a sending unit located in an oil gallery The gauge and sending unit work together to provide an accurate reading of the oil pressure The sending unit is a pressure sensitive variable resistance unit What does that mean and how does it work? Well, after we look at the operation, you'll be able to answer these questions
3-16
Trang 9The oil applies pressure to a diaphragm within the sending unit (fig 3-20) As the oil pressure increases, the sending unit
Giaphragm deflects in proportion, causing a corresponding change
in the sending unit's resistance
LEFT COq, RIGHT COIL
IGNITION SLIDING @” ————— c h TERMINAL
( bs A zô LEVER —2——> : ` «—— SENDING PRESSURE
UNIT
GROUND
OIL PRESSURE
Fig 3-20 Oil pressure gauge and sending unit circuit
Low oil pressure deceases the sending unit's resistance, which in turn causes higher current flow from the battery through the left coil of the gauge, through wire 1, and on to the sending unit This current flow causes the magnetic field of the left coil of the gauge to be stronger than the magnetic field of the right coil, pulling the pointer to the left and giving a low oil
pressure gauge reading
High engine oil pressure increases the resistance in the sending unit which causes the current to flow from the battery, through the left gauge coil, and then through the right gauge coil to ground The resistance of the right coil is less than that of the sending unit, so the current, taking the path of least
resistance, deflects the pressure gauge needle to the right The gauge then indicates a high oil pressure reading
h Oil coolers Since we covered oil coolers in the previous study unit, they will not be covered in depth here You should remember that an oil cooler works somewhat like a radiator and uses the engine coolant or air flow to remove excess heat from the oil Doesn't this sound familiar? I sure hope so
Okay, you have just covered the engine lubricating system Let's see if you can list the components that make up that system To make this more interesting, try to do it without going back
through the lesson
Trang 10
The correct answers are:
) Oil sump and pan
) O11 pump
) O11 pickup tube and screen
) Oil pressure relief valve
)ạ O1l galleries
) Oil filter
) O11 sending unit and gauge
) Oil cooler
(1
(2
(3
(4
(5
(6
(7
(8
Now for your score: Eight out of eight classifies you as a
"pro," seven out of eight will give you the title "semi-pro," but Six out of eight or less means that you should go back and study the engine lubrication system more thoroughly!
3105 Automatic Transmission Lubrication System
Since the automatic transmission lubrication system works
Similarly to the engine lubrication system, we won't go into
great detail discussing its components Like the engine, it also has a full force-feed type lubrication system Oil operates and lubricates the transmission Figure 3-21 shows the components of the system (but not their actual locations)
VALVE BODY
VALVE
SCREEN
Fig 3-21 LVS automatic transmission lubrication system
Trang 11The lubrication pump in the automatic transmission not only
provides lubrication for all the moving parts but also provides the operating pressure for the valves, servos, and pistons that are used to control the transmission
The pump illustrated in figure 3-21 is a rotor type pump which is driven by the transmission's torque converter An oil pressure regulator limits the oil pressure to the amount the transmission needs for proper operation The oil filter on most automatic transmissions is located in the oil pan Some models use a
pickup tube while others have eliminated the tube by mounting the filter directly to the bottom of the valve body assembly The transmission on the LVS also uses a spin-on filter as a secondary filter
Most large truck automatic transmissions have transmission oil temperature gauges to warn operators of transmission overheating These large transmissions also use oil coolers to keep the oil temperature in the normal operating range
The lubricating oil used in automatic transmissions varies from one transmission to another So, before servicing a
transmission, you should refer to the vehicle lubrication order
It specifies the correct lubricant to use Lubrication orders will be covered later in this study unit
Answer the following question to see how well you're doing What component in the automatic transmission provides operating
pressure for servos, valves, and pistons? If you said the oil
Let's now take a look at the lubrication system for the manual transmission