Yanmar TF120 Specifications
| Engine Model: Yanmar TF120 |
| Engine Type: 4-stroke 1-cylinder horizontal water-cooled diesel |
| Total Displacement: 38.9 cu.in (0.64 L) |
| Rated Engine Power: 11.8 Hp (8.8 kW) at 2400 rpm |
| Fuel System Type: Direct injection |
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The Yanmar TF120 is a horizontal,
single-cylinder, water-cooled 4-stroke diesel engine, renowned for its
heavy-duty durability and operational efficiency. As part of Yanmar’s TF
series, this powerplant was engineered to deliver reliable mechanical
power for agricultural tillers, industrial pumps, and small-scale
electricity generation. The engine features Yanmar’s signature direct
injection system, which provides superior fuel atomization compared to
older indirect injection (IDI) designs. This results in lower fuel
consumption, reduced exhaust emissions, and easier cold starting in
demanding environments.
The Yanmar TF120 is available in several configurations to suit
different operating conditions. The TF120H variant utilizes a hopper
tank for coolant water, while the TF120M (or TF120R) variant is equipped
with a pressurized radiator for more consistent temperature control. An
electric start option is indicated by the ‘E’ suffix. A sophisticated
two-shaft balancer system is integrated into the crankcase,
significantly reducing the vibration characteristic of single-cylinder
engines and improving operator comfort during extended use.
The engine operates on a four-stroke diesel cycle utilizing direct
injection. It is configured for horizontal operation, typically driving
a flywheel mounted PTO (Power Take-Off). Engine speed is regulated by a
mechanical centrifugal governor.
Engine Type: Horizontal single-cylinder, water-cooled, 4-stroke diesel
Displacement: 0.638 liters (638 cc / 38.9 cu.in)
Bore x Stroke: 92.0 mm x 96.0 mm (3.62 in x 3.78 in)
Compression Ratio: 17.7:1
Combustion System: Direct Injection
Firing Order: Single cylinder (N/A)
Idle Speed: Variable dependent on governor setting (typically 800 -
1,000 rpm)
Maximum Output (Intermittent): 8.8 kW (11.8 hp) @ 2,400 rpm
Maximum Output (Continuous): 7.7 kW (10.3 hp) @ 2,400 rpm
Maximum Torque: 46.1 Nm (34.0 lb-ft) @ 1,600 rpm
Rotation Direction: Counter-clockwise (when viewed from flywheel side)
The cylinder block and crankcase are constructed as a single high-grade
cast iron unit, providing the rigidity necessary to withstand high
compression forces and thermal stress. The design incorporates the
mounting provisions for the two-shaft balancer system.
Cylinder Bore Diameter: 92.0 mm (3.62 in)
Piston Material: High-temperature aluminum alloy
Crankshaft: Forged carbon steel, dynamically balanced
Connecting Rod: Forged steel
Balancer System: Two-shaft (twin-shaft) balancer driven by the
crankshaft
Cylinder Block Construction: Cast iron monoblock (integral crankcase)
The cylinder head is manufactured from cast iron, featuring a vertical
valve arrangement (OHV) actuated by pushrods. The direct injection
system places the fuel injector centrally in the cylinder head,
directing the spray into a re-entrant type combustion bowl machined
directly into the piston crown.
Valvetrain: OHV (Overhead Valve), gear-driven camshaft located in the
crankcase. 2 valves total (1 intake, 1 exhaust). Valve Seat Material:
Heat-resistant alloy steel. Camshaft Drive: Helical gear train.
Valve Clearance (Cold, Mechanical
Adjustment):
Intake: 0.15 mm (0.006 in)
Exhaust: 0.20 mm (0.008 in)
The fuel system utilizes a direct injection configuration with a
Bosch-type in-line injection pump. The mechanical pump delivers
high-pressure fuel to a throttling pintle-type injector. Fuel injection
timing is set to 17 deg before top dead center (BTDC).
Fuel Injector: Throttling pintle type nozzle
Injection Pump: Bosch-type individual plunger pump
Injection Pressure: 19.6 MPa (200 kgf/cm2 / 2,843 psi)
Fuel Injection Timing: 17° BTDC (stationary)
Fuel Filter: Cartridge type with sediment bowl
Fuel Tank Capacity: 11.0 - 11.9 liters (2.9 - 3.1 US gal)
Fuel Requirement: Diesel fuel (Light oil), minimum cetane rating of 45
The lubrication system is a fully pressurized wet-sump design utilizing
a trochoid pump integrated into the engine casing. The pump draws oil
from the sump and forces it through a full-flow paper element filter
before distributing it to the crankshaft, camshaft, and balancer shafts.
Oil Pump Type: Trochoid pump
Recommended Oil Viscosity: SAE 30 (Summer) or 10W-30/15W-40
(Multi-grade)
Oil Capacity (Total/Effective): 2.8 liters / 1.0 liter (3.0 qt / 1.1 qt)
Oil Pressure (at rated speed): 200 - 400 kPa (29 - 58 psi)
Oil Filter Type: Spin-on full-flow cartridge
Oil Pan Material: Integrated cast iron (wet sump)
The cooling system is a pressurized, liquid-cooled design. Two primary
variants exist: Radiator type (TF120M/R) which uses a centrifugal pump
to circulate coolant through a matrix, and Hopper type (TF120H) which
relies on thermo-siphon circulation.
Coolant Type: Clean fresh water with antifreeze and corrosion inhibitor
(Radiator type)
Coolant Capacity (Radiator type): 2.3 liters (2.4 qt)
Water Pump Type: Centrifugal (Radiator type only)
Thermostat: Wax pellet type, opening temperature 71°C (160°F)
Starting System: Manual hand-cranking with a ratcheting handle
(Standard). Electric start is available on the TF120E variant, utilizing
a 12V starter motor and a 95E41R series battery.
Governor: Mechanical centrifugal ball-weight type, integrated into the
injection pump for all-speed regulation.
Air Cleaner: Dry paper element type with cyclone pre-cleaner.
Overall Length: 747 - 784 mm (29.4 - 30.9 in)
Overall Width: 362 - 377 mm (14.3 - 14.8 in)
Overall Height: 530 - 545 mm (20.9 - 21.5 in)
Dry Weight (Radiator type): 108 - 116 kg (238 - 256 lbs)
Dry Weight (Hopper type): 102 kg (225 lbs)
Valve Clearance: Inspection/adjustment every 500 hours (Cold).
Fuel Injection Timing: Check every 1,000 hours (17° BTDC).
Engine Oil Change: Every 100 hours (severe service) or 200 hours
(standard).
Oil Filter Replacement: Every 200 hours or every second oil change.
Fuel Filter Cleaning: Every 200 hours.
Coolant Change: Every 2,000 hours or 2 years (antifreeze recommended for
Radiator type).
Air Cleaner Element: Clean every 50 hours (dusty conditions); replace
annually.
Balancer System: lubricated by engine oil.
Cylinder Head Nuts: 65 - 70 Nm (48 - 52 lb-ft)
Connecting Rod Cap Nuts: 35 - 40 Nm (26 - 30 lb-ft)
Main Bearing Cap Bolts: 55 - 60 Nm (41 - 44 lb-ft)
Flywheel Nuts: 120 - 130 Nm (89 - 96 lb-ft)
Injector Nozzle Holder: 68 - 72 Nm (50 - 53 lb-ft)
Rocker Arm Shaft Bolts: 20 - 22 Nm (15 - 16 lb-ft)
Oil Drain Plug: 30 - 35 Nm (22 - 26 lb-ft)
Crankshaft Pulley Nut (PTO side): 100 - 110 Nm (74 - 81 lb-ft)
The Yanmar TF120 engine is utilized primarily in agricultural and
industrial machinery requiring durable, low-speed torque. It is the
standard power unit for specific models of rotary tillers (power
tillers/Hand tractors), stationary irrigation pumps, and small-scale
generator sets (7.7 kVa standby).
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