New Holland 667TA/EBF, Repair Manual

Page: 40 / 150

2-22
Issued 11-06 Bur 87519804 NA
CHAPTER 2 - 667TA ENGINE OVERHAUL
ENGINE REPAIR MANUAL
CAMSHAFT
BS06K025
Figure 2-18
BS06K026
Figure 2-19
The cam shaft is installed on 7 journals in the engine
block.
The front and rear bearing housings are equipped
with steel bearings plated with antifriction material
assembled by means of a foce-fit.
There are two cam lobes per cylinder.
A. Intake valve lobe.
B. Exhaust valve lobe.
The cam shaft is controlled directly by the crankshaft
by means of rear spur tooth gears.
EGR EXHAUST GAS RECIRCULATION
SYSTEM
The exhaust gases can be partially returned back
into the cylinders to lower the maximum combustion
temperature which is responsible for the production
of nitrogen oxides (NOX).
The exhaust gas recirculation system (EGR), lowers
the combustion temperature by decreasing the
concentration of oxygen in the combustion chamber.
Creating an effective system to control the emission
of NOx.
The inter nal EGR system exhaust cam design
permits some of the exhaust gases to be returned
back into the engine cylinders. This type of EGR,
internal EGR is not provided with any electronically
controlled element. The system is always on. Its
configuration doesn’t need any additional elements
such as control valves, lines or heat exchangers.
The exhaust cam, beside the main lobe, has an
additional lobe (C) compared to a cam without EGR.
During the intake stroke of a cylinder this lobe
permits a brief opening of the exhaust valve. This
way recirculation is generated in the cylinder in the
cylinder during the intake stroke due to the greater
pressure of the exhaust gases compared to the
intake gases.
A. INTAKE VALVE LOBE B. EXHAUST VALVE LOBE C. EGR LOBE
B
A
C