Thursday, October 30, 2008

CAT Engine Course (Part 5) Lubrication System

The engine oil pressure has a normal operating range from 345 to 480 kPa (50 to 70 psi) and will be approximately 450 kPa (65 psi) at full load rpm. Flow of oil through the engine at rated rpm is approximately 340 litres/min (90 gpm).

In this diagram of the lubrication system, we see the oil reservoir (sump in the oil pan), the oil pump (1) with a pressure relief valve (2); the oil cooler (3) with a bypass valve (2); the oil line from the cooler to the oil filter base/housing (4); with bypass valve (2) [one bypass valve for each filter]. The oil goes from the oil filters through the oil line to the oil elbow (manifold) on the left top front of the block.

The oil pump takes oil from the sump and sends it through the oil cooler, oil filters, and into the oil elbow (manifold).

Oil is sent to the turbochargers through outside lines (9) that are connected to the elbow on the left from (if turbocharger is top mounted). Turbocharger drain lines empty into the camshaft compartments through the camshaft side covers (10).
In the elbow (manifold), the oil is divided; one branch is sent to a camshaft oil gallery (7) below the camshaft and fuel control shaft, the other branch to a main oil gallery (5) which is above the main bearings of the crankshaft and on the centerline of
the block.

The main oil gallery (5) sends oil through vertically drilled passages to each main bearing, then through the crankshaft to each connecting rod bearing.

The oil that flows to the rear of the main oil gallery is sent up to the rear top of the block into an adapter (elbow manifold). The adapter sends the oil again into a camshaft oil gallery (7) in the block to the passage below the right camshaft.
The adapter also has plugs that may be removed to supply oil when the turbochargers are mounted on the rear of the engine.

The inset on the right of the diagram shows the oil passages on the right side of the engine. The oil in camshaft oil gallery (7) on the left side and the right side below the camshafts sends oil to the camshaft journals (11). The oil goes through hollow dowels to the cylinder heads through passages to the three lifters (two lifters for
valves, one for the injector) and the rocker arm shaft (12).

Oil is sent from each end of the main oil gallery (5) through small passages to the sequence valves (6). The two sequence valves control oil flow into piston cooling jet manifolds. There is one sequence valve on the left front of the block for the left passage and one on the right rear of the block for the right passage.

The purpose of the valves is to stop oil flow into the piston cooling jet manifold until oil in passage (5) has more than 140 kPa (20 psi) pressure. During engine start-up, the sequence valves decrease the time needed for the oil pressure to come up in the
main oil gallery to the main and connecting rod bearings. The sequence valves also hold the oil pressure up during engine idling, especially when the oil is hot, and parts are worn.

When the oil pressure is more than 140 kPa (20 psi), the sequence valves open and let oil go to the lower small passages (8) alongside of the crankcase. This oil is sent to the piston cooling jets (one for each piston). Each cooling jet has two openings. As oil is forced through each opening, one stream (spray) of oil is sent to a passage in the bottom of the piston which takes the oil to a circular manifold inside the piston and cools the piston. The other stream of oil hits the piston underside to cool it
and give lubrication to the piston pin and bearing.

The inset on the right of the diagram shows the oil passage to the gear train. Oil is sent to the front and rear gear trains from the oil passages below the camshafts (7) through passages drilled in the front and rear housings and the front and rear
block face.

The oil pump (1) and pressure relief valve (2) can be seen here.

The oil pressure relief valve is in the oil pump body and keeps the oil at the correct pressure. It opens at above normal pressures and sends the extra oil back to the pump inlet. Oil pressure must be measured when the engine is at normal temperature of operation. Also, oil pressure must be measured at a location (tap) AFTER the oil
has gone through the oil cooler and filters. Oil pressure can be measured on each side of the block at the oil gallery plug.

Here we can see the:
1. oil cooler
2. oil line from the oil pump to the oil cooler
3. oil line to the filter base housing on the left side of the engine
The oil cooler (1) is on the right side of the engine and is a tube core-type. Coolant goes through tubes in the cooler, and oil goes around the outside of the tubes. The oil cooler supply line (2) is on the outside of the cooler. The oil flows through the supply line through the cooler to the oil line to the filter base housing (3). On the vehicle arrangement, the oil line goes under the oil pan to the filter base housing on the left side of the engine.

The oil cooler bypass valve is in the oil cooler housing. The oil cooler bypass valve permits oil to go around the cooler when the oil is cold and thick or when there is a restriction in the cooler. The bypass valve will open when there is a pressure
difference of 160 to 200 kPa (23 to 29 psi) across the oil cooler (from the inlet of the cooler to the outlet of the cooler).

This is the oil line (arrow) from the oil cooler to the filter base housing which goes under the oil pan. Also we can see the oil pan is held to the bottom of the block with bolts. The bolts go through the block and are turned into threaded holes in the pan. To improve service on some arrangements, the bolts go through the oil pan to the block.

On the left side of the engine, we see the three oil filters. The oil goes from the filter base housing to the manifold (elbow) on the front left top of the block. The oil flow
from the oil cooler goes through the line on the right into the filter base/housing and to the oil filters. (The oil filters shown are full-flow type spin-on filters.)

Each oil filter has a bypass valve behind the plates (see arrows). When the oil filters have a restriction, the bypass valve opens and sends the flow directly to the
oil line on the left which sends the oil to the block.
Each oil filter bypass valve will open when there is a pressure difference of 180 to 200 kPa (26 to 32 psi) across the filter (from the inlet side of the filter to the outlet side of the filter).

NOTE: Other applications of this engine can have the oil
filters at other locations.

Use a strap wrench , if needed, to remove the oil filters.

Change the oil filters when you change the engine oil at the service interval given in the Operation Guide.
Before installing the oil filters, be sure the old gasket is removed and the filter base is clean.
To install the oil filter, put clean oil on the gasket and turn the filter on the filter base until it contacts the base. Turn the filter 3/4 of one turn (270 degrees) more.

Put more oil in the engine when the oil level is at the ADD oil mark on the gauge.
Change the oil in the engine as recommended in the Lubrication and Maintenance Guide.
Vehicle engine dipsticks will be marked on both sides.
Be sure to read the correct side. The other side will read ADD, HOT-RUNNING.

The small lines going from the front, left oil manifold (elbow), sends oil to the turbochargers when they are top mounted. The large line from the bottom of the turbocharger is the oil drain which returns the oil to the camshaft compartment and

On the right rear of the engine block is the adapter (elbow manifold). Oil is sent from the main oil passage (gallery) to the top of the block. The adapter sends the oil into the camshaft bearing oil gallery. When the turbochargers are rear mounted, such as a Generator Set, Marine Engine, or Marine Auxiliary Engine, oil for the turbochargers comes from the two large plugs in the adapter.

Other engines (Industrial, Generator Sets, Marine and Marine Auxiliary Engine arrangements) have the oil filter housing (2) mounted across the front of
the engine.
Here we can see the:
1. drain valve
2. filter housing
3. bypass valve; and
The filter housing(2) has three (3) filter elements. The filter housing has a single bypass valve (3). On vehicular engines, there is one bypass valve for each filter. The oil inlet line goes from the oil cooler to the filter housing. The oil outlet line goes
from the oil filter housing to the oil manifold (elbow) on the block. Clean oil from the filters goes into the block in the same location as the vehicle engines.

The filter elements should be changed when the engine oil is changed. To install new filter elements,
open the drain valve (1) and drain the oil from the filter housing. Then remove the cap from the end (right-hand side) of the filter housing.
Remove the three filter elements and clean the filter housing with a clean lint-free shop towel.
Install new filter elements, a new seal, if needed.
Put the cap on the filter housing. After the engine is started, check the cap and seal for leaks.
A duplex oil filter is shown here.

Here we can see the crankcase dipstick on this industrial/generator set engine. There are either right-hand or left-hand locations for the dipstick
on the different engine arrangements.

Be sure there is oil in the sump before starting the engine. Then check the oil level with the engine idling and with the oil hot. The oil must be checked daily or every ten service meter units.
The oil must be between the “ADD” and “FULL” marks on the oil level dipstick.
Read More

Thursday, October 9, 2008

CAT Engine Course(Part 4) Cooling System

Cooling System

This diagram shows the basic cooling system. We can use it to see the components of the system and see how they are connected. In the diagram, we see the engine block, cylinder heads (separate heads for each cylinder), coolant manifold, housing of the temperature regulators (thermostats), water outlets bypass line from regulator housing to water pump, water pump, water inlet from radiator or heat exchanger, coolant line to the aftercooler, and the oil cooler.
1. water pump
2. oil cooler
3. cylinder heads
4. water manifold (right side)
5. aftercooler
6. temperature regulator housing
7. bypass line from regulator housing to water pump.

Coolant flow comes from the elbow which is connected to the radiator or other heat exchanger into the center of the water pump. The cooler flow is divided at the outlet of the water pump. One partflows to the aftercooler; the other part to the oil cooler.
Coolant sent to the aftercooler goes through the aftercooler and is sent by an elbow into a passage in the block near the center of the vee at the rear of the block. The coolant sent to the oil cooler goes through the oil cooler and flows into the water jacket of the block at the right rear cylinder. The coolant mixes and goes to both
sides of the block through distribution manifolds connected to the water jack of all the cylinders.
The main distribution manifold is located just above the main bearing oil gallery.

The coolant flows up through the water jackets and around the cylinder liners from the bottom to the top. Near the top of the cylinder liners, where the temperature is the hottest, the water jacket is made smaller. This shelf (smaller area) causes the coolant to flow faster for better liner cooling. Coolant from the top of the liners goes into the cylinder head which sends the coolant around the parts where the temperature is the hottest. Coolant then goes to the top of the cylinder head and out through an elbow, one at each cylinder head, into a manifold, one for each back of cylinders. Coolant goes through the manifold to the thermostat housing.

The water pump is gear driven at 1-1/3 times engine speed for the 1300 to 1800 rpm high speed engine and 2 times engine speed for the 1300 rpm low speed engines.

Coolant comes from the aftercooler and goes into this
elbow and into the engine block.

After the coolant goes through the oil cooler, it is sent into the engine block at the right rear cylinder. Coolant from the oil cooler and aftercooler mix (comes together) in the block and goes through the cylinder heads to the left and right water manifolds in the “vee” of the engine.

The bypass line goes from the temperature regulator housing to the inlet of the water pump. The regulators in the housing control coolant flow to the radiator or heat exchanger to regulate the temperature in the cooling system. When the coolant temperature is not high enough to open the regulators, the coolant will flow through the bypass line (bypassing the radiator) to circulate through the engine for quick warm-ups.

Four temperature regulators are in the thermostat housing.The housing has an upper and lower section. The sensing bulbs of the four temperature regulators are in the coolant in the lower section of the housing. Before the regulators open (upper inset), cold coolant is sent through the bypass line to the inlet of the water pump. As the temperature of the coolant increases to 88°C (180°F) and the regulators start to open (lower inset), coolant flow in the bypass line is stopped and coolant is sent through the outlets to the radiator or heatexchanger.
Coolant capacity is given in the Operation Guide for the engine only. Total system capacity will depend on the size of the radiator or heat exchanger. To prevent the coolant from freezing, it should have a mixture of 50 percent pure water, 50 percent
permanent antifreeze and a 3 to 6 percent concentration of corrosion inhibitor.

Here we see the housing for the temperature regulators (thermostats) and the four sleeve-type temperature regulators. The housing of the temperature regulator is above the front gear cover and supported by a compartment connected to the right and left water manifolds that are located above the cylinder heads.
Each of the regulators is positioned in a counterbore and has a lip-type seal.

Here the temperature regulator and seal have been removed from the housing. The smaller barrel portion of the regulator is the part that comes in contact with the seal.

When the regulator is closed (engine cold) coolant goes through the regulators. The coolant returns to the inlet of the water pump by way of the bypass
pipe (which is fastened to the opening in the front of the housing)
and does not get to the radiator.
When the regulator is open (engine hot) coolant goes through the
regulator out the side of the housingand then to the radiator for
cooling. On marine applications, the position of the regulator housing
will be upside down from the position in the photo.

The seals can be removed and replaced. To replace the seals, a seal driver must be used. To replace a seal, remove the old seal and clean the counterbore. Now install the seal in the housing with the lip of the seal away from the regulator.

Use a 1P529 Handle and a 1P489 Drive Plate to drive the seal into position in the housing.
When regulators and seals are replaced, the machinedsurfaces of the housing and cover must becleaned and a new gasket installed.

On the right, we can see the coolant outlet line and the coolant inlet line at the bottom. The outlet line and inlet line are connected to a radiator outside the building.

The bypass line goes from the top of the thermostat housing to the inlet side of the water pump. We can also see the fuel filter housing and oil filter
housing on this generator set arrangement.
Read More

CAT Engine Course (Part 3)Air Induction System

Clean each crankcase breather element every 1000
service hours or oil change. Wash the breather
with clean solvent or clean diesel fuel.

Air Induction system

In this diagram of the air induction and exhaust system, we seethe turbochargers (two), the air inlet system piping, theaftercooler, the air inlet plenum and elbows, the inletport and intake valves, the combustion chamber, the exhaust valves and the exhaust manifolds.
The location of the air inlet system, exhaust manifolds, turbochargers, piping, aftercooler and air plenum are all in the center of the vee of the block.

Intake air comes through the air cleaners (not shown) and into the compressor inlet of each turbocharger.

Velocity of the air is increased by the turbocharger compressor impeller. The air is sent through the piping into the aftercooler inlet where it has increased in pressure and temperature.

The air then goes down through the aftercooler into the plenum chamber in the center of the vee. The air is cooled by jacket water in theaftercooler.
The decrease in temperature of the air can
range from 38º to 93ºC or 100º to 200ºF.

From the plenum chamber, the air goes throughpassages along the sides of the aftercooler, through aluminum elbows into the inlet ports, inlet valves and into the combustion chambers.
After the combustion or power stroke, the exhaust gases go out through the exhaust
valves, exhaust manifold, through theturbocharger turbine and goes out into the
outside air.

This arrangement of the 3512 Engine has two turbochargers and an aftercooler.

The location of the turbochargers and aftercooler on the vehicle arrangement is in the vee of the banks of cylinders.

The two turbochargers send air into the aftercooler air inlet.

The air inlet system, exhaust manifolds, turbochargers, piping, and aftercooler are all located in the center of the vee.
From left to right are the:
1. coolant manifold (left)
2. exhaust manifold (left)
3. aftercooler
4. rear lifting bail (eye)
5. exhaust manifold (right); and the
6. coolant manifold (right)

Watercooled manifolds and turbochargers are available on marine engines and are available as attachments on the industrial and generator sets.
On 3500 Engine Arrangements with water cooled exhaust manifolds, the coolant manifolds will be (combined with) the exhaust manifolds.

Here we see a generator set arrangement.
The air filter housing and turbochargers are on the rear of the engine. We can also see the:
1. emergency shutoff system
2. premium instrument panel; and the
3. air starting system with filters

This is the rear of the engine. On the industrial generator set engines, the turbochargers are mounted on the rear of the engine.

Here we see the electrical connections for the solenoid of the emergency air shutoff valve.

A sensor in the control panel activates the emergency shutoff system when the engine overspeeds (engine rpm goes higher than the maximum rpm setting).

Other sensors activate the fuel shutoff solenoid and STOP engine operation, when conditions of low oil pressure and high coolant temperature exist.
The remote shutoff also activates the fuel shutoff solenoid to STOP engine.

This is the air inlet reset control of the emergency airshutoff. This is one style. There is another style.

With the pointer in the vertical up position, it is set to RUN. When the solenoid is activated, thevalve goes down closing off the inlet air, and the pointer goes to the STOP position.

This must be RESET (set again) to RUN manually before the
engine is started again and after the problem has
been corrected.
Read More

CAT Engine Course (Part 2)

Crankcase explosion relief valves, seen here, are normally attachments but are required on marine engines. They are available for industrial and generator set arrangements. These valves relieve the pressure of an explosion in the crankcase. An
explosion is possible when combustible gases start to burn because of heat or sparks. A common cause of ignition is heat from a failed bearing. Explosion relief valves open to release the pressure of an explosion - then close to prevent a second cycle of combustion. Basically they stop oxygen from getting in, which would permit further combustion.

This is the idler pulley used on some arrangements to tighten or loosen the belts. To tighten the fan (drive) belts, loosen the bolts that hold the bracket of the idler pulley. Move the idler pulley out until the tension of the belt is correct and tighten the bolts.
Install new belts if they show signs of too much wear. Belts come in sets. If one belt is bad, install a new set of belts. If only one new belt is installed, the new belt will carry the load and all belts will fail rapidly.

Some engine arrangements have a bracket with a bolt or a hydraulic cylinder with a grease fitting to tighten the belts. Either
(1) loosen the nut on the adjustment bolt and turn it until the belt tension is correct, then tighten the bolt. Or,
(2) put grease into the fitting with a grease gun until the tension on the belts is correct. After the fan belts are tightened correctly, check the
tension of the alternator belts.

The alternator is located on the right front side and has
two drive belts which must be adjusted

To check the tension of the alternator drive belts, push
down in the belts half way between the center of
the pulleys. If the tension is not correct, tighten
the belts.

To make an adjustment to the alternator belts, loosen
the outside nut on the support bracket bolt
several turns. Turn the inside nut until the belt
tension is correct. Then tighten the nut on the
adjustment bolt that holds the bracket.

Two governors will be available on the 3500 Engines.
The Caterpillar 3161 shown will be standard on the Vehicle, Industrial and Marine engines. The Generator Set and Marine Auxiliary will use the Woodward 2301 Governor.
The standard location for the governor or actuator is on the right front timing gear housing. As as option, the 3161 Governor may be located on the left side of
the front housing. The actuator for the 2301 Governor is available only on the right-hand side.

The 3161 Governor is driven by a 2400 rpm gear.
The speed is reduced to 1370 rpm through a bevel
gear set in the governor drive.
The governor has a hydraulic unit inside which has its own oil supply.
The 3161 Governor has a boost-activated smoke limiter.
A manual shutdown liver is provided on the engine.
An electric solenoid or hydraulic cylinder operated
shutdown is also available.
The electric solenoid operated shutdown is used on Vehicle, industrial
and Marine arrangements.
The hydraulic operated shutdown is used with hydramechanical
shutoff or at customer request.

For some applications such as generator sets and marine
auxiliary engines, a Woodward electric governor and
actuator are used.
Here we can see:
1. governor actuator (EG-10P)
2. control rod from actuator to fuel control shaft
3. shaft (control) lever
4. governor drive housing
5. control cable to 2301 governor

The crankcase breather group is normally on the front
left side of the engine. When it is necessary to
locate the governor on the left side, the breather
group location is on the front right side.
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