Cat 3512B Specifications
| Engine Model: Caterpillar 3512B |
| Engine Type: 4-cycle 12-cylinder direct injection liquid-cooled diesel |
| Total Displacement: 3160 cu.in (51.8 L) |
| Rated Engine Power: 1000-1800 Hp (746-1342 kW) at 1800 rpm |
| Aspiration Type: Turbocharged, aftercooled |
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The Caterpillar 3512B is a high-output,
heavy-duty, V-12 diesel engine designed for the most demanding
industrial, mining, marine, and power-generation applications. As part
of Caterpillar’s proven 3500-series engine family, the 3512B is
engineered for continuous operation under full load, delivering long
service life, exceptional torque, and excellent fuel efficiency relative
to its size and output. Operators rely on this engine for 24-hour duty
cycles in remote, high-stress environments such as mining haul trucks,
large industrial pumps, oil-and-gas equipment, drilling rigs, and marine
propulsion or auxiliary systems.
The 3512B’s performance is defined by a robust cast-iron block,
forged-steel crankshaft, high-capacity turbocharging, aftercooling,
modular cylinder heads, and an efficient mechanical or electronic fuel
system depending on configuration. These engines are commonly derated or
tuned for specific applications, allowing them to meet requirements
ranging from high-power intermittent loads to long-term continuous duty.
Known for reliability and rebuildability, the 3512B remains a popular
choice across industries requiring extreme durability and
high-horsepower diesel technology.
The Caterpillar 3512B is a four-stroke, water-cooled, turbocharged,
aftercooled V-12 diesel engine with a displacement of 51.8 liters (3,160
cubic inches). Bore diameter is 170 mm (6.69 inches), and stroke length
is 190 mm (7.48 inches). The V-angle between banks is 60 degrees.
Compression ratio varies by rating and configuration but is typically
around 13.5:1.
Output ratings depend heavily on
application:
– Industrial and petroleum versions: 1,200–1,800 horsepower (895–1,342
kW) at 1,800–2,100 rpm
– Marine propulsion versions: 1,200–1,650 horsepower (895–1,230 kW) at
1,600–1,800 rpm
– Generator-drive versions: 1,000–1,500 horsepower (746–1,120 kW) at
1,200–1,800 rpm
Peak torque varies widely with calibration but generally falls between:
5,500 and 7,500 Nm (4,057–5,530 lb-ft) at 1,200–1,600 rpm. Idle speed is
usually set between 600 and 650 rpm. Governed maximum speed depends on
application, typically 1,600–2,100 rpm. Firing order is
1-12-5-8-3-10-6-7-2-11-4-9.
The crankshaft is forged steel, fully counterweighted, and supported by
seven large-diameter main bearings. Pistons are forged-aluminum alloy
with steel struts for high-temperature and high-load operation. Piston
rings include two compression rings and one oil-control ring. The
connecting rods are forged steel with replaceable inserts. The
camshafts—one for each cylinder bank—are gear-driven for precise
long-term timing control.
The cylinder block is cast iron with deep ribbing and massive frame
strength to withstand extreme cylinder pressures and continuous heavy
duty cycles. It features a two-bank V configuration with individual
cylinder bores arranged in pairs. Coolant passages surround each
cylinder to maintain even thermal distribution, essential for preventing
distortion over long operating cycles. The block incorporates heavy
main-bearing caps and a stiff crankcase bedplate to support large
rotating masses at sustained high load.
The 3512B uses individual cylinder heads, one per cylinder, each cast
from high-strength iron. This modular design simplifies service
procedures and allows individual cylinders to be repaired without
disturbing the entire bank. Heads feature direct-injection combustion
chambers. Each cylinder has four valves—two intake and two
exhaust—actuated by rocker arms driven from the gear-driven camshaft.
Valve seats are hardened for extreme thermal load resistance.
Typical valve lash (cold):
– Intake: 0.38–0.43 mm (0.015–0.017 in)
– Exhaust: 0.64–0.69 mm (0.025–0.027 in).
The fuel system depends on configuration:
– Early 3512B engines: mechanically actuated unit injectors
– Later configurations: electronically controlled unit injectors (MEUI)
or full electronic control (ADEM)
Fuel is drawn through primary and secondary filters by a gear-type fuel
transfer pump. High-pressure injection is achieved at the injector body,
with injection pressures exceeding 1,400 bar in electronically
controlled systems. Fuel timing and metering in electronic versions are
controlled by the ADEM ECM.
Fuel system maintenance:
– Replace fuel filters every 250 hours or as specified
– Inspect injectors every 1,500–2,000 hours
– Check injection timing (mechanical versions) at major service
– Drain water separator routinely.
The lubrication system is a full-pressure, high-capacity wet-sump or
optional dry-sump configuration depending on installation. A gear-driven
oil pump circulates large volumes of oil through full-flow and bypass
filters. Lubrication targets include crankshaft main bearings, rod
bearings, camshafts, rocker assemblies, turbochargers, and accessory
drives. Oil capacity varies with arrangement but generally ranges from:
300 to 400 liters (79–106 US gallons).
Normal oil pressure:
– 345–550 kPa (50–80 psi) at rated speed
– 140–275 kPa (20–40 psi) at idle
Recommended oil: SAE 15W-40 or 30-weight high-performance diesel oil
meeting Caterpillar specifications. Oil change intervals typically range
from 250 to 500 hours depending on duty cycle.
The cooling system uses a high-flow, gear-driven centrifugal water pump
circulating coolant through block, heads, and aftercoolers. Cooling
capacity depends on model and radiator configuration but typically
ranges from: 250 to 350 liters (66–92 US gallons).
The thermostat begins opening at approximately 82°C (180°F) and fully
opens near 95°C (203°F). Many 3512B installations use jacket-water
aftercooling (JWAC) or separate-circuit aftercooling (SCAC) systems for
optimal intake-air temperature control.
| Intake and Exhaust Systems |
The intake system includes heavy-duty air filtration—dry-element,
dual-stage, or oil-bath depending on environment. Turbochargers compress
intake air, which is then cooled by aftercoolers to improve density and
reduce combustion temperature. Exhaust manifolds are high-temperature
cast iron, feeding one or two turbochargers depending on model.
Marine versions may use water-cooled exhaust systems. Industrial
versions may require spark arrestors or mufflers depending on
regulations.
| Electrical and Starting Systems |
Electrical configurations vary:
– Most engines operate on 24-volt systems
– Alternator output commonly ranges 35–70 amperes
Electronic engines use the ADEM control
module for:
– Injection timing and duration
– Monitoring sensors (coolant, boost, oil pressure, temperature, speed)
– Protection functions (overspeed, overheat, low oil pressure).
Depending on application, the 3512B may
support:
– Hydraulic pump drives
– Air compressors
– Power-take-off (PTO) systems
– Remote cooling systems
– Generator heads (genset configurations)
– Marine gearboxes.
Approximate physical dimensions:
– Length: 2,400–2,800 mm (94.5–110.2 in)
– Width: 1,600–1,900 mm (63.0–74.8 in)
– Height: 1,900–2,200 mm (74.8–86.6 in)
Dry weight varies significantly by packaging: 4,800–6,000 kg
(10,580–13,230 lbs).
– Engine oil and filter: every 250–500 hours
– Fuel filters: every 250 hours
– Air filters: inspect every 100 hours; replace as needed
– Coolant: replace every 2 years
– Valve lash: adjust every 1,000 hours
– Injector service: every 1,500–2,000 hours
– Compression testing: every 4,000 hours
– Turbocharger inspection: every 2,000 hours.
– Cylinder head bolts: 610–680 Nm (450–500 lb-ft)
– Main bearing caps: 740–880 Nm (546–649 lb-ft)
– Connecting-rod bolts: 270–310 Nm (199–229 lb-ft)
– Flywheel bolts: 700–750 Nm (516–553 lb-ft)
– Crankshaft pulley bolt: 900–1,000 Nm (664–738 lb-ft)
– Oil drain plug: 70–90 Nm (52–66 lb-ft)
– Injector hold-downs: 40–50 Nm (30–37 lb-ft).
The Caterpillar 3512B is widely used in:
– Mining haul trucks (large rigid-frame trucks)
– Oil-and-gas drilling rigs
– Industrial pump systems
– Power-generation gensets
– Marine propulsion and auxiliary engines
– Construction and heavy-industrial machinery
– Large compressors and hydraulic drives.
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