The Kubota DH850-B is a 855 cc, (52.5 cu·in) natural aspirated three-cylinders four-stroke liquid-cooled internal combustion vertical diesel engine, manufactured by Kubota for general-purpose applications.
Cylinder bore and piston stroke are 72.0 mm (2.83 in) and 70.0 mm (2.76 in), respectively. Compression ratio rating is 22.0:1.
The DH850-B engine produced 21.4 PS (15.7 kW; 21.0 HP) at 3,600 rpm of net (intermittent) horsepower, 23.4 PS (17.2 kW; 23.0 HP) at 3,600 rpm of gross (intermittent) horsepower and 49.9 N·m (5.1 kg·m, 36.8 ft·lb) at 2,400 rpm of maximum torque.
The Kubota DH850-B features:
- Spherical type combustion chamber
- Bosch K-type mini fuel injection pump
- Bosch throttle type injection nozzle
- Centrifugal ball mechanical governor
- Forced lubrication by pump lubrication system
- Liquid cooling system
- Electric starter (12V, 0.8 kW)
General information
| Engine Specifications | |
| Engine model | DH850-B |
| Engine type | 4-stroke, vertical, three-cylinders |
| Displacement | 855 cm3, (52.2 cu·in) |
| Max. horsepower | Net (continuous): 17.8 PS (13.1 KW; 17.5 HP) at 3,600 rpm Net (intermittent): 21.4 PS (15.7 kW; 21.0 HP) at 3,600 rpm Gross (intermittent): 23.4 PS (17.2 kW; 23.0 HP) at 3,600 rpm |
| Max. torque | 49.9 N·m (5.1 kg·m, 36.8 ft·lb) at 2,400 rpm |
| Cooling system | Liquid-cooled |
| Lubricating system | Forced lubrication by pump |
| Combustion chamber | Spherical type |
| Fuel injection pump | Bosch K Type Mini Pump |
| Injection type | Indirect injection |
| Injection nozzle | Bosch throttle type |
| Firing order | 1-2-3 |
| Fuel used | Diesel fuel No.2-D |
| Starting system | Electric starter (12V, 0.8 kW) |
| Starting support device | Glow plug in combustion chamber |
| Governor | Centrifugal ball mechanical governor |
| PTO shaft rotation | Counterclockwise (from PTO shaft side) |
| Dimensions (L x W X H) | 471 x 423 x 566 mm (18.5 x 16.7 x 22.3 in) |
| Dry weight | 82.6 kg (182.1 lbs) |
Cylinder Block and Head
| Cylinder block | |
| Compression ratio: | 22.0:1 |
| Cylinder bore: | 72.0 mm (2.83 in) |
| Piston stroke: | 70.0 mm (2.76 in) |
| Cylinder internal diameter (standard): | 72.000-72.019 mm (2.8346-2.8354 in) |
| Number of piston rings (compression / oil): | 2/1 |
| Connecting rod small end diameter (standard): | 20.000-20.013 mm (0.7874-0.7879 in) |
| Piston pin diameter: | 20.002-20.011 mm (0.7875-0.7878 in) |
| Side clearance (Second): | 0.085-0.112 mm (0.0033-0.0044 in) |
| Side clearance (Oil): | 0.020-0.055 mm (0.0008-0.0022 in) |
| Ring end gap (Top): | 0.250-0.400 mm (0.0098-0.0157 in) |
| Ring end gap (Second): | 0.250-0.400 mm (0.0098-0.0157 in) |
| Ring end gap (Oil): | 0.250-0.400 mm (0.0098-0.0157 in) |
| Ring width (Second): | 1.458-1.470 mm (0.0574-0.0579 in) |
| Ring width (Oil): | 3.975-3.990 mm (0.1565-0.1571 in) |
| Number of main bearings: | 4 |
| Crankshaft main journal diameter: | 43.934-43.950 mm (1.7297-1.7303 in) |
| Crankpin journal diameter: | 36.959-36.975 mm (1.4551-1.4557 in) |
| Cylinder head | |
| Valves: | 2,(6 valves in total) |
| Valve timing (INTAKE): | Open: 20° Before T.D.C. Close: 45° After B.D.C. |
| Valve timing (EXHAUST): | Open: 50° Before B.D.C. Close: 15° After T.D.C. |
| Valve seat width (INTAKE): | 2.120 mm (0.0835 in) |
| Valve seat width (EXHAUST): | 2.120 mm (0.0835 in) |
| Value seat angle (INTAKE): | 45° |
| Value seat angle (EXHAUST): | 45° |
| Valveface angle (INTAKE): | 45.5° |
| Valveface angle (EXHAUST): | 45.5° |
| Valve steam diameter (INTAKE): | 6.960-6.975 mm (0.274-0.2746 in) |
| Valve steam diameter (EXHAUST): | 6.960-6.975 mm (0.274-0.2746 in) |
| Valve spring free length (INTAKE): | 35.100-34.800 mm (1.3819-1.3701 in) |
| Valve spring free length (EXHAUST): | 35.100-34.800 mm (1.3819-1.3701 in) |
| Camshaft lobe height (INTAKE): | 26.880 mm (1.0583 in) |
| Camshaft lobe height (EXHAUST): | 26.880 mm (1.0583 in) |
| Camshaft journal diameter : | 32.934-32.950 mm (1.2966-1.2972 in) |
Tightening torque
| Tightening torque specs | |
| Head cover cap nuts (M7x1.0): | 6.9-8.8 Nm (0.7-0.9 kgf-m, 5.1-6.5 lb-ft) |
| Head screws and nuts (M9x1.25): | 64.7-69.6 Nm (6.6-7.1 kgf-m, 47.7-51.4 lb-ft) |
| Main bearing case screw 1 (M7x1.0): | Flange bolts 26.5-30.4 Nm (2.7-3.1 kgf-m, 19.5-22.4 lb-ft) Non-flange bolt 19.6-23.5 Nm (2.0-2.4 kgf-m, 14.5-17.4 lb-ft) |
| Main bearing case screw 2 (M8x1.25): | 29.4-34.3 Nm (3.0-3.5 kgf-m, 21.7-25.3 lb-ft) |
| Flywheel screw (M10x1.25): | Flange bolts 58.8-63.7 Nm (6.0-6.5 kgf-m, 43.4-47.0 lb-ft) Non-flange bolt 53.9-58.8 Nm (5.5-6.0 kgf-m, 39.8-43.4 lb-ft) |
| Connecting rod screw (M7x0.75): | 26.5-30.4 Nm (2.7-3.1 kgf-m, 19.5-22.4 lb-ft) |
| Rocker arm bracket nuts (M7x1.0): | 16.7-20.6 Nm (1.7-2.1 kgf-m, 12.3-5.2 lb-ft) |
| Idle gear shaft screws (M6x1.0): | 9.8-11.3 Nm (1.00-1.15 kgf-m, 7.2-8.3 lb-ft) |
| Idle gear shaft screws (M6x1.0): | 9.8-11.3 Nm (1.00-1.15 kgf-m, 7.2-8.3 lb-ft) |
| Glow plugs (M10x1.25): | 19.6-24.5 Nm (2.0-2.5 kgf-m, 14.5-18.1 lb-ft) |
| Drain plug (M11x1.25): | 39.2-49.0 Nm (4.0-5.0 kgf-m, 28.9-36.2 lb-ft) |
| Nozzle holder assembly (M24x2.0): | 29.4-49.0 Nm (3.0-5.0 kgf-m, 21.7-36.2 lb-ft) |
| Nozzle holder and nozzle retaining nut: | 58.8-78.5 Nm (6.0-8.0 kgf-m, 43.4-57.9 lb-ft) |
| Nozzle holder mounting screw (M24x2.0): | 39.2-49.0 Nm (4.0-5.0 kgf-m, 28.9-36.2 lb-ft) |
| Crankshaft nut (M24x1.5): | 137.3-156.9 Nm (14.0-16.0 kgf-m, 101.3-115.7 lb-ft) |
Service Data
| Engine | |
| Maximum speed: | 3,780 rpm |
| Idle speed: | 800 rpm |
| Cylinder compression: | 31.5 kgf/cm2 (3.09 MPa, 448 psi) |
| Compression differential limit between cylinders: | 10% or less |
| Valve clearance | |
| Intake valve clearance: | 0.145-0.185 mm (0.0057-0.0073 in) |
| Exhaust valve clearance: | 0.145-0.185 mm (0.0057-0.0073 in) |
| Oil system | |
| Lubrication system: | Forced lubrication by pump |
| Oil type: | API CC or better |
| Oil capacity: | 3.7 L (3.91 US. qt, 3.26 Imp. qt.) |
| Oil filter: | Full flow paper filter (cartridge type) |
| Oil pressure: | At idle spped: 68 kPa (0.7 kgf/cm2, 10 psi) At rated speed: 196-441 kPa (2.0-4.5 kgf/cm2, 29-64 psi) |
| Fuel system | |
| Fuel injection pump | Bosch K Type Mini Pump |
| Injection nozzle | Bosch throttle Type |
| Injection timing: | 20° B.T.D.C. |
| Fuel injection pressure | 13.73-14.71 MPa (140-150 kgf/cm2, 1991-2133 psi) |
| Cooling system | |
| Type: | Pressurized radiator, forced circulation with water pump (not included in the basic engine) |
| Thermostat’s valve opening temperature: | 80.5-83.5°C (176.9-182.3°F) |
| Temperature at which thermostat completely opens: | 95°C (203°F) |
| Coolant capacity | 4.6 L (4.9 US. qt, 4.0 Imp. qt.) |
| Electrical system | |
| Battery: | 12V, 65AH or equivalent |
| Starter mica undercut: | 0.5-0.8 mm (0.0197-0.0315 in) |
| Starter brush length: | 16.0 mm (0.6299 in) |
| Alternator (no-load voltage): | AC 20V |
| Glow plug resistance: | 1.0-1.2 Ω |
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