b 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
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
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
type (fig 3-11)
Fig 3-11 Rotor and gear Oil pumps
The unscrambled words from the previous page are:
° Full force feed system -_automatic transmission
Trang 4
The 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
change in size
A large pocket is formed on the inlet side of the pump
As the rotor turns, the oil-
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
The gear type oil pump PUMP HOUSING
(fig 3-13) has a set of gears Z2
that produce 1ubrication IDLER GEAR FES LS VE p> INTERNAL 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
housing The rotation and LOW OUTLET
meshing of the gear teeth
create a seal to pressurize IN GEAR
the oil and force it through TEETH
the pump outlet and into the INTERNAL
oil galleries | DRIVE GEAR SEAL FORMED
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
IDLER GEAR SHAFT
GEAR SHAFT SHAFT
Fig 3-14 Gear type oil pump OIL PICKUP OIL PUMP y SCREENS DRIVE = GEAR OIL PICK UP TUBE CRANKSHAFT h1 1g N09 ĐIẾt 0 [Ƒ
đ ) _ : / 0 ` “Ni! OIL PUMP ENGINE BLOCK
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
pumped and the usable pressure Fig 3-16 Oil pressure relief
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
Trang 7SPLASH LUBRICATION OIL PAN SPLASH LUBRICATION PICK-UP SCREEN OIL FILTER | OIL PUMP BYPASS VALVE
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
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,
and LVS |
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 HOUSING BY PASS VALVE ELEMENT Fig 3-18 Spin-on type oil Fig 3-19 Cartridge type oil filter filter
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
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
SWITCH WIRE 2 CONTACT Or on
( bs A zô LEVER —2——> : ` «—— SENDING PRESSURE UNIT GROUND | BATTERY SPRING OIL PRESSURE AND + 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
Trang 10The 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
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
pump, you're absolutely correct |
Trang 123106 Manual Transmission Lubrication System
The manual transmission uses a combination of the splash and dip feed methods of lubrication It doesn't have an oil pan or sump; the housing contains the lubricant The oil is filled to and maintained at a level (fig 3-22) that ensures the adequate
lubrication of all moving parts
The lubricant is also the primary source of cooling for the manual transmission As the lubricant splashes over the gears and bearings, it picks up heat Once again, the oil volume must be properly maintained to ensure adequate cooling
Trang 133107 Transfer Case Lubrication System
Most large transfer cases, such as those used in the LVS and the M939 series vehicles (figures 3-23 and 3-24), use a pump to
transfer the oil from the bottom of the transfer case to the top Nature then takes over to allow the force of gravity to deliver the lubricant to all moving parts LUBRICATION PUMP ) LUBRICATION
Fig 3-23 LVS transfer case Fig 3-24 M939 series lubrication pump transfer case lubrication
pump
Now think back Do you remember which type of lubrication system this is?
Trang 14Lubrication oil is the primary means of cooling for most transfer cases The HMMWV transfer, however, is cooled a little
differently It has an internal oil cooler which uses
transmission oil to help remove the heat from the transfer case (fig 3-25) TRANSFER CASE OIL COOLER ENGINE OIL COOLER TRANSMISSION OIL COOLER TRANSFER 4 CASE T v s
Fig 3-25 HMMWV transfer case internal cooler
As shown in figure 3-25, transmission oil leaves the
transmission, flows through the transmission oil cooler, the transfer case internal oil cooler, and then returns to the transmission There is no direct contact between the transfer case oil and the transmission oil
So, you could say that the transmission oil cooler assists in
cooling the
Trang 15Now, could a loss of transmission oil, without obvious external leaks, be an indicator of a damaged transfer case oil cooler? You bet it could How would you know? Well, there's a very easy way that you could see if this has happened: check both the
transmission and transfer oil levels the transmission oil level would be low and the transfer case would be overfull
3108 Axle and Differential Lubrication System
Axles and differentials are normally lubricated by the dip feed method The axle assembly housing is the reservoir for the
lubricant Some large vehicles, such as the LVS, have axle
assemblies that use an inter-axle differential These axles have a lubrication pump to transfer lubricant from the bottom of the axle housing to the top of the inter-axle differential Gravity then delivers the oil to all moving parts
The LVS also has a nose box assembly to transfer power Mounted on the number one axle, it has its own lubrication system which is separated from the axle assembly by two seals on an input
shaft The nose box center gear drives an oil pump, but the pump supplies lubricant for the differential, not the nose box itself There is no outside means of cooling for axle assembles Since
internal lubricants perform this function, a heavy gear oil is used Most axle housings also use magnetic drain plugs to attract and hold any metal particles
As with other components, always refer to the lubrication order before servicing or checking axle assemblies Keep a close eye on small components such as the axle shift units Since they hold very little lubricant, any sign of wetness indicates a possible problen
Lesson Summary In this lesson you identified the functions of lubricants and types of lubrication systems You determined the types of oil and grease to use in different climatic conditions, and described the operation of lubrication system components As stated earlier, oil is the life blood of any mechanical systen Just as your body will cease to function without blood,
Trang 16Exercise: Complete items 1 through 16 by performing the action required Check your responses against those listed at the end of this study unit
What are the four functions of lubricants? d Would you use a low or a high viscosity oil during summer Climatic conditions?
Would you use a 10 weight or a 50 weight oil during winter climatic conditions?
What type of oil is used during both winter and summer Climatic conditions?
There are two basic greases used for motor
transport equipment; they are GAA and GGP The temperature range of limits its use to temperatures above 0°F The chemical makeup of these two lubricants prevent them from being used
Matching: For items 6 through 10, match each component in column 1 to its primary lubrication system listed in column 2 Place your responses in the spaces provided Selections listed in column 2 may be used more than once
Column 1 Column 2
Component Lubrication System
6 Engine a Dip feed
7 Automatic transmission b Full force feed 8 Manual transmission c Gravity feed 9 Transfer case dad Pump feed
10 Axles e Splash/dip feed
Trang 17Matching: For items 11 through 16, match each component listed in column 1 to its function in column 2 Place your responses in the spaces provided Column 1 Component 11 12 13 14 15 16 Oil pump | Oil pressure relief valve Oil filter Oil sending unit and gauge Transmission oil pump “ HMMWV transmission 011 cooler Column 2 Function Delivers lubricant under pressure |
Removes large particles Holds oil supply for the lubrication system
Provides operating pressure for valves, servos, and pistons Provides accurate reading of oil pressure Removes small particles from the oil
Limits maximum oil pressure Provides a passage for the oil to travel
Trang 18Lesson 2 LUBRICATION ORDER LEARNING OBJECTIVE
1 Given a situation involving vehicle lubrication and a lubrication order, use the lubrication order to determine the required lubricants for selected components
2 Given a lubrication order and a list of terms/symbols, extract the meaning of the terms/symbols from the
lubrication order
3201 Purpose of the Lubrication Order
AS an organizational mechanic, you will normally not be able to specialize on any one vehicle or system You will be required to perform maintenance on all equipment The lubrication (lube) order provides you with a single consolidated source of
instructions Like a map, it lays out everything that you need to know to properly service and lubricate the equipment
The lubrication order (LO) is made of laminated material which will not be damaged if grease or oil is spilled on it
3202 Content of the Lubrication Order
The lubrication order has four parts Let's look at each one a Cover/instructional page The cover page (fig 3-26) begins with the lubrication order number and the date of publication This is followed by the nomenclature (Name/Model/NSN) of the vehicle or series of vehicles that the order covers On most lube orders, you will find descriptions of terms, symbols, and codes that are used throughout the order As a good example, look at the cover page in figure 3-26 Notice that the first three paragraphs provide information on service intervals All of this information is very important and most of it will be covered more thoroughly in this lesson There are terms
mentioned in the first paragraph that you may not be familiar with Let's define then:
© Hard time is the established time interval at which the particular service is to be performed
© On-condition means that the service is performed as required to maintain the equipment in an operational condition
© The Army Oil Analysis Program (AOAP) is a program
established to extend the service life of equipment by performing spectrometric analysis of used oil In other words, the oil is tested to determine if it needs to be changed and to identify contaminants This program will be covered in another lesson