Title: Lubrication and Bearings
1Lubrication and Bearings
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2What is Friction
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- Friction - resistance to movement between two
objects - The amount of friction depends on the following
1. Material - 2. Surface finish
- 3. Amount of pressure holding the two
together 4. How fast they move
3What is Friction
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- friction generates heatRub your hands together
they get hot - dry friction - both parts clean and free of other
materials - wet friction - parts have another material placed
between them such as oil
4What is a Bearing
- A Bearing is a device used to support and guide a
rotating, Oscillating, or sliding shaft or wheel. - A bearing is designed to
- 1. Reduce friction
- 2. Support a load
- 3. Guide moving parts
5 Bearing construction
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- friction - sliding friction - two smooth surfaces
sliding against each other - half speed bearing - turbos
- anti friction - rolling friction - uses balls or
rollers or small needles between the moving parts
6 Bearing construction
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7Bearing construction
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8Bearing construction
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9Bearing construction
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10Bearing construction
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11Bearing construction
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12Bearing construction
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13Bearing Load
- If the wrong type of bearing is used it may not
be able to carry the load that is applied to it.
The load is dependent on both weight and
direction. - There are Three types of loads.
14Bearing Load (Radial)
- The load is at right angles to the shaft.
15Bearing Load (Thrust)
- The load is Parallel to the shaft
16Bearing Load (Angular)
- The load is a combination of Radial and Thrust.
17Bearing Failure
- Premature bearing failures are caused by
- 1. Fatigue (overloaded, under lubed)
- 2. Poor lubrication (wrong type, under lubed)
- 3. Contamination (dirt and water)
- 4. Installation with the wrong tool
(there is a correct tool for every job)
18Full- Floating
19Insert Bearings
- removable bearing split in two pieces for easy
installation and removal
20Insert Bearings
- steel back with soft lining, coating can be of
babbitt, copper-lead-tin or aluminum coating - locating tabs help keeps insert bearing from
turning
21Insert Bearings
- crush height the .001 to .002 protruding above
rod cap and rod that when bolted together forms
the tight fit that prevents the bearing from
turning.
22Insert Bearings
- An undersize bearing is used on a crankshaft that
has been machined to a smaller size.
23BEARING PERFORMANCE
- load strength- must withstand pounding from
compression and firing stroke - anti scuffing - if oil pressure is lost lining
must be soft enough to prevent crankshaft journal
from being scratched or scuffed
24BEARING PERFORMANCE
- corrosion - must resist corrosion from vapors and
acids in crankcase - conformation - must conform to shape of
crankshaft journal
25BEARING PERFORMANCE
- embedability - must allow small particles to
embed itself into bearing material so journal
won't be scratched - temperature - must work equally well both hot
and cold must transfer heat well - oil hole or groove for lubrication
26BEARINGS
- rod bearings, bearings in the connecting rod
- main bearings, bearings that go where the main
bearing cap hold the crankshaft in place.
27THRUST BEARINGS
- thrust bearing, has sides on to help prevent end
play of crankshaft, sometimes use a separate
piece for the side.
28THRUST BEARINGS
294 Jobs of Oil
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- Cleans - Cools - Seals -Lubricates -
30Bearing Clearance
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- Oil is pumped to the bearing and separates the
parts. It allows the parts to turn without
touching each other. When parts touch they will
be destroyed. - bearing clearance average about .002
31Bearing Clearance
32How to lubricate a engine
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- engines lubricated three ways for a 4-stroke
engine - Full pressure
- Splash
- Combination - splash and pressure- most common
in automotive applications
33Full pressure
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- bearings are oiled by pumping oil to the
bearings, sometimes the oil is dripped on or is
squirted on to parts
34Splash
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- use of dippers on connecting rods to splash oil
around (one cylinder engines) or dripping oil on
the engine parts
35Combination
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- both systems used- splash and pressure -
- other methodstwo cycles mix gas and oilcould
be premix or a oil injection system
36Oil galleries and lines
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- Oil gallery - oil supply line in engine
- oil is carried through the engine by these lines
- some rods are drilled full lengths some have
squirt holes
37Oil filters
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38Oil filters
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- most common materialspaper and cotton waste
- canister - old style
- spin on
39Filtering Systems
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- two types of filtering systems
- full flow, all oil is filtered before going to
bearings, filter has relief valve in case of
plugged filter - bypass filter, part of oil is being filter at all
times but not before it is going to the bearings
40Oil pumps
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- gear, rotary, vane and plunger
- most common automotive engine
- gear and rotary
41Gear
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- two gears mesh together forcing oil out
42Rotary
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- inner rotor and outer rotor 4 points fit inside 5
points
43Vane
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- used as pump in some automatic transmissions(this
one, a vane pump out of a air wrench)
44Plunger
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- used a lot in one cylinder engines
45Pick up tube and screen
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46Pressure Relief Valve
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- when oil pump develops too much pressure the
Pressure Relief valve will open and allows to
return to sump by changing spring tension
pressure can be raised or lowered
47Oil sludge
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- Black thick Goomixture of water oil dirt usually
formed in engines never reaching operating
temperature - thermostat taken out or to many
short tripsformation of a white sludge - caused
by, cold weather, short trips, too much water
48Varnish or lacquer
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- usually known as engine varnish is formed from an
engine running at hot temperature for extended
periods - the heat causes the oil to break down
and a varnish is created on valve covers and
other parts to avoid varnish deposits use good
clean oil and change regularly
Light brown coating is Varnish
49Additives in oil
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- detergent - prevent sludge and varnish deposits
- foam inhibitors - prevent oil from
foamingoxidation inhibitors - prevent oil
oxidation at high speed
50Additives in oil
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- corrosion rust inhibitors - helps prevent these
- anti wear additives - coat metal surfaces with a
strong slippery film moly graphite
51crankcase ventilation
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- draft tube
- positive crankcase ventilation
52open - draft tube
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- Older engines use a draft tube to vent the
crankcase. It is just a vent with a filter in
it. Uses a Breather cap to allow air in.
53PCV - positive crankcase
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- open - breather cap
- closedgoes from air cleaner to valve cover
54wet and dry sump systems
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55windage tray
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- Bolt to bottom of engine prevent oil from foaming
due to crankshaft rotation.
56Oil viscosity
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- thickness or fluidity of the oil, oil's ability
to resist flow - classified as a number such as 10,20,30,40
- multi grade or multi viscosity 5w-30, 10w-30
57service ratingsgo through handout
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- Go to this web site and read the classifications
- http//www.lubrizol.com/ReadyReference/6-OilClasse
s/Sclass.htm
58how often should oil be changed,filter?
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- 1,000 - 7,500 average
- About every 3,000 - 4,000 miles recommended
- depends on length of operation, temperature of
air and car. Condition of all filters - air, oil
gas -, PCV valve, driving conditions, paved
roads, and dust or dirt in the air.
59what kind of oil should I buy ???
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60What kind of filter should I buy????
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- Some companies spent a lot of money on
advertising and very little on filters, some just
build good filters. You choose, cut some apart
and look for yourself.
61The End
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