Reliable and proven engine technology
John Deere 6R Series Tractors feature the reliable and proven PowerTech PVX/PSX engines. These air-to-air aspirated engines deliver constant power over a wide range of engine revolutions per minute (rpm) with a power bulge above rated power to provide excellent torque in demanding applications.
- Engines deliver a constant power range of 30 percent with a power bulge of 10 percent.
- High-pressure common rail (HPCR) fuel injection system and other key engine parts work together to sense engine load and then instantly respond as needed to pull through tough soil conditions.
- Engine rpm fluctuations are reduced to minimize the need to downshift the transmission.
- Fewer shifts results in less ground speed variations, providing higher overall tractor productivity.
To match the engine power characteristics and improve economy of operation, the rated engine speed is 2100 rpm.
The full frame concept
Engine integrated in full frame
The engine is an integrated part of the full frame concept. The engine is connected to the frame using vibration-absorbing isolators. Further vibration reduction is achieved by utilizing a heavy-duty torsional damper in the Cardan shaft, coupling the flywheel to the clutch housing.
- Eliminates engine block stress, because the engine is no longer a structural part of the tractor.
- Reduces noise and vibration transfer to other tractor components.
Engines feature a heavy-duty, high-quality gray iron block. The one-piece block design features generous internal webbing to provide sturdy engine structure. The block is further strengthened by circular truss ribs that serve as lower supports for wet cylinder liners.
To ensure a long vehicle life, engine cylinders are wet sleeve liners. In the event a repair is needed in long-term operation, the engine can easily be reconditioned to updated specifications.
The coolant manifold is full length for equal cooling capabilities across all cylinders.
The PowerTech PVX 4.5L and 6.8L and PowerTech PSX engines feature directed cooling around the top of the cylinder liners.
Top liner cooling lowers temperatures at the top of the cylinder for durability of the piston and piston rings. This also allows the piston rings to be farther up on the piston, decreasing the amount of dead air in the combustion process, increasing efficiency, and lowering emissions.
The block rib design minimizes engine noise by stabilizing the cylinder liners.
Piston and rings
All PowerTech PVX and PSX 4.5L and 6.8L engines use aluminum pistons for high strength and resistance to wear. The large-diameter piston bowl with high-dome design works with the four-valve head to provide greater airflow with less restriction both in and out of the combustion chamber. This greatly improves economy and lowers exhaust emission levels.
Cooled, filtered oil is constantly sprayed on the underside of each piston. The low-friction piston design incorporates an integral directed oil galley, taking full advantage of the oil spray jet to improve piston and ring cooling, extending life.
The oil spray jet provides excellent underside piston dome cooling, as well as lubrication of the piston pin and pin bushing and cylinder wall lubrication. Oil spray nozzles are positioned on support ribs over main bearings to supply cooled and filtered oil to the pistons.
Connecting rods and piston pins
Piston pin features:
- Full floating design utilizes all bearing surfaces of the pin for more even load distribution, even wear, and long life.
- Large diameter and thick walls ensure maximum rigidity.
- Highly polished and hardened surface of pin reduces wear.
- Slip fit and retained in pistons by snap rings.
Wrist pin lubrication comes from high-volume piston spray jet.
Wet sleeved, flanged cylinder liners are made of compact graphite iron for greater strength and stiffness.
Directed top-liner cooling reduces oil consumption and enhances combustion efficiency by reducing wear in the top ring turnaround area and improving piston ring performance.
A dynamically balanced crankshaft is constructed of heat-treated, high-carbon forged steel for maximum strength. Journal surfaces are induction hardened for long life.
A flanged-style thrust bearing is used for long life. Main crankshaft bearing caps are machined while fastened to the block to ensure precise crankshaft alignment.
The John Deere exclusive WEAR-GARD™ connecting rod bearing design increases lubricating oil film thickness in the bearing area, where high loads are present. This further improves durability and reliability.
The 6.8L engine uses a camshaft made from 1080 steel to provide the strength and durability required to operate four valves in each cylinder.
Six large camshaft bearing journal diameters are sized to handle the heavy-duty, four-valve head. Two additional camshaft bearings provide added strength and reliability. The camshaft lobe profile design is complemented by the intake and exhaust valve shapes and sizes for power and efficiency.
The initial valve lash adjustment is 2000 hours, then every 2000 hours thereafter.
Four-valve cylinder head
Additional four-valve cylinder head benefits are as follows:
- Positions the injector in the center of the piston and combustion chamber for even piston loads and mixing of fuel
- Maintains cooler head temperatures through a high rate of airflow
- Raises the air-fuel ratio while reducing internal operating temperatures for improved reliability and fuel efficiency
- Valves and replaceable valve seat inserts designed to minimize flow restriction (engine uses special powdered metal valve guide inserts with impregnated lubricant for proper seating and to prolong wear)
- Offers excellent pull-through characteristics delivered by constant high torque
- Allows faster field operating speeds
There is improved lugging ability throughout the entire working range with significant productivity improvements at low engine rpm.
The intake manifold is located above the exhaust manifold.
- Location allows intake air to go directly down through the head with minimal turning to aid in engine breathing characteristics.
The engine width is not changed greatly, allowing for a narrow tractor hood and excellent row-crop visibility.
High-pressure common rail fuel injection system and engine control unit (ECU)
Every PowerTech PVX/PSX engine utilizes the high-pressure common rail (HPCR) fuel system to supply fuel to injectors. The high-pressure fuel pump instantly responds to requirements for more or less fuel flow or pressure. The pressure is generated by the gear-driven piston pump. This electronically controlled and high-pressure pump delivers pressure on demand according to the application requirements.
- High-pressure common rail delivering exactly the same fuel pressure level at all of the injectors
- High responsiveness under all load and speed conditions, which extends the engine working range to lower speeds, delivering more power and productivity in the field at outstanding fuel saving engine speeds
- Performance-matched fuel consumption delivering reduced fuel costs per acre
The ECU uses signal inputs from sensors and pre-programmed performance modeling to control critical engine functions such as:
- Fuel quantity
- Injection timing
- Air-to-fuel ratio
- Multiple fuel injections
- Amount of cooled exhaust gas recirculation (EGR)
- A host of other control parameters to deliver peak fuel economy and engine performance
Each injector is controlled individually by the ECU. The ECU turns the injector on and off during each firing cycle to control the fuel delivery into each cylinder. The ECU can sense engine speed and load changes at a rate of 100 times per second and respond instantly to them. Load and speed sensing allows each cylinder’s fuel delivery rate to be adjusted independently at the individual injector. With each injection cycle, the ECU can make the following adjustments on the go:
- Number of injections
- Fuel pressure in the common rail
- Start of injection
- Duration of injection
This management system is connected to the transmission allowing the engine and transmission to respond simultaneously.
Cold-weather and high-altitude compensation are also precisely controlled for quality starts regardless of weather and proper power levels at high elevations.
Injectors deliver the same fuel pressure level to cylinders from the high-pressure common rail:
- Magnetic valve provides fast and precisely metered fuel injection.
- Six-hole nozzles give optimum spray patterns and fine fuel atomization.
Performance-matched fuel consumption delivers reduced fuel costs per acre.