JCB EcoMAX Engine Installation Manual
Page 18 of 64 320/A9164-1 © JCB Power Systems Ltd.
The NOx sensor must not be removed from the stub pipe. Welding this stub pipe is also not
approved. The JCB flange, which is supplied loose, may be welded and then bolted, with the
supplied gasket, to the stub pipe.
6.3.1 Exhaust Mounting
The exhaust must be supported so that the stresses generated in the exhaust due to thermal
expansion, engine vibration, (cab vibration if the muffler is mounted to the cab) and vibration
induced through operation of the machine doesn’t exceed the capability of the materials
used.
Vibration from the exhaust can be a source of noise in the cab. This is a particular issue with
A-pillar mounted systems so you must be very careful with these types of mounting systems.
Use appropriate anti-vibration mounts where you have to attach the exhaust to bodywork or
chassis.
Consideration to the exhaust loading on the aftertreatment outlet stub pipe should be
undertaken during the design phase so that the weight of a stub pipe does not exceed 5Kg
and 300mm in length. If a longer exhaust system is required it must be supported within
500mm of the mounting flange and be fitted with a flexible element before the support.
6.3.2 Flexible Elements
A flexible elements must be fitted downstream of the SCR can interface in a position so that
that they will compress longitudinally to accommodate thermal expansion. Equally, the OEM
must install a flexible element to allow for relative movement between the
engine/aftertreatment arrangement and the fixed machine. Production tolerance should also
be considered and the installer must ensure the flexible element isn’t pre-loaded during
assembly.
The expansion coefficient for steel is approximately 1 mm per metre of pipe per 100ºC
temperature rise. So, for example, a 2 metre pipe might be expected to expand by over 5
mm. You must allow for this by using a mounting system that allows for such expansion, or
include flexible bellows that allows for the compression without transmitting excessive forces
back into the manifold or support brackets.
6.3.3 Materials
Exhaust gas contains corrosive chemicals, as well as water vapour, so the materials
selected for the exhaust have a significant effect on the life of the system. Mild steel may be
used for commodity products downstream of the after-treatment catalyst, however austenitic
steel is recommended.
N NOTE: Engine meeting Stage 3b and newer legislation produce significantly less
soot than previous engines and therefore exhaust systems used on previous
emissions Stage engines may corrode more quickly. This is because soot acts as a
corrosion barrier.
6.3.4 Pipe Sizes and Bends
The exhaust pipe must be at least a nominal 60 mm internal diameter, including pipework
inside the silencer.
Avoid sharp bends as they increase restriction. Make all bends around as large a radius as
possible and avoid mitred joint type bends if possible.
Restriction is inversely proportional to the 5th power of pipe diameter so, if you need a
complex routing with many bends for package reasons, a small increase in pipe diameter
can help to compensate for the restriction caused by the bends.
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