IC engine - clean exhaust depends on a catalytic converter. The stringent requirement for forklift trucks minimizes the release of harmful exhaust to environment. The toxic gases "carbonmonoxide and soot" are cleaned via a catalytic converter.

Two basic converter types used are:

• Dry exhaust (catalytic converter) 

- used with gasoline IC engines  - The exhaust is burned in an afterburner. After reaching a specified temperature the harmful gases are further reduced through an oxidation process. 

• Wet exhaust (catalytic converter) 

- used in Diesel applications - The exhaust gas is forced through a water bath which filters soot and reduces the unpleasant aroma expended by these engines. Afterwards the exhaust gas is forced into an afterburner for further purification.