C7.1 Industrial Engine Introduction Caterpillar


The following model views show a typical C7.1 engine. Due to individual applications, your engine may appear different from the illustrations.

Illustration 1g02150184
Typical example
(1) Rear lifting eye
(2) NOx Reduction System (NRS)
(3) Front lifting eye
(4) Alternator
(5) Refrigerant compressor
(6) High-pressure turbocharger
(7) Low-pressure turbocharger
(8) Engine oil drain
(9) Flywheel housing
(10) Flywheel
(11) Exhaust gas cooler (NRS)

Illustration 2g02150185
Typical example
(12) Crankcase breather
(13) Electronic control module (ECM)
(14) Starting motor
(15) Oil filter
(16) Oil gauge
(17) Oil filler
(18) Primary fuel filter
(19) Secondary fuel filter
(20) In-line fuel strainer
(21) Electric fuel priming pump

The location of the in-line fuel strainer (20) and the priming pump (21) will depend on the application.

Illustration 3g02150187
Typical example
(22) Outlet connection to the air to air charge cooler
(23) Connection for the air inlet
(24) Outlet connection for the coolant
(25) Housing for the water temperature regulator
(26) Water pump
(27) Inlet connection for the Coolant
(28) Vibration damper
(29) Belt tensioner
(30) Belt

The C7.1 diesel engine is electronically controlled. The C7.1 engine has an Electronic Control Module (ECM) that receives signals from the fuel injection pump and other sensors in order to control the electronic unit injector. The fuel injection pump supplies fuel to the high-pressure manifold (Rail). The high-pressure manifold (rail) distributes fuel to the electronic unit injectors.

The six cylinders are arranged in-line. The cylinder head assembly has two inlet valves and two exhaust valves for each cylinder. The ports for the exhaust valves are on the right side of the cylinder head. The ports for the inlet valves are on the left side of the cylinder head. Each valve has a single valve spring.

Each cylinder has a piston cooling jet that is installed in the cylinder block. The piston cooling jet sprays engine oil onto the inner surface of the piston in order to cool the piston. The pistons have a Quiescent combustion chamber in the top of the piston in order to achieve clean exhaust emissions. The piston pin is off-center in order to reduce the noise level.

The pistons have two compression rings and an oil control ring. The groove for the top ring has a hard metal insert in order to reduce wear of the groove. The skirt has a layer of graphite in order to reduce the risk of seizure when the engine is new. The correct piston height is important in order to ensure that the piston does not contact the cylinder head. The correct piston height also ensures the efficient combustion of fuel which is necessary in order to conform to requirements for emissions.

The crankshaft has seven main bearing journals. End play is controlled by thrust washers which are located on both sides of the number 6 main bearing.

The timing case is made of aluminum or cast iron. The timing gears are stamped with timing marks in order to ensure the correct assembly of the gears. When the number 1 piston is at the top center position of the compression stroke, the marked teeth on the idler gear will align with the marks that are on the fuel injection pump gear, the camshaft gear, and the gear on the crankshaft. There are no timing marks on the rear face of the timing case.

The crankshaft gear turns the idler gear which then turns the following gears:

  • the camshaft gear

  • the accessory drive gear (if equipped)

  • the fuel injection pump gear

  • the water pump gear

The camshaft runs at half the rpm of the crankshaft. The fuel injection pump runs at the same rpm as the crankshaft.

The fuel injection pump that is installed on the left side of the engine is gear-driven from the timing case. The fuel is transferred to the fuel injection pump by an external electric transfer pump. The electric transfer pump draws fuel across a suction strainer that supplies fuel to the primary fuel filter and the secondary fuel filter. The fuel then travels to the fuel injection pump. A pressure regulator that is installed in the low-pressure fuel system controls the fuel pressure to the fuel injection pump. The pressure regulator regulates the fuel at an absolute pressure of 150 kPa (22 psi) when the engine is at idle speed.

The fuel injection pump increases the fuel to a maximum pressure of 200 MPa (29000 psi). The fuel injection pump delivers the fuel to the high-pressure manifold (Rail). The fuel injection pump is not serviceable. The engine uses speed sensors and the Electronic Control Module to control the engine speed.

For the specifications of the C7.1 engine, refer to the Specifications, "Engine Design".

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