There
are three types of internal combustion engines used on fork
lift trucks although one of these is only used very rarely.
Diesel engines
 These
are very popular in counterbalanced fork lifts although their
physical size makes them an untenable proposition for other
machines the exception being rough terrain trucks and sideloaders.
They obviously use diesel fuel but can also
legally use so called 'red' diesel which is cheaper than normal
fuel. Note that trucks in use on the public highway cannot
legally use red diesel.
The benefits of diesel propelled fork lifts
are that the truck can be made very powerful with the ability
to climb quite steep gradients. Typically this type of truck
will also have a fast lift speed. It is not uncommon to see
this type of truck designed to traverse rough ground and fitted
with either pneumatic or supercushion tyres.
Some truck manufactures use their own manufactured
engines whilst others buy them in from companies such as Perkins
Engines and the like.
One problem with diesels not generally mentioned
is that they give off large amounts of sulphur. This means
that they should not be used in confined spaces and if they
have to be, a full risk assessment should be carried out first.
In an effort to overcome this problem some trucks are fitted
with LP Gas engines but they are far from non toxic as explained
below.
Liquefied petroleum gas engines
Based on conventional internal combustion
engines these burn a lot cleaner than diesels although they
also should not be used in confined spaces as they give off
quantities of nitrous oxide which is of course, toxic. The
term 'clean' really refers to the visible exhaust gasses which
are infinitely cleaner than those from a diesel and as such
may sometimes be used where products would otherwise be contaminated
such as some types of food handling.
An LP Gas truck has a very simple carburetor
which is little more than a simple venturi through which air
is sucked allowing the gas to enter the engine prior to ignition.
The fuel burns more completely than a petrol engine and therefore
the exhaust emissions are much cleaner.
A few points about LPG systems that
should be noted:
If the accelerator is pressed hard down to
the floor during starting the engine will often fail to start!
This is because this action removes the vacuum from the inlet
manifold which then causes a safety valve to shut off the
gas supply! If this does happen, only press the accelerator
down a little.
LP Gas cylinders are heavy - particularly when full. If it
is too heavy, the person changing it should seek help. The
Manual handling regulations, (1992), apply in these cases.
The gas bottle should be mounted the correct way on the truck
with the arrow pointing down. If this is not done the bottle
may appear to be empty when there is in fact, some fuel left.
More important information about LP Gas, it's properties,
dangers and how to handle it safely can be found here>>
Petrol engines
Because of the contamination caused by this
type of motive power they tend not to be used in the United
Kingdom. I understand that they are used in some parts of
the USA and if anyone has information on this perhaps they
would contact me.
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