Cat 3056 Specifications
| Engine Model: Caterpillar 3056 |
| Engine Type: 4-cycle inline 6-cylinder turbocharged liquid-cooled diesel |
| Total Displacement: 365 cu.in (6.0 L) |
| Rated Engine Power: 173 Hp (129 kW) at 2200 rpm |
| Fuel System Type: Direct fuel injection |
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The Caterpillar 3056 is a versatile inline
six-cylinder, 6.0-liter diesel engine, engineered for reliability in
demanding mobile and stationary applications. A direct descendant of the
3000 family, it builds upon the proven 3054 architecture with two
additional cylinders, providing greater power density and smoother
operation. The engine is characterized by its mechanical fuel system,
robust construction with wet cylinder liners, and gear-driven camshaft.
Configurations span from naturally aspirated to turbocharged and
turbocharged air-to-air aftercooled models, accommodating a broad power
spectrum. This adaptability makes the 3056 suitable for a wide range of
roles, from auxiliary marine power and generator sets to industrial
machinery. Its design prioritizes durability, straightforward
maintenance, and extended service intervals.
Engine Type: Inline 6-Cylinder, Four-Stroke Cycle Diesel.
Aspiration: Naturally Aspirated (NA), Turbocharged (T), or Turbocharged
Air-to-Air Aftercooled (ATAAC).
Displacement: 6.0 Liters (365 cubic inches).
Bore: 105 mm (4.13 inches).
Stroke: 127 mm (5.00 inches).
Engine Power: 173 HP (129 kW).
Operating Speed: 2200 RPM.
Compression Ratio: Ranges from 15.5:1 to 17.0:1, dependent on aspiration
and application.
Firing Order: 1-5-3-6-2-4.
Rotation (Viewed from Flywheel End): Counterclockwise.
Governor Type: Mechanical, all-speed or variable speed,
application-specific.
Emission Certification: Early configurations are mechanically governed,
pre-Tier. Later iterations meet Tier 2/Stage II standards through
optimized combustion.
The engine block is a heavy-duty, single-piece cast iron construction,
providing a rigid foundation for the six-cylinder layout. It
incorporates replaceable wet-type cylinder liners. The liner flange is
precision-machined and seated at the top of the block with a sealing
gasket.
The block design includes extensive internal ribbing for strength and
integral coolant passages surrounding each liner. Main bearing caps are
made of nodular iron, each secured by two vertical bolts. The camshaft
rotates within bearings machined directly into the block material. This
design ensures alignment and minimizes distortion under high loads.
The engine uses a single cast iron cylinder head covering all six
cylinders. The design employs two valves per cylinder - one intake and
one exhaust. Hardened valve seat inserts provide wear resistance for
extended life. Valve guides are pressed into the head and are
replaceable.
Valve actuation is via pushrods and rocker arms; the rocker arm shaft is
mounted on the cylinder head. Valve lash is adjusted manually using a
screw and locknut on each rocker arm. The head gasket is a multi-layer
steel or composite design, depending on the specific model and its power
rating.
The fuel system is a direct injection, mechanically controlled design.
It employs individual camshaft-driven injection pumps, one for each
cylinder. These element-type pumps generate high pressure and deliver
fuel to multi-hole pencil injectors mounted in the cylinder head.
Injection timing is fixed and set during engine assembly.
A gear-type transfer pump supplies fuel from the tank to the injection
pumps. The fuel circuit includes a primary filter/water separator and a
secondary spin-on fuel filter. This system is recognized for its
simplicity, durability, and precise mechanical control of fuel delivery.
Lubrication is provided by a gear-type oil pump driven from the
crankshaft gear train. Oil is drawn from the sump through a pickup tube
and screen, then pressurized through a full-flow, spin-on oil filter. A
bypass valve protects the system if the filter becomes blocked.
Filtered oil is routed through a plate-type oil cooler before
distribution via the main oil gallery. From the gallery, oil feeds the
crankshaft main and connecting rod bearings, the camshaft bearings, and
the valve gear through hollow pushrods. Piston cooling jets spray oil
onto the underside of each piston for additional cooling.
Coolant circulation is managed by a centrifugal water pump, gear-driven
from the front of the engine. Coolant flows from the pump through
passages in the cylinder block and cylinder head. Engine temperature is
regulated by a wax-pellet thermostat.
Turbocharged air-to-air aftercooled (ATAAC) models use a separate
air-to-air heat exchanger, mounted in the intake circuit, to lower the
temperature of the turbocharged intake air. The engine cooling system
requires connection to a radiator or heat exchanger of adequate capacity
for the specific application's heat rejection.
Starting System: 12-volt or 24-volt electric starting motor with an
integrated solenoid. Charging System: A brushless alternator, with
output amperage (e.g., 65A, 85A) selected based on the electrical load
requirements of the application. Air Intake System: A dry-type air
cleaner, either panel or cylindrical, with a service indicator.
Turbocharged models route compressed air through the aftercooler core
before entering the intake manifold. Exhaust System: A dry, cast iron
exhaust manifold routes combustion gases to the turbocharger (if
equipped) or directly to the exhaust pipe.
Dimensions vary significantly between a bare industrial engine and a
fully dressed marine auxiliary or generator set. The core industrial
engine length is approximately 1050 mm, width is 640 mm, and height is
850 mm (41.3 in x 25.2 in x 33.5 in). Complete marine auxiliary or
generator set packages, including flywheel housing, alternator, and base
frame, are substantially larger and heavier. The net dry weight of an
industrial 3056 engine, without fluids or driven accessories, is
approximately 505 kg (1113 pounds). Complete marine generator set
weights are documented in the range of 1185 to 1192 kg (2612 to 2628
pounds).
Engine Oil Grade: Use Caterpillar Diesel Engine Oil (DEO) or an
equivalent oil meeting API CH-4/SJ or higher classifications. SAE 15W-40
is specified for general use across a wide ambient temperature range.
Oil Change Interval: Determined by service conditions and hours of
operation. Standard intervals range from 250 to 500 hours. Severe-duty
cycles necessitate more frequent changes. Oil System Capacity:
Approximately 15.0 Liters (4.0 US gallons) for the engine lubrication
system, including a filter change.
Cooling System Capacity: The engine-only coolant capacity is
approximately 15.0 Liters (4.0 US gallons). The total capacity of the
installed system is greater and depends on the radiator, piping, and any
heat exchangers.
Fuel Filter: Replace the secondary fuel filter cartridge every 500 hours
or according to the equipment service schedule. Air Filter: Service or
replace the element based on the restriction gauge reading. Operation in
high-dust environments requires increased inspection frequency.
Valve Lash Adjustment (Cold): Intake: 0.20 mm (0.008 in). Exhaust: 0.45
mm (0.018 in). Adjust at initial break-in (50 hours) and every 3000
hours thereafter.
Engine Coolant: Use a 50/50 mixture of ethylene glycol antifreeze and
deionized or distilled water. Maintain correct levels of supplemental
coolant additive (SCA) to prevent liner pitting and corrosion.
Cylinder Head Bolts: Tighten in a specific sequence to 90 Nm (66 lb-ft).
Then, tighten again in sequence to 130 Nm (96 lb-ft). Finally, tighten
each bolt an additional 90 degrees of rotation. Main Bearing Cap Bolts:
Tighten to 140 Nm (103 lb-ft). Connecting Rod Cap Bolts: Tighten to 90
Nm (66 lb-ft), then tighten an additional 60 degrees. Flywheel
Housing-to-Block Bolts: Tighten to 75 Nm (55 lb-ft).
Flywheel-to-Crankshaft Bolts: Tighten to 115 Nm (85 lb-ft). Injector
Clamp Bolt: Tighten to 35 Nm (26 lb-ft). Oil Pan Bolts: Tighten to 27 Nm
(20 lb-ft). Oil Filter Cartridge: Install by hand until the gasket
contacts the base, then tighten an additional three-quarters of a turn.
Fuel Injection Pump Mounting Nuts: Tighten to 24 Nm (18 lb-ft).
The Caterpillar 3056 engine is applied in a
diverse array of equipment:
Marine: Serves as a propulsion engine for small workboats and as a
generator set (genset) engine for auxiliary shipboard power. Power
Generation: A common prime mover for generator sets in the 50-125 kVA
range, used for standby, prime, and continuous power.
Industrial: Found in hydraulic power units, large industrial air
compressors, pumps, and welding machines. Construction/Mobile: Used in
certain mid-sized excavators, wheel loaders, and as a power source for
mobile screening/crushing plants. Oil and Gas: Employed in drilling mud
pumps and other auxiliary equipment within the sector.
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